text: /*
   * ring buffer based function tracer
   *
   * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
   * Copyright (C) 2008 Ingo Molnar <mingo@redhat.com>
   *
   * Originally taken from the RT patch by:
   *    Arnaldo Carvalho de Melo <acme@redhat.com>
   *
   * Based on code from the latency_tracer, that is:
   *  Copyright (C) 2004-2006 Ingo Molnar
   *  Copyright (C) 2004 William Lee Irwin III
   */
  #include <linux/ring_buffer.h>
  #include <generated/utsrelease.h>
  #include <linux/stacktrace.h>
  #include <linux/writeback.h>
  #include <linux/kallsyms.h>
  #include <linux/seq_file.h>
  #include <linux/smp_lock.h>
  #include <linux/notifier.h>
  #include <linux/irqflags.h>
  #include <linux/debugfs.h>
  #include <linux/pagemap.h>
  #include <linux/hardirq.h>
  #include <linux/linkage.h>
  #include <linux/uaccess.h>
  #include <linux/kprobes.h>
  #include <linux/ftrace.h>
  #include <linux/module.h>
  #include <linux/percpu.h>
  #include <linux/splice.h>
  #include <linux/kdebug.h>
  #include <linux/string.h>
  #include <linux/rwsem.h>
  #include <linux/slab.h>
  #include <linux/ctype.h>
  #include <linux/init.h>
  #include <linux/poll.h>
  #include <linux/fs.h>
  
  #include "trace.h"
  #include "trace_output.h"
  
  #define TRACE_BUFFER_FLAGS	(RB_FL_OVERWRITE)
  
  /*
   * On boot up, the ring buffer is set to the minimum size, so that
   * we do not waste memory on systems that are not using tracing.
   */
  int ring_buffer_expanded;
  
  /*
   * We need to change this state when a selftest is running.
   * A selftest will lurk into the ring-buffer to count the
   * entries inserted during the selftest although some concurrent
   * insertions into the ring-buffer such as trace_printk could occurred
   * at the same time, giving false positive or negative results.
   */
  static bool __read_mostly tracing_selftest_running;
  
  /*
   * If a tracer is running, we do not want to run SELFTEST.
   */
  bool __read_mostly tracing_selftest_disabled;
  
  /* For tracers that don't implement custom flags */
  static struct tracer_opt dummy_tracer_opt[] = {
  	{ }
  };
  
  static struct tracer_flags dummy_tracer_flags = {
  	.val = 0,
  	.opts = dummy_tracer_opt
  };
  
  static int dummy_set_flag(u32 old_flags, u32 bit, int set)
  {
  	return 0;
  }
  
  /*
   * Kill all tracing for good (never come back).
   * It is initialized to 1 but will turn to zero if the initialization
   * of the tracer is successful. But that is the only place that sets
   * this back to zero.
   */
  static int tracing_disabled = 1;
  
  DEFINE_PER_CPU(int, ftrace_cpu_disabled);
  
  static inline void ftrace_disable_cpu(void)
  {
  	preempt_disable();
  	__this_cpu_inc(ftrace_cpu_disabled);
  }
  
  static inline void ftrace_enable_cpu(void)
  {
  	__this_cpu_dec(ftrace_cpu_disabled);
  	preempt_enable();
  }
  
  static cpumask_var_t __read_mostly	tracing_buffer_mask;
  
  #define for_each_tracing_cpu(cpu)	\
  	for_each_cpu(cpu, tracing_buffer_mask)
  
  /*
   * ftrace_dump_on_oops - variable to dump ftrace buffer on oops
   *
   * If there is an oops (or kernel panic) and the ftrace_dump_on_oops
   * is set, then ftrace_dump is called. This will output the contents
   * of the ftrace buffers to the console.  This is very useful for
   * capturing traces that lead to crashes and outputing it to a
   * serial console.
   *
   * It is default off, but you can enable it with either specifying
   * "ftrace_dump_on_oops" in the kernel command line, or setting
   * /proc/sys/kernel/ftrace_dump_on_oops to true.
   */
  int ftrace_dump_on_oops;
  
  static int tracing_set_tracer(const char *buf);
  
  #define MAX_TRACER_SIZE		100
  static char bootup_tracer_buf[MAX_TRACER_SIZE] __initdata;
  static char *default_bootup_tracer;
  
  static int __init set_cmdline_ftrace(char *str)
  {
  	strncpy(bootup_tracer_buf, str, MAX_TRACER_SIZE);
  	default_bootup_tracer = bootup_tracer_buf;
  	/* We are using ftrace early, expand it */
  	ring_buffer_expanded = 1;
  	return 1;
  }
  __setup("ftrace=", set_cmdline_ftrace);
  
  static int __init set_ftrace_dump_on_oops(char *str)
  {
  	ftrace_dump_on_oops = 1;
  	return 1;
  }
  __setup("ftrace_dump_on_oops", set_ftrace_dump_on_oops);
  
  unsigned long long ns2usecs(cycle_t nsec)
  {
  	nsec += 500;
  	do_div(nsec, 1000);
  	return nsec;
  }
  
  /*
   * The global_trace is the descriptor that holds the tracing
   * buffers for the live tracing. For each CPU, it contains
   * a link list of pages that will store trace entries. The
   * page descriptor of the pages in the memory is used to hold
   * the link list by linking the lru item in the page descriptor
   * to each of the pages in the buffer per CPU.
   *
   * For each active CPU there is a data field that holds the
   * pages for the buffer for that CPU. Each CPU has the same number
   * of pages allocated for its buffer.
   */
  static struct trace_array	global_trace;
  
  static DEFINE_PER_CPU(struct trace_array_cpu, global_trace_cpu);
  
  int filter_current_check_discard(struct ring_buffer *buffer,
  				 struct ftrace_event_call *call, void *rec,
  				 struct ring_buffer_event *event)
  {
  	return filter_check_discard(call, rec, buffer, event);
  }
  EXPORT_SYMBOL_GPL(filter_current_check_discard);
  
  cycle_t ftrace_now(int cpu)
  {
  	u64 ts;
  
  	/* Early boot up does not have a buffer yet */
  	if (!global_trace.buffer)
  		return trace_clock_local();
  
  	ts = ring_buffer_time_stamp(global_trace.buffer, cpu);
  	ring_buffer_normalize_time_stamp(global_trace.buffer, cpu, &ts);
  
  	return ts;
  }
  
  /*
   * The max_tr is used to snapshot the global_trace when a maximum
   * latency is reached. Some tracers will use this to store a maximum
   * trace while it continues examining live traces.
   *
   * The buffers for the max_tr are set up the same as the global_trace.
   * When a snapshot is taken, the link list of the max_tr is swapped
   * with the link list of the global_trace and the buffers are reset for
   * the global_trace so the tracing can continue.
   */
  static struct trace_array	max_tr;
  
  static DEFINE_PER_CPU(struct trace_array_cpu, max_tr_data);
  
  /* tracer_enabled is used to toggle activation of a tracer */
  static int			tracer_enabled = 1;
  
  /**
   * tracing_is_enabled - return tracer_enabled status
   *
   * This function is used by other tracers to know the status
   * of the tracer_enabled flag.  Tracers may use this function
   * to know if it should enable their features when starting
   * up. See irqsoff tracer for an example (start_irqsoff_tracer).
   */
  int tracing_is_enabled(void)
  {
  	return tracer_enabled;
  }
  
  /*
   * trace_buf_size is the size in bytes that is allocated
   * for a buffer. Note, the number of bytes is always rounded
   * to page size.
   *
   * This number is purposely set to a low number of 16384.
   * If the dump on oops happens, it will be much appreciated
   * to not have to wait for all that output. Anyway this can be
   * boot time and run time configurable.
   */
  #define TRACE_BUF_SIZE_DEFAULT	1441792UL /* 16384 * 88 (sizeof(entry)) */
  
  static unsigned long		trace_buf_size = TRACE_BUF_SIZE_DEFAULT;
  
  /* trace_types holds a link list of available tracers. */
  static struct tracer		*trace_types __read_mostly;
  
  /* current_trace points to the tracer that is currently active */
  static struct tracer		*current_trace __read_mostly;
  
  /*
   * trace_types_lock is used to protect the trace_types list.
   */
  static DEFINE_MUTEX(trace_types_lock);
  
  /*
   * serialize the access of the ring buffer
   *
   * ring buffer serializes readers, but it is low level protection.
   * The validity of the events (which returns by ring_buffer_peek() ..etc)
   * are not protected by ring buffer.
   *
   * The content of events may become garbage if we allow other process consumes
   * these events concurrently:
   *   A) the page of the consumed events may become a normal page
   *      (not reader page) in ring buffer, and this page will be rewrited
   *      by events producer.
   *   B) The page of the consumed events may become a page for splice_read,
   *      and this page will be returned to system.
   *
   * These primitives allow multi process access to different cpu ring buffer
   * concurrently.
   *
   * These primitives don't distinguish read-only and read-consume access.
   * Multi read-only access are also serialized.
   */
  
  #ifdef CONFIG_SMP
  static DECLARE_RWSEM(all_cpu_access_lock);
  static DEFINE_PER_CPU(struct mutex, cpu_access_lock);
  
  static inline void trace_access_lock(int cpu)
  {
  	if (cpu == TRACE_PIPE_ALL_CPU) {
  		/* gain it for accessing the whole ring buffer. */
  		down_write(&all_cpu_access_lock);
  	} else {
  		/* gain it for accessing a cpu ring buffer. */
  
  		/* Firstly block other trace_access_lock(TRACE_PIPE_ALL_CPU). */
  		down_read(&all_cpu_access_lock);
  
  		/* Secondly block other access to this @cpu ring buffer. */
  		mutex_lock(&per_cpu(cpu_access_lock, cpu));
  	}
  }
  
  static inline void trace_access_unlock(int cpu)
  {
  	if (cpu == TRACE_PIPE_ALL_CPU) {
  		up_write(&all_cpu_access_lock);
  	} else {
  		mutex_unlock(&per_cpu(cpu_access_lock, cpu));
  		up_read(&all_cpu_access_lock);
  	}
  }
  
  static inline void trace_access_lock_init(void)
  {
  	int cpu;
  
  	for_each_possible_cpu(cpu)
  		mutex_init(&per_cpu(cpu_access_lock, cpu));
  }
  
  #else
  
  static DEFINE_MUTEX(access_lock);
  
  static inline void trace_access_lock(int cpu)
  {
  	(void)cpu;
  	mutex_lock(&access_lock);
  }
  
  static inline void trace_access_unlock(int cpu)
  {
  	(void)cpu;
  	mutex_unlock(&access_lock);
  }
  
  static inline void trace_access_lock_init(void)
  {
  }
  
  #endif
  
  /* trace_wait is a waitqueue for tasks blocked on trace_poll */
  static DECLARE_WAIT_QUEUE_HEAD(trace_wait);
  
  /* trace_flags holds trace_options default values */
  unsigned long trace_flags = TRACE_ITER_PRINT_PARENT | TRACE_ITER_PRINTK |
  	TRACE_ITER_ANNOTATE | TRACE_ITER_CONTEXT_INFO | TRACE_ITER_SLEEP_TIME |
  	TRACE_ITER_GRAPH_TIME;
  
  static int trace_stop_count;
  static DEFINE_SPINLOCK(tracing_start_lock);
  
  /**
   * trace_wake_up - wake up tasks waiting for trace input
   *
   * Simply wakes up any task that is blocked on the trace_wait
   * queue. These is used with trace_poll for tasks polling the trace.
   */
  void trace_wake_up(void)
  {
  	int cpu;
  
  	if (trace_flags & TRACE_ITER_BLOCK)
  		return;
  	/*
  	 * The runqueue_is_locked() can fail, but this is the best we
  	 * have for now:
  	 */
  	cpu = get_cpu();
  	if (!runqueue_is_locked(cpu))
  		wake_up(&trace_wait);
  	put_cpu();
  }
  
  static int __init set_buf_size(char *str)
  {
  	unsigned long buf_size;
  
  	if (!str)
  		return 0;
  	buf_size = memparse(str, &str);
  	/* nr_entries can not be zero */
  	if (buf_size == 0)
  		return 0;
  	trace_buf_size = buf_size;
  	return 1;
  }
  __setup("trace_buf_size=", set_buf_size);
  
  static int __init set_tracing_thresh(char *str)
  {
  	unsigned long threshhold;
  	int ret;
  
  	if (!str)
  		return 0;
  	ret = strict_strtoul(str, 0, &threshhold);
  	if (ret < 0)
  		return 0;
  	tracing_thresh = threshhold * 1000;
  	return 1;
  }
  __setup("tracing_thresh=", set_tracing_thresh);
  
  unsigned long nsecs_to_usecs(unsigned long nsecs)
  {
  	return nsecs / 1000;
  }
  
  /* These must match the bit postions in trace_iterator_flags */
  static const char *trace_options[] = {
  	"print-parent",
  	"sym-offset",
  	"sym-addr",
  	"verbose",
  	"raw",
  	"hex",
  	"bin",
  	"block",
  	"stacktrace",
  	"trace_printk",
  	"ftrace_preempt",
  	"branch",
  	"annotate",
  	"userstacktrace",
  	"sym-userobj",
  	"printk-msg-only",
  	"context-info",
  	"latency-format",
  	"sleep-time",
  	"graph-time",
  	NULL
  };
  
  static struct {
  	u64 (*func)(void);
  	const char *name;
  } trace_clocks[] = {
  	{ trace_clock_local,	"local" },
  	{ trace_clock_global,	"global" },
  };
  
  int trace_clock_id;
  
  /*
   * trace_parser_get_init - gets the buffer for trace parser
   */
  int trace_parser_get_init(struct trace_parser *parser, int size)
  {
  	memset(parser, 0, sizeof(*parser));
  
  	parser->buffer = kmalloc(size, GFP_KERNEL);
  	if (!parser->buffer)
  		return 1;
  
  	parser->size = size;
  	return 0;
  }
  
  /*
   * trace_parser_put - frees the buffer for trace parser
   */
  void trace_parser_put(struct trace_parser *parser)
  {
  	kfree(parser->buffer);
  }
  
  /*
   * trace_get_user - reads the user input string separated by  space
   * (matched by isspace(ch))
   *
   * For each string found the 'struct trace_parser' is updated,
   * and the function returns.
   *
   * Returns number of bytes read.
   *
   * See kernel/trace/trace.h for 'struct trace_parser' details.
   */
  int trace_get_user(struct trace_parser *parser, const char __user *ubuf,
  	size_t cnt, loff_t *ppos)
  {
  	char ch;
  	size_t read = 0;
  	ssize_t ret;
  
  	if (!*ppos)
  		trace_parser_clear(parser);
  
  	ret = get_user(ch, ubuf++);
  	if (ret)
  		goto out;
  
  	read++;
  	cnt--;
  
  	/*
  	 * The parser is not finished with the last write,
  	 * continue reading the user input without skipping spaces.
  	 */
  	if (!parser->cont) {
  		/* skip white space */
  		while (cnt && isspace(ch)) {
  			ret = get_user(ch, ubuf++);
  			if (ret)
  				goto out;
  			read++;
  			cnt--;
  		}
  
  		/* only spaces were written */
  		if (isspace(ch)) {
  			*ppos += read;
  			ret = read;
  			goto out;
  		}
  
  		parser->idx = 0;
  	}
  
  	/* read the non-space input */
  	while (cnt && !isspace(ch)) {
  		if (parser->idx < parser->size - 1)
  			parser->buffer[parser->idx++] = ch;
  		else {
  			ret = -EINVAL;
  			goto out;
  		}
  		ret = get_user(ch, ubuf++);
  		if (ret)
  			goto out;
  		read++;
  		cnt--;
  	}
  
  	/* We either got finished input or we have to wait for another call. */
  	if (isspace(ch)) {
  		parser->buffer[parser->idx] = 0;
  		parser->cont = false;
  	} else {
  		parser->cont = true;
  		parser->buffer[parser->idx++] = ch;
  	}
  
  	*ppos += read;
  	ret = read;
  
  out:
  	return ret;
  }
  
  ssize_t trace_seq_to_user(struct trace_seq *s, char __user *ubuf, size_t cnt)
  {
  	int len;
  	int ret;
  
  	if (!cnt)
  		return 0;
  
  	if (s->len <= s->readpos)
  		return -EBUSY;
  
  	len = s->len - s->readpos;
  	if (cnt > len)
  		cnt = len;
  	ret = copy_to_user(ubuf, s->buffer + s->readpos, cnt);
  	if (ret == cnt)
  		return -EFAULT;
  
  	cnt -= ret;
  
  	s->readpos += cnt;
  	return cnt;
  }
  
  static ssize_t trace_seq_to_buffer(struct trace_seq *s, void *buf, size_t cnt)
  {
  	int len;
  	void *ret;
  
  	if (s->len <= s->readpos)
  		return -EBUSY;
  
  	len = s->len - s->readpos;
  	if (cnt > len)
  		cnt = len;
  	ret = memcpy(buf, s->buffer + s->readpos, cnt);
  	if (!ret)
  		return -EFAULT;
  
  	s->readpos += cnt;
  	return cnt;
  }
  
  /*
   * ftrace_max_lock is used to protect the swapping of buffers
   * when taking a max snapshot. The buffers themselves are
   * protected by per_cpu spinlocks. But the action of the swap
   * needs its own lock.
   *
   * This is defined as a arch_spinlock_t in order to help
   * with performance when lockdep debugging is enabled.
   *
   * It is also used in other places outside the update_max_tr
   * so it needs to be defined outside of the
   * CONFIG_TRACER_MAX_TRACE.
   */
  static arch_spinlock_t ftrace_max_lock =
  	(arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
  
  unsigned long __read_mostly	tracing_thresh;
  
  #ifdef CONFIG_TRACER_MAX_TRACE
  unsigned long __read_mostly	tracing_max_latency;
  
  /*
   * Copy the new maximum trace into the separate maximum-trace
   * structure. (this way the maximum trace is permanently saved,
   * for later retrieval via /sys/kernel/debug/tracing/latency_trace)
   */
  static void
  __update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu)
  {
  	struct trace_array_cpu *data = tr->data[cpu];
  	struct trace_array_cpu *max_data;
  
  	max_tr.cpu = cpu;
  	max_tr.time_start = data->preempt_timestamp;
  
  	max_data = max_tr.data[cpu];
  	max_data->saved_latency = tracing_max_latency;
  	max_data->critical_start = data->critical_start;
  	max_data->critical_end = data->critical_end;
  
  	memcpy(max_data->comm, tsk->comm, TASK_COMM_LEN);
  	max_data->pid = tsk->pid;
  	max_data->uid = task_uid(tsk);
  	max_data->nice = tsk->static_prio - 20 - MAX_RT_PRIO;
  	max_data->policy = tsk->policy;
  	max_data->rt_priority = tsk->rt_priority;
  
  	/* record this tasks comm */
  	tracing_record_cmdline(tsk);
  }
  
  /**
   * update_max_tr - snapshot all trace buffers from global_trace to max_tr
   * @tr: tracer
   * @tsk: the task with the latency
   * @cpu: The cpu that initiated the trace.
   *
   * Flip the buffers between the @tr and the max_tr and record information
   * about which task was the cause of this latency.
   */
  void
  update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu)
  {
  	struct ring_buffer *buf = tr->buffer;
  
  	if (trace_stop_count)
  		return;
  
  	WARN_ON_ONCE(!irqs_disabled());
  	arch_spin_lock(&ftrace_max_lock);
  
  	tr->buffer = max_tr.buffer;
  	max_tr.buffer = buf;
  
  	__update_max_tr(tr, tsk, cpu);
  	arch_spin_unlock(&ftrace_max_lock);
  }
  
  /**
   * update_max_tr_single - only copy one trace over, and reset the rest
   * @tr - tracer
   * @tsk - task with the latency
   * @cpu - the cpu of the buffer to copy.
   *
   * Flip the trace of a single CPU buffer between the @tr and the max_tr.
   */
  void
  update_max_tr_single(struct trace_array *tr, struct task_struct *tsk, int cpu)
  {
  	int ret;
  
  	if (trace_stop_count)
  		return;
  
  	WARN_ON_ONCE(!irqs_disabled());
  	arch_spin_lock(&ftrace_max_lock);
  
  	ftrace_disable_cpu();
  
  	ret = ring_buffer_swap_cpu(max_tr.buffer, tr->buffer, cpu);
  
  	if (ret == -EBUSY) {
  		/*
  		 * We failed to swap the buffer due to a commit taking
  		 * place on this CPU. We fail to record, but we reset
  		 * the max trace buffer (no one writes directly to it)
  		 * and flag that it failed.
  		 */
  		trace_array_printk(&max_tr, _THIS_IP_,
  			"Failed to swap buffers due to commit in progress\n");
  	}
  
  	ftrace_enable_cpu();
  
  	WARN_ON_ONCE(ret && ret != -EAGAIN && ret != -EBUSY);
  
  	__update_max_tr(tr, tsk, cpu);
  	arch_spin_unlock(&ftrace_max_lock);
  }
  #endif /* CONFIG_TRACER_MAX_TRACE */
  
  /**
   * register_tracer - register a tracer with the ftrace system.
   * @type - the plugin for the tracer
   *
   * Register a new plugin tracer.
   */
  int register_tracer(struct tracer *type)
  __releases(kernel_lock)
  __acquires(kernel_lock)
  {
  	struct tracer *t;
  	int ret = 0;
  
  	if (!type->name) {
  		pr_info("Tracer must have a name\n");
  		return -1;
  	}
  
  	if (strlen(type->name) > MAX_TRACER_SIZE) {
  		pr_info("Tracer has a name longer than %d\n", MAX_TRACER_SIZE);
  		return -1;
  	}
  
  	/*
  	 * When this gets called we hold the BKL which means that
  	 * preemption is disabled. Various trace selftests however
  	 * need to disable and enable preemption for successful tests.
  	 * So we drop the BKL here and grab it after the tests again.
  	 */
  	unlock_kernel();
  	mutex_lock(&trace_types_lock);
  
  	tracing_selftest_running = true;
  
  	for (t = trace_types; t; t = t->next) {
  		if (strcmp(type->name, t->name) == 0) {
  			/* already found */
  			pr_info("Tracer %s already registered\n",
  				type->name);
  			ret = -1;
  			goto out;
  		}
  	}
  
  	if (!type->set_flag)
  		type->set_flag = &dummy_set_flag;
  	if (!type->flags)
  		type->flags = &dummy_tracer_flags;
  	else
  		if (!type->flags->opts)
  			type->flags->opts = dummy_tracer_opt;
  	if (!type->wait_pipe)
  		type->wait_pipe = default_wait_pipe;
  
  
  #ifdef CONFIG_FTRACE_STARTUP_TEST
  	if (type->selftest && !tracing_selftest_disabled) {
  		struct tracer *saved_tracer = current_trace;
  		struct trace_array *tr = &global_trace;
  
  		/*
  		 * Run a selftest on this tracer.
  		 * Here we reset the trace buffer, and set the current
  		 * tracer to be this tracer. The tracer can then run some
  		 * internal tracing to verify that everything is in order.
  		 * If we fail, we do not register this tracer.
  		 */
  		tracing_reset_online_cpus(tr);
  
  		current_trace = type;
  		/* the test is responsible for initializing and enabling */
  		pr_info("Testing tracer %s: ", type->name);
  		ret = type->selftest(type, tr);
  		/* the test is responsible for resetting too */
  		current_trace = saved_tracer;
  		if (ret) {
  			printk(KERN_CONT "FAILED!\n");
  			goto out;
  		}
  		/* Only reset on passing, to avoid touching corrupted buffers */
  		tracing_reset_online_cpus(tr);
  
  		printk(KERN_CONT "PASSED\n");
  	}
  #endif
  
  	type->next = trace_types;
  	trace_types = type;
  
   out:
  	tracing_selftest_running = false;
  	mutex_unlock(&trace_types_lock);
  
  	if (ret || !default_bootup_tracer)
  		goto out_unlock;
  
  	if (strncmp(default_bootup_tracer, type->name, MAX_TRACER_SIZE))
  		goto out_unlock;
  
  	printk(KERN_INFO "Starting tracer '%s'\n", type->name);
  	/* Do we want this tracer to start on bootup? */
  	tracing_set_tracer(type->name);
  	default_bootup_tracer = NULL;
  	/* disable other selftests, since this will break it. */
  	tracing_selftest_disabled = 1;
  #ifdef CONFIG_FTRACE_STARTUP_TEST
  	printk(KERN_INFO "Disabling FTRACE selftests due to running tracer '%s'\n",
  	       type->name);
  #endif
  
   out_unlock:
  	lock_kernel();
  	return ret;
  }
  
  void unregister_tracer(struct tracer *type)
  {
  	struct tracer **t;
  
  	mutex_lock(&trace_types_lock);
  	for (t = &trace_types; *t; t = &(*t)->next) {
  		if (*t == type)
  			goto found;
  	}
  	pr_info("Tracer %s not registered\n", type->name);
  	goto out;
  
   found:
  	*t = (*t)->next;
  
  	if (type == current_trace && tracer_enabled) {
  		tracer_enabled = 0;
  		tracing_stop();
  		if (current_trace->stop)
  			current_trace->stop(&global_trace);
  		current_trace = &nop_trace;
  	}
  out:
  	mutex_unlock(&trace_types_lock);
  }
  
  static void __tracing_reset(struct ring_buffer *buffer, int cpu)
  {
  	ftrace_disable_cpu();
  	ring_buffer_reset_cpu(buffer, cpu);
  	ftrace_enable_cpu();
  }
  
  void tracing_reset(struct trace_array *tr, int cpu)
  {
  	struct ring_buffer *buffer = tr->buffer;
  
  	ring_buffer_record_disable(buffer);
  
  	/* Make sure all commits have finished */
  	synchronize_sched();
  	__tracing_reset(buffer, cpu);
  
  	ring_buffer_record_enable(buffer);
  }
  
  void tracing_reset_online_cpus(struct trace_array *tr)
  {
  	struct ring_buffer *buffer = tr->buffer;
  	int cpu;
  
  	ring_buffer_record_disable(buffer);
  
  	/* Make sure all commits have finished */
  	synchronize_sched();
  
  	tr->time_start = ftrace_now(tr->cpu);
  
  	for_each_online_cpu(cpu)
  		__tracing_reset(buffer, cpu);
  
  	ring_buffer_record_enable(buffer);
  }
  
  void tracing_reset_current(int cpu)
  {
  	tracing_reset(&global_trace, cpu);
  }
  
  void tracing_reset_current_online_cpus(void)
  {
  	tracing_reset_online_cpus(&global_trace);
  }
  
  #define SAVED_CMDLINES 128
  #define NO_CMDLINE_MAP UINT_MAX
  static unsigned map_pid_to_cmdline[PID_MAX_DEFAULT+1];
  static unsigned map_cmdline_to_pid[SAVED_CMDLINES];
  static char saved_cmdlines[SAVED_CMDLINES][TASK_COMM_LEN];
  static int cmdline_idx;
  static arch_spinlock_t trace_cmdline_lock = __ARCH_SPIN_LOCK_UNLOCKED;
  
  /* temporary disable recording */
  static atomic_t trace_record_cmdline_disabled __read_mostly;
  
  static void trace_init_cmdlines(void)
  {
  	memset(&map_pid_to_cmdline, NO_CMDLINE_MAP, sizeof(map_pid_to_cmdline));
  	memset(&map_cmdline_to_pid, NO_CMDLINE_MAP, sizeof(map_cmdline_to_pid));
  	cmdline_idx = 0;
  }
  
  int is_tracing_stopped(void)
  {
  	return trace_stop_count;
  }
  
  /**
   * ftrace_off_permanent - disable all ftrace code permanently
   *
   * This should only be called when a serious anomally has
   * been detected.  This will turn off the function tracing,
   * ring buffers, and other tracing utilites. It takes no
   * locks and can be called from any context.
   */
  void ftrace_off_permanent(void)
  {
  	tracing_disabled = 1;
  	ftrace_stop();
  	tracing_off_permanent();
  }
  
  /**
   * tracing_start - quick start of the tracer
   *
   * If tracing is enabled but was stopped by tracing_stop,
   * this will start the tracer back up.
   */
  void tracing_start(void)
  {
  	struct ring_buffer *buffer;
  	unsigned long flags;
  
  	if (tracing_disabled)
  		return;
  
  	spin_lock_irqsave(&tracing_start_lock, flags);
  	if (--trace_stop_count) {
  		if (trace_stop_count < 0) {
  			/* Someone screwed up their debugging */
  			WARN_ON_ONCE(1);
  			trace_stop_count = 0;
  		}
  		goto out;
  	}
  
  	/* Prevent the buffers from switching */
  	arch_spin_lock(&ftrace_max_lock);
  
  	buffer = global_trace.buffer;
  	if (buffer)
  		ring_buffer_record_enable(buffer);
  
  	buffer = max_tr.buffer;
  	if (buffer)
  		ring_buffer_record_enable(buffer);
  
  	arch_spin_unlock(&ftrace_max_lock);
  
  	ftrace_start();
   out:
  	spin_unlock_irqrestore(&tracing_start_lock, flags);
  }
  
  /**
   * tracing_stop - quick stop of the tracer
   *
   * Light weight way to stop tracing. Use in conjunction with
   * tracing_start.
   */
  void tracing_stop(void)
  {
  	struct ring_buffer *buffer;
  	unsigned long flags;
  
  	ftrace_stop();
  	spin_lock_irqsave(&tracing_start_lock, flags);
  	if (trace_stop_count++)
  		goto out;
  
  	/* Prevent the buffers from switching */
  	arch_spin_lock(&ftrace_max_lock);
  
  	buffer = global_trace.buffer;
  	if (buffer)
  		ring_buffer_record_disable(buffer);
  
  	buffer = max_tr.buffer;
  	if (buffer)
  		ring_buffer_record_disable(buffer);
  
  	arch_spin_unlock(&ftrace_max_lock);
  
   out:
  	spin_unlock_irqrestore(&tracing_start_lock, flags);
  }
  
  void trace_stop_cmdline_recording(void);
  
  static void trace_save_cmdline(struct task_struct *tsk)
  {
  	unsigned pid, idx;
  
  	if (!tsk->pid || unlikely(tsk->pid > PID_MAX_DEFAULT))
  		return;
  
  	/*
  	 * It's not the end of the world if we don't get
  	 * the lock, but we also don't want to spin
  	 * nor do we want to disable interrupts,
  	 * so if we miss here, then better luck next time.
  	 */
  	if (!arch_spin_trylock(&trace_cmdline_lock))
  		return;
  
  	idx = map_pid_to_cmdline[tsk->pid];
  	if (idx == NO_CMDLINE_MAP) {
  		idx = (cmdline_idx + 1) % SAVED_CMDLINES;
  
  		/*
  		 * Check whether the cmdline buffer at idx has a pid
  		 * mapped. We are going to overwrite that entry so we
  		 * need to clear the map_pid_to_cmdline. Otherwise we
  		 * would read the new comm for the old pid.
  		 */
  		pid = map_cmdline_to_pid[idx];
  		if (pid != NO_CMDLINE_MAP)
  			map_pid_to_cmdline[pid] = NO_CMDLINE_MAP;
  
  		map_cmdline_to_pid[idx] = tsk->pid;
  		map_pid_to_cmdline[tsk->pid] = idx;
  
  		cmdline_idx = idx;
  	}
  
  	memcpy(&saved_cmdlines[idx], tsk->comm, TASK_COMM_LEN);
  
  	arch_spin_unlock(&trace_cmdline_lock);
  }
  
  void trace_find_cmdline(int pid, char comm[])
  {
  	unsigned map;
  
  	if (!pid) {
  		strcpy(comm, "<idle>");
  		return;
  	}
  
  	if (WARN_ON_ONCE(pid < 0)) {
  		strcpy(comm, "<XXX>");
  		return;
  	}
  
  	if (pid > PID_MAX_DEFAULT) {
  		strcpy(comm, "<...>");
  		return;
  	}
  
  	preempt_disable();
  	arch_spin_lock(&trace_cmdline_lock);
  	map = map_pid_to_cmdline[pid];
  	if (map != NO_CMDLINE_MAP)
  		strcpy(comm, saved_cmdlines[map]);
  	else
  		strcpy(comm, "<...>");
  
  	arch_spin_unlock(&trace_cmdline_lock);
  	preempt_enable();
  }
  
  void tracing_record_cmdline(struct task_struct *tsk)
  {
  	if (atomic_read(&trace_record_cmdline_disabled) || !tracer_enabled ||
  	    !tracing_is_on())
  		return;
  
  	trace_save_cmdline(tsk);
  }
  
  void
  tracing_generic_entry_update(struct trace_entry *entry, unsigned long flags,
  			     int pc)
  {
  	struct task_struct *tsk = current;
  
  	entry->preempt_count		= pc & 0xff;
  	entry->pid			= (tsk) ? tsk->pid : 0;
  	entry->lock_depth		= (tsk) ? tsk->lock_depth : 0;
  	entry->flags =
  #ifdef CONFIG_TRACE_IRQFLAGS_SUPPORT
  		(irqs_disabled_flags(flags) ? TRACE_FLAG_IRQS_OFF : 0) |
  #else
  		TRACE_FLAG_IRQS_NOSUPPORT |
  #endif
  		((pc & HARDIRQ_MASK) ? TRACE_FLAG_HARDIRQ : 0) |
  		((pc & SOFTIRQ_MASK) ? TRACE_FLAG_SOFTIRQ : 0) |
  		(need_resched() ? TRACE_FLAG_NEED_RESCHED : 0);
  }
  EXPORT_SYMBOL_GPL(tracing_generic_entry_update);
  
  struct ring_buffer_event *
  trace_buffer_lock_reserve(struct ring_buffer *buffer,
  			  int type,
  			  unsigned long len,
  			  unsigned long flags, int pc)
  {
  	struct ring_buffer_event *event;
  
  	event = ring_buffer_lock_reserve(buffer, len);
  	if (event != NULL) {
  		struct trace_entry *ent = ring_buffer_event_data(event);
  
  		tracing_generic_entry_update(ent, flags, pc);
  		ent->type = type;
  	}
  
  	return event;
  }
  
  static inline void
  __trace_buffer_unlock_commit(struct ring_buffer *buffer,
  			     struct ring_buffer_event *event,
  			     unsigned long flags, int pc,
  			     int wake)
  {
  	ring_buffer_unlock_commit(buffer, event);
  
  	ftrace_trace_stack(buffer, flags, 6, pc);
  	ftrace_trace_userstack(buffer, flags, pc);
  
  	if (wake)
  		trace_wake_up();
  }
  
  void trace_buffer_unlock_commit(struct ring_buffer *buffer,
  				struct ring_buffer_event *event,
  				unsigned long flags, int pc)
  {
  	__trace_buffer_unlock_commit(buffer, event, flags, pc, 1);
  }
  
  struct ring_buffer_event *
  trace_current_buffer_lock_reserve(struct ring_buffer **current_rb,
  				  int type, unsigned long len,
  				  unsigned long flags, int pc)
  {
  	*current_rb = global_trace.buffer;
  	return trace_buffer_lock_reserve(*current_rb,
  					 type, len, flags, pc);
  }
  EXPORT_SYMBOL_GPL(trace_current_buffer_lock_reserve);
  
  void trace_current_buffer_unlock_commit(struct ring_buffer *buffer,
  					struct ring_buffer_event *event,
  					unsigned long flags, int pc)
  {
  	__trace_buffer_unlock_commit(buffer, event, flags, pc, 1);
  }
  EXPORT_SYMBOL_GPL(trace_current_buffer_unlock_commit);
  
  void trace_nowake_buffer_unlock_commit(struct ring_buffer *buffer,
  				       struct ring_buffer_event *event,
  				       unsigned long flags, int pc)
  {
  	__trace_buffer_unlock_commit(buffer, event, flags, pc, 0);
  }
  EXPORT_SYMBOL_GPL(trace_nowake_buffer_unlock_commit);
  
  void trace_current_buffer_discard_commit(struct ring_buffer *buffer,
  					 struct ring_buffer_event *event)
  {
  	ring_buffer_discard_commit(buffer, event);
  }
  EXPORT_SYMBOL_GPL(trace_current_buffer_discard_commit);
  
  void
  trace_function(struct trace_array *tr,
  	       unsigned long ip, unsigned long parent_ip, unsigned long flags,
  	       int pc)
  {
  	struct ftrace_event_call *call = &event_function;
  	struct ring_buffer *buffer = tr->buffer;
  	struct ring_buffer_event *event;
  	struct ftrace_entry *entry;
  
  	/* If we are reading the ring buffer, don't trace */
  	if (unlikely(__this_cpu_read(ftrace_cpu_disabled)))
  		return;
  
  	event = trace_buffer_lock_reserve(buffer, TRACE_FN, sizeof(*entry),
  					  flags, pc);
  	if (!event)
  		return;
  	entry	= ring_buffer_event_data(event);
  	entry->ip			= ip;
  	entry->parent_ip		= parent_ip;
  
  	if (!filter_check_discard(call, entry, buffer, event))
  		ring_buffer_unlock_commit(buffer, event);
  }
  
  void
  ftrace(struct trace_array *tr, struct trace_array_cpu *data,
         unsigned long ip, unsigned long parent_ip, unsigned long flags,
         int pc)
  {
  	if (likely(!atomic_read(&data->disabled)))
  		trace_function(tr, ip, parent_ip, flags, pc);
  }
  
  #ifdef CONFIG_STACKTRACE
  static void __ftrace_trace_stack(struct ring_buffer *buffer,
  				 unsigned long flags,
  				 int skip, int pc)
  {
  	struct ftrace_event_call *call = &event_kernel_stack;
  	struct ring_buffer_event *event;
  	struct stack_entry *entry;
  	struct stack_trace trace;
  
  	event = trace_buffer_lock_reserve(buffer, TRACE_STACK,
  					  sizeof(*entry), flags, pc);
  	if (!event)
  		return;
  	entry	= ring_buffer_event_data(event);
  	memset(&entry->caller, 0, sizeof(entry->caller));
  
  	trace.nr_entries	= 0;
  	trace.max_entries	= FTRACE_STACK_ENTRIES;
  	trace.skip		= skip;
  	trace.entries		= entry->caller;
  
  	save_stack_trace(&trace);
  	if (!filter_check_discard(call, entry, buffer, event))
  		ring_buffer_unlock_commit(buffer, event);
  }
  
  void ftrace_trace_stack(struct ring_buffer *buffer, unsigned long flags,
  			int skip, int pc)
  {
  	if (!(trace_flags & TRACE_ITER_STACKTRACE))
  		return;
  
  	__ftrace_trace_stack(buffer, flags, skip, pc);
  }
  
  void __trace_stack(struct trace_array *tr, unsigned long flags, int skip,
  		   int pc)
  {
  	__ftrace_trace_stack(tr->buffer, flags, skip, pc);
  }
  
  /**
   * trace_dump_stack - record a stack back trace in the trace buffer
   */
  void trace_dump_stack(void)
  {
  	unsigned long flags;
  
  	if (tracing_disabled || tracing_selftest_running)
  		return;
  
  	local_save_flags(flags);
  
  	/* skipping 3 traces, seems to get us at the caller of this function */
  	__ftrace_trace_stack(global_trace.buffer, flags, 3, preempt_count());
  }
  
  void
  ftrace_trace_userstack(struct ring_buffer *buffer, unsigned long flags, int pc)
  {
  	struct ftrace_event_call *call = &event_user_stack;
  	struct ring_buffer_event *event;
  	struct userstack_entry *entry;
  	struct stack_trace trace;
  
  	if (!(trace_flags & TRACE_ITER_USERSTACKTRACE))
  		return;
  
  	/*
  	 * NMIs can not handle page faults, even with fix ups.
  	 * The save user stack can (and often does) fault.
  	 */
  	if (unlikely(in_nmi()))
  		return;
  
  	event = trace_buffer_lock_reserve(buffer, TRACE_USER_STACK,
  					  sizeof(*entry), flags, pc);
  	if (!event)
  		return;
  	entry	= ring_buffer_event_data(event);
  
  	entry->tgid		= current->tgid;
  	memset(&entry->caller, 0, sizeof(entry->caller));
  
  	trace.nr_entries	= 0;
  	trace.max_entries	= FTRACE_STACK_ENTRIES;
  	trace.skip		= 0;
  	trace.entries		= entry->caller;
  
  	save_stack_trace_user(&trace);
  	if (!filter_check_discard(call, entry, buffer, event))
  		ring_buffer_unlock_commit(buffer, event);
  }
  
  #ifdef UNUSED
  static void __trace_userstack(struct trace_array *tr, unsigned long flags)
  {
  	ftrace_trace_userstack(tr, flags, preempt_count());
  }
  #endif /* UNUSED */
  
  #endif /* CONFIG_STACKTRACE */
  
  static void
  ftrace_trace_special(void *__tr,
  		     unsigned long arg1, unsigned long arg2, unsigned long arg3,
  		     int pc)
  {
  	struct ftrace_event_call *call = &event_special;
  	struct ring_buffer_event *event;
  	struct trace_array *tr = __tr;
  	struct ring_buffer *buffer = tr->buffer;
  	struct special_entry *entry;
  
  	event = trace_buffer_lock_reserve(buffer, TRACE_SPECIAL,
  					  sizeof(*entry), 0, pc);
  	if (!event)
  		return;
  	entry	= ring_buffer_event_data(event);
  	entry->arg1			= arg1;
  	entry->arg2			= arg2;
  	entry->arg3			= arg3;
  
  	if (!filter_check_discard(call, entry, buffer, event))
  		trace_buffer_unlock_commit(buffer, event, 0, pc);
  }
  
  void
  __trace_special(void *__tr, void *__data,
  		unsigned long arg1, unsigned long arg2, unsigned long arg3)
  {
  	ftrace_trace_special(__tr, arg1, arg2, arg3, preempt_count());
  }
  
  void
  ftrace_special(unsigned long arg1, unsigned long arg2, unsigned long arg3)
  {
  	struct trace_array *tr = &global_trace;
  	struct trace_array_cpu *data;
  	unsigned long flags;
  	int cpu;
  	int pc;
  
  	if (tracing_disabled)
  		return;
  
  	pc = preempt_count();
  	local_irq_save(flags);
  	cpu = raw_smp_processor_id();
  	data = tr->data[cpu];
  
  	if (likely(atomic_inc_return(&data->disabled) == 1))
  		ftrace_trace_special(tr, arg1, arg2, arg3, pc);
  
  	atomic_dec(&data->disabled);
  	local_irq_restore(flags);
  }
  
  /**
   * trace_vbprintk - write binary msg to tracing buffer
   *
   */
  int trace_vbprintk(unsigned long ip, const char *fmt, va_list args)
  {
  	static arch_spinlock_t trace_buf_lock =
  		(arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
  	static u32 trace_buf[TRACE_BUF_SIZE];
  
  	struct ftrace_event_call *call = &event_bprint;
  	struct ring_buffer_event *event;
  	struct ring_buffer *buffer;
  	struct trace_array *tr = &global_trace;
  	struct trace_array_cpu *data;
  	struct bprint_entry *entry;
  	unsigned long flags;
  	int disable;
  	int resched;
  	int cpu, len = 0, size, pc;
  
  	if (unlikely(tracing_selftest_running || tracing_disabled))
  		return 0;
  
  	/* Don't pollute graph traces with trace_vprintk internals */
  	pause_graph_tracing();
  
  	pc = preempt_count();
  	resched = ftrace_preempt_disable();
  	cpu = raw_smp_processor_id();
  	data = tr->data[cpu];
  
  	disable = atomic_inc_return(&data->disabled);
  	if (unlikely(disable != 1))
  		goto out;
  
  	/* Lockdep uses trace_printk for lock tracing */
  	local_irq_save(flags);
  	arch_spin_lock(&trace_buf_lock);
  	len = vbin_printf(trace_buf, TRACE_BUF_SIZE, fmt, args);
  
  	if (len > TRACE_BUF_SIZE || len < 0)
  		goto out_unlock;
  
  	size = sizeof(*entry) + sizeof(u32) * len;
  	buffer = tr->buffer;
  	event = trace_buffer_lock_reserve(buffer, TRACE_BPRINT, size,
  					  flags, pc);
  	if (!event)
  		goto out_unlock;
  	entry = ring_buffer_event_data(event);
  	entry->ip			= ip;
  	entry->fmt			= fmt;
  
  	memcpy(entry->buf, trace_buf, sizeof(u32) * len);
  	if (!filter_check_discard(call, entry, buffer, event)) {
  		ring_buffer_unlock_commit(buffer, event);
  		ftrace_trace_stack(buffer, flags, 6, pc);
  	}
  
  out_unlock:
  	arch_spin_unlock(&trace_buf_lock);
  	local_irq_restore(flags);
  
  out:
  	atomic_dec_return(&data->disabled);
  	ftrace_preempt_enable(resched);
  	unpause_graph_tracing();
  
  	return len;
  }
  EXPORT_SYMBOL_GPL(trace_vbprintk);
  
  int trace_array_printk(struct trace_array *tr,
  		       unsigned long ip, const char *fmt, ...)
  {
  	int ret;
  	va_list ap;
  
  	if (!(trace_flags & TRACE_ITER_PRINTK))
  		return 0;
  
  	va_start(ap, fmt);
  	ret = trace_array_vprintk(tr, ip, fmt, ap);
  	va_end(ap);
  	return ret;
  }
  
  int trace_array_vprintk(struct trace_array *tr,
  			unsigned long ip, const char *fmt, va_list args)
  {
  	static arch_spinlock_t trace_buf_lock = __ARCH_SPIN_LOCK_UNLOCKED;
  	static char trace_buf[TRACE_BUF_SIZE];
  
  	struct ftrace_event_call *call = &event_print;
  	struct ring_buffer_event *event;
  	struct ring_buffer *buffer;
  	struct trace_array_cpu *data;
  	int cpu, len = 0, size, pc;
  	struct print_entry *entry;
  	unsigned long irq_flags;
  	int disable;
  
  	if (tracing_disabled || tracing_selftest_running)
  		return 0;
  
  	pc = preempt_count();
  	preempt_disable_notrace();
  	cpu = raw_smp_processor_id();
  	data = tr->data[cpu];
  
  	disable = atomic_inc_return(&data->disabled);
  	if (unlikely(disable != 1))
  		goto out;
  
  	pause_graph_tracing();
  	raw_local_irq_save(irq_flags);
  	arch_spin_lock(&trace_buf_lock);
  	len = vsnprintf(trace_buf, TRACE_BUF_SIZE, fmt, args);
  
  	size = sizeof(*entry) + len + 1;
  	buffer = tr->buffer;
  	event = trace_buffer_lock_reserve(buffer, TRACE_PRINT, size,
  					  irq_flags, pc);
  	if (!event)
  		goto out_unlock;
  	entry = ring_buffer_event_data(event);
  	entry->ip = ip;
  
  	memcpy(&entry->buf, trace_buf, len);
  	entry->buf[len] = '\0';
  	if (!filter_check_discard(call, entry, buffer, event)) {
  		ring_buffer_unlock_commit(buffer, event);
  		ftrace_trace_stack(buffer, irq_flags, 6, pc);
  	}
  
   out_unlock:
  	arch_spin_unlock(&trace_buf_lock);
  	raw_local_irq_restore(irq_flags);
  	unpause_graph_tracing();
   out:
  	atomic_dec_return(&data->disabled);
  	preempt_enable_notrace();
  
  	return len;
  }
  
  int trace_vprintk(unsigned long ip, const char *fmt, va_list args)
  {
  	return trace_array_vprintk(&global_trace, ip, fmt, args);
  }
  EXPORT_SYMBOL_GPL(trace_vprintk);
  
  enum trace_file_type {
  	TRACE_FILE_LAT_FMT	= 1,
  	TRACE_FILE_ANNOTATE	= 2,
  };
  
  static void trace_iterator_increment(struct trace_iterator *iter)
  {
  	/* Don't allow ftrace to trace into the ring buffers */
  	ftrace_disable_cpu();
  
  	iter->idx++;
  	if (iter->buffer_iter[iter->cpu])
  		ring_buffer_read(iter->buffer_iter[iter->cpu], NULL);
  
  	ftrace_enable_cpu();
  }
  
  static struct trace_entry *
  peek_next_entry(struct trace_iterator *iter, int cpu, u64 *ts)
  {
  	struct ring_buffer_event *event;
  	struct ring_buffer_iter *buf_iter = iter->buffer_iter[cpu];
  
  	/* Don't allow ftrace to trace into the ring buffers */
  	ftrace_disable_cpu();
  
  	if (buf_iter)
  		event = ring_buffer_iter_peek(buf_iter, ts);
  	else
  		event = ring_buffer_peek(iter->tr->buffer, cpu, ts);
  
  	ftrace_enable_cpu();
  
  	return event ? ring_buffer_event_data(event) : NULL;
  }
  
  static struct trace_entry *
  __find_next_entry(struct trace_iterator *iter, int *ent_cpu, u64 *ent_ts)
  {
  	struct ring_buffer *buffer = iter->tr->buffer;
  	struct trace_entry *ent, *next = NULL;
  	int cpu_file = iter->cpu_file;
  	u64 next_ts = 0, ts;
  	int next_cpu = -1;
  	int cpu;
  
  	/*
  	 * If we are in a per_cpu trace file, don't bother by iterating over
  	 * all cpu and peek directly.
  	 */
  	if (cpu_file > TRACE_PIPE_ALL_CPU) {
  		if (ring_buffer_empty_cpu(buffer, cpu_file))
  			return NULL;
  		ent = peek_next_entry(iter, cpu_file, ent_ts);
  		if (ent_cpu)
  			*ent_cpu = cpu_file;
  
  		return ent;
  	}
  
  	for_each_tracing_cpu(cpu) {
  
  		if (ring_buffer_empty_cpu(buffer, cpu))
  			continue;
  
  		ent = peek_next_entry(iter, cpu, &ts);
  
  		/*
  		 * Pick the entry with the smallest timestamp:
  		 */
  		if (ent && (!next || ts < next_ts)) {
  			next = ent;
  			next_cpu = cpu;
  			next_ts = ts;
  		}
  	}
  
  	if (ent_cpu)
  		*ent_cpu = next_cpu;
  
  	if (ent_ts)
  		*ent_ts = next_ts;
  
  	return next;
  }
  
  /* Find the next real entry, without updating the iterator itself */
  struct trace_entry *trace_find_next_entry(struct trace_iterator *iter,
  					  int *ent_cpu, u64 *ent_ts)
  {
  	return __find_next_entry(iter, ent_cpu, ent_ts);
  }
  
  /* Find the next real entry, and increment the iterator to the next entry */
  static void *find_next_entry_inc(struct trace_iterator *iter)
  {
  	iter->ent = __find_next_entry(iter, &iter->cpu, &iter->ts);
  
  	if (iter->ent)
  		trace_iterator_increment(iter);
  
  	return iter->ent ? iter : NULL;
  }
  
  static void trace_consume(struct trace_iterator *iter)
  {
  	/* Don't allow ftrace to trace into the ring buffers */
  	ftrace_disable_cpu();
  	ring_buffer_consume(iter->tr->buffer, iter->cpu, &iter->ts);
  	ftrace_enable_cpu();
  }
  
  static void *s_next(struct seq_file *m, void *v, loff_t *pos)
  {
  	struct trace_iterator *iter = m->private;
  	int i = (int)*pos;
  	void *ent;
  
  	WARN_ON_ONCE(iter->leftover);
  
  	(*pos)++;
  
  	/* can't go backwards */
  	if (iter->idx > i)
  		return NULL;
  
  	if (iter->idx < 0)
  		ent = find_next_entry_inc(iter);
  	else
  		ent = iter;
  
  	while (ent && iter->idx < i)
  		ent = find_next_entry_inc(iter);
  
  	iter->pos = *pos;
  
  	return ent;
  }
  
  static void tracing_iter_reset(struct trace_iterator *iter, int cpu)
  {
  	struct trace_array *tr = iter->tr;
  	struct ring_buffer_event *event;
  	struct ring_buffer_iter *buf_iter;
  	unsigned long entries = 0;
  	u64 ts;
  
  	tr->data[cpu]->skipped_entries = 0;
  
  	if (!iter->buffer_iter[cpu])
  		return;
  
  	buf_iter = iter->buffer_iter[cpu];
  	ring_buffer_iter_reset(buf_iter);
  
  	/*
  	 * We could have the case with the max latency tracers
  	 * that a reset never took place on a cpu. This is evident
  	 * by the timestamp being before the start of the buffer.
  	 */
  	while ((event = ring_buffer_iter_peek(buf_iter, &ts))) {
  		if (ts >= iter->tr->time_start)
  			break;
  		entries++;
  		ring_buffer_read(buf_iter, NULL);
  	}
  
  	tr->data[cpu]->skipped_entries = entries;
  }
  
  /*
   * The current tracer is copied to avoid a global locking
   * all around.
   */
  static void *s_start(struct seq_file *m, loff_t *pos)
  {
  	struct trace_iterator *iter = m->private;
  	static struct tracer *old_tracer;
  	int cpu_file = iter->cpu_file;
  	void *p = NULL;
  	loff_t l = 0;
  	int cpu;
  
  	/* copy the tracer to avoid using a global lock all around */
  	mutex_lock(&trace_types_lock);
  	if (unlikely(old_tracer != current_trace && current_trace)) {
  		old_tracer = current_trace;
  		*iter->trace = *current_trace;
  	}
  	mutex_unlock(&trace_types_lock);
  
  	atomic_inc(&trace_record_cmdline_disabled);
  
  	if (*pos != iter->pos) {
  		iter->ent = NULL;
  		iter->cpu = 0;
  		iter->idx = -1;
  
  		ftrace_disable_cpu();
  
  		if (cpu_file == TRACE_PIPE_ALL_CPU) {
  			for_each_tracing_cpu(cpu)
  				tracing_iter_reset(iter, cpu);
  		} else
  			tracing_iter_reset(iter, cpu_file);
  
  		ftrace_enable_cpu();
  
  		iter->leftover = 0;
  		for (p = iter; p && l < *pos; p = s_next(m, p, &l))
  			;
  
  	} else {
  		/*
  		 * If we overflowed the seq_file before, then we want
  		 * to just reuse the trace_seq buffer again.
  		 */
  		if (iter->leftover)
  			p = iter;
  		else {
  			l = *pos - 1;
  			p = s_next(m, p, &l);
  		}
  	}
  
  	trace_event_read_lock();
  	trace_access_lock(cpu_file);
  	return p;
  }
  
  static void s_stop(struct seq_file *m, void *p)
  {
  	struct trace_iterator *iter = m->private;
  
  	atomic_dec(&trace_record_cmdline_disabled);
  	trace_access_unlock(iter->cpu_file);
  	trace_event_read_unlock();
  }
  
  static void print_lat_help_header(struct seq_file *m)
  {
  	seq_puts(m, "#                  _------=> CPU#            \n");
  	seq_puts(m, "#                 / _-----=> irqs-off        \n");
  	seq_puts(m, "#                | / _----=> need-resched    \n");
  	seq_puts(m, "#                || / _---=> hardirq/softirq \n");
  	seq_puts(m, "#                ||| / _--=> preempt-depth   \n");
  	seq_puts(m, "#                |||| /_--=> lock-depth       \n");
  	seq_puts(m, "#                |||||/     delay             \n");
  	seq_puts(m, "#  cmd     pid   |||||| time  |   caller      \n");
  	seq_puts(m, "#     \\   /      ||||||   \\   |   /           \n");
  }
  
  static void print_func_help_header(struct seq_file *m)
  {
  	seq_puts(m, "#           TASK-PID    CPU#    TIMESTAMP  FUNCTION\n");
  	seq_puts(m, "#              | |       |          |         |\n");
  }
  
  
  static void
  print_trace_header(struct seq_file *m, struct trace_iterator *iter)
  {
  	unsigned long sym_flags = (trace_flags & TRACE_ITER_SYM_MASK);
  	struct trace_array *tr = iter->tr;
  	struct trace_array_cpu *data = tr->data[tr->cpu];
  	struct tracer *type = current_trace;
  	unsigned long entries = 0;
  	unsigned long total = 0;
  	unsigned long count;
  	const char *name = "preemption";
  	int cpu;
  
  	if (type)
  		name = type->name;
  
  
  	for_each_tracing_cpu(cpu) {
  		count = ring_buffer_entries_cpu(tr->buffer, cpu);
  		/*
  		 * If this buffer has skipped entries, then we hold all
  		 * entries for the trace and we need to ignore the
  		 * ones before the time stamp.
  		 */
  		if (tr->data[cpu]->skipped_entries) {
  			count -= tr->data[cpu]->skipped_entries;
  			/* total is the same as the entries */
  			total += count;
  		} else
  			total += count +
  				ring_buffer_overrun_cpu(tr->buffer, cpu);
  		entries += count;
  	}
  
  	seq_printf(m, "# %s latency trace v1.1.5 on %s\n",
  		   name, UTS_RELEASE);
  	seq_puts(m, "# -----------------------------------"
  		 "---------------------------------\n");
  	seq_printf(m, "# latency: %lu us, #%lu/%lu, CPU#%d |"
  		   " (M:%s VP:%d, KP:%d, SP:%d HP:%d",
  		   nsecs_to_usecs(data->saved_latency),
  		   entries,
  		   total,
  		   tr->cpu,
  #if defined(CONFIG_PREEMPT_NONE)
  		   "server",
  #elif defined(CONFIG_PREEMPT_VOLUNTARY)
  		   "desktop",
  #elif defined(CONFIG_PREEMPT)
  		   "preempt",
  #else
  		   "unknown",
  #endif
  		   /* These are reserved for later use */
  		   0, 0, 0, 0);
  #ifdef CONFIG_SMP
  	seq_printf(m, " #P:%d)\n", num_online_cpus());
  #else
  	seq_puts(m, ")\n");
  #endif
  	seq_puts(m, "#    -----------------\n");
  	seq_printf(m, "#    | task: %.16s-%d "
  		   "(uid:%d nice:%ld policy:%ld rt_prio:%ld)\n",
  		   data->comm, data->pid, data->uid, data->nice,
  		   data->policy, data->rt_priority);
  	seq_puts(m, "#    -----------------\n");
  
  	if (data->critical_start) {
  		seq_puts(m, "#  => started at: ");
  		seq_print_ip_sym(&iter->seq, data->critical_start, sym_flags);
  		trace_print_seq(m, &iter->seq);
  		seq_puts(m, "\n#  => ended at:   ");
  		seq_print_ip_sym(&iter->seq, data->critical_end, sym_flags);
  		trace_print_seq(m, &iter->seq);
  		seq_puts(m, "\n#\n");
  	}
  
  	seq_puts(m, "#\n");
  }
  
  static void test_cpu_buff_start(struct trace_iterator *iter)
  {
  	struct trace_seq *s = &iter->seq;
  
  	if (!(trace_flags & TRACE_ITER_ANNOTATE))
  		return;
  
  	if (!(iter->iter_flags & TRACE_FILE_ANNOTATE))
  		return;
  
  	if (cpumask_test_cpu(iter->cpu, iter->started))
  		return;
  
  	if (iter->tr->data[iter->cpu]->skipped_entries)
  		return;
  
  	cpumask_set_cpu(iter->cpu, iter->started);
  
  	/* Don't print started cpu buffer for the first entry of the trace */
  	if (iter->idx > 1)
  		trace_seq_printf(s, "##### CPU %u buffer started ####\n",
  				iter->cpu);
  }
  
  static enum print_line_t print_trace_fmt(struct trace_iterator *iter)
  {
  	struct trace_seq *s = &iter->seq;
  	unsigned long sym_flags = (trace_flags & TRACE_ITER_SYM_MASK);
  	struct trace_entry *entry;
  	struct trace_event *event;
  
  	entry = iter->ent;
  
  	test_cpu_buff_start(iter);
  
  	event = ftrace_find_event(entry->type);
  
  	if (trace_flags & TRACE_ITER_CONTEXT_INFO) {
  		if (iter->iter_flags & TRACE_FILE_LAT_FMT) {
  			if (!trace_print_lat_context(iter))
  				goto partial;
  		} else {
  			if (!trace_print_context(iter))
  				goto partial;
  		}
  	}
  
  	if (event)
  		return event->trace(iter, sym_flags);
  
  	if (!trace_seq_printf(s, "Unknown type %d\n", entry->type))
  		goto partial;
  
  	return TRACE_TYPE_HANDLED;
  partial:
  	return TRACE_TYPE_PARTIAL_LINE;
  }
  
  static enum print_line_t print_raw_fmt(struct trace_iterator *iter)
  {
  	struct trace_seq *s = &iter->seq;
  	struct trace_entry *entry;
  	struct trace_event *event;
  
  	entry = iter->ent;
  
  	if (trace_flags & TRACE_ITER_CONTEXT_INFO) {
  		if (!trace_seq_printf(s, "%d %d %llu ",
  				      entry->pid, iter->cpu, iter->ts))
  			goto partial;
  	}
  
  	event = ftrace_find_event(entry->type);
  	if (event)
  		return event->raw(iter, 0);
  
  	if (!trace_seq_printf(s, "%d ?\n", entry->type))
  		goto partial;
  
  	return TRACE_TYPE_HANDLED;
  partial:
  	return TRACE_TYPE_PARTIAL_LINE;
  }
  
  static enum print_line_t print_hex_fmt(struct trace_iterator *iter)
  {
  	struct trace_seq *s = &iter->seq;
  	unsigned char newline = '\n';
  	struct trace_entry *entry;
  	struct trace_event *event;
  
  	entry = iter->ent;
  
  	if (trace_flags & TRACE_ITER_CONTEXT_INFO) {
  		SEQ_PUT_HEX_FIELD_RET(s, entry->pid);
  		SEQ_PUT_HEX_FIELD_RET(s, iter->cpu);
  		SEQ_PUT_HEX_FIELD_RET(s, iter->ts);
  	}
  
  	event = ftrace_find_event(entry->type);
  	if (event) {
  		enum print_line_t ret = event->hex(iter, 0);
  		if (ret != TRACE_TYPE_HANDLED)
  			return ret;
  	}
  
  	SEQ_PUT_FIELD_RET(s, newline);
  
  	return TRACE_TYPE_HANDLED;
  }
  
  static enum print_line_t print_bin_fmt(struct trace_iterator *iter)
  {
  	struct trace_seq *s = &iter->seq;
  	struct trace_entry *entry;
  	struct trace_event *event;
  
  	entry = iter->ent;
  
  	if (trace_flags & TRACE_ITER_CONTEXT_INFO) {
  		SEQ_PUT_FIELD_RET(s, entry->pid);
  		SEQ_PUT_FIELD_RET(s, iter->cpu);
  		SEQ_PUT_FIELD_RET(s, iter->ts);
  	}
  
  	event = ftrace_find_event(entry->type);
  	return event ? event->binary(iter, 0) : TRACE_TYPE_HANDLED;
  }
  
  static int trace_empty(struct trace_iterator *iter)
  {
  	int cpu;
  
  	/* If we are looking at one CPU buffer, only check that one */
  	if (iter->cpu_file != TRACE_PIPE_ALL_CPU) {
  		cpu = iter->cpu_file;
  		if (iter->buffer_iter[cpu]) {
  			if (!ring_buffer_iter_empty(iter->buffer_iter[cpu]))
  				return 0;
  		} else {
  			if (!ring_buffer_empty_cpu(iter->tr->buffer, cpu))
  				return 0;
  		}
  		return 1;
  	}
  
  	for_each_tracing_cpu(cpu) {
  		if (iter->buffer_iter[cpu]) {
  			if (!ring_buffer_iter_empty(iter->buffer_iter[cpu]))
  				return 0;
  		} else {
  			if (!ring_buffer_empty_cpu(iter->tr->buffer, cpu))
  				return 0;
  		}
  	}
  
  	return 1;
  }
  
  /*  Called with trace_event_read_lock() held. */
  static enum print_line_t print_trace_line(struct trace_iterator *iter)
  {
  	enum print_line_t ret;
  
  	if (iter->trace && iter->trace->print_line) {
  		ret = iter->trace->print_line(iter);
  		if (ret != TRACE_TYPE_UNHANDLED)
  			return ret;
  	}
  
  	if (iter->ent->type == TRACE_BPRINT &&
  			trace_flags & TRACE_ITER_PRINTK &&
  			trace_flags & TRACE_ITER_PRINTK_MSGONLY)
  		return trace_print_bprintk_msg_only(iter);
  
  	if (iter->ent->type == TRACE_PRINT &&
  			trace_flags & TRACE_ITER_PRINTK &&
  			trace_flags & TRACE_ITER_PRINTK_MSGONLY)
  		return trace_print_printk_msg_only(iter);
  
  	if (trace_flags & TRACE_ITER_BIN)
  		return print_bin_fmt(iter);
  
  	if (trace_flags & TRACE_ITER_HEX)
  		return print_hex_fmt(iter);
  
  	if (trace_flags & TRACE_ITER_RAW)
  		return print_raw_fmt(iter);
  
  	return print_trace_fmt(iter);
  }
  
  static int s_show(struct seq_file *m, void *v)
  {
  	struct trace_iterator *iter = v;
  	int ret;
  
  	if (iter->ent == NULL) {
  		if (iter->tr) {
  			seq_printf(m, "# tracer: %s\n", iter->trace->name);
  			seq_puts(m, "#\n");
  		}
  		if (iter->trace && iter->trace->print_header)
  			iter->trace->print_header(m);
  		else if (iter->iter_flags & TRACE_FILE_LAT_FMT) {
  			/* print nothing if the buffers are empty */
  			if (trace_empty(iter))
  				return 0;
  			print_trace_header(m, iter);
  			if (!(trace_flags & TRACE_ITER_VERBOSE))
  				print_lat_help_header(m);
  		} else {
  			if (!(trace_flags & TRACE_ITER_VERBOSE))
  				print_func_help_header(m);
  		}
  	} else if (iter->leftover) {
  		/*
  		 * If we filled the seq_file buffer earlier, we
  		 * want to just show it now.
  		 */
  		ret = trace_print_seq(m, &iter->seq);
  
  		/* ret should this time be zero, but you never know */
  		iter->leftover = ret;
  
  	} else {
  		print_trace_line(iter);
  		ret = trace_print_seq(m, &iter->seq);
  		/*
  		 * If we overflow the seq_file buffer, then it will
  		 * ask us for this data again at start up.
  		 * Use that instead.
  		 *  ret is 0 if seq_file write succeeded.
  		 *        -1 otherwise.
  		 */
  		iter->leftover = ret;
  	}
  
  	return 0;
  }
  
  static const struct seq_operations tracer_seq_ops = {
  	.start		= s_start,
  	.next		= s_next,
  	.stop		= s_stop,
  	.show		= s_show,
  };
  
  static struct trace_iterator *
  __tracing_open(struct inode *inode, struct file *file)
  {
  	long cpu_file = (long) inode->i_private;
  	void *fail_ret = ERR_PTR(-ENOMEM);
  	struct trace_iterator *iter;
  	struct seq_file *m;
  	int cpu, ret;
  
  	if (tracing_disabled)
  		return ERR_PTR(-ENODEV);
  
  	iter = kzalloc(sizeof(*iter), GFP_KERNEL);
  	if (!iter)
  		return ERR_PTR(-ENOMEM);
  
  	/*
  	 * We make a copy of the current tracer to avoid concurrent
  	 * changes on it while we are reading.
  	 */
  	mutex_lock(&trace_types_lock);
  	iter->trace = kzalloc(sizeof(*iter->trace), GFP_KERNEL);
  	if (!iter->trace)
  		goto fail;
  
  	if (current_trace)
  		*iter->trace = *current_trace;
  
  	if (!zalloc_cpumask_var(&iter->started, GFP_KERNEL))
  		goto fail;
  
  	if (current_trace && current_trace->print_max)
  		iter->tr = &max_tr;
  	else
  		iter->tr = &global_trace;
  	iter->pos = -1;
  	mutex_init(&iter->mutex);
  	iter->cpu_file = cpu_file;
  
  	/* Notify the tracer early; before we stop tracing. */
  	if (iter->trace && iter->trace->open)
  		iter->trace->open(iter);
  
  	/* Annotate start of buffers if we had overruns */
  	if (ring_buffer_overruns(iter->tr->buffer))
  		iter->iter_flags |= TRACE_FILE_ANNOTATE;
  
  	/* stop the trace while dumping */
  	tracing_stop();
  
  	if (iter->cpu_file == TRACE_PIPE_ALL_CPU) {
  		for_each_tracing_cpu(cpu) {
  
  			iter->buffer_iter[cpu] =
  				ring_buffer_read_start(iter->tr->buffer, cpu);
  			tracing_iter_reset(iter, cpu);
  		}
  	} else {
  		cpu = iter->cpu_file;
  		iter->buffer_iter[cpu] =
  				ring_buffer_read_start(iter->tr->buffer, cpu);
  		tracing_iter_reset(iter, cpu);
  	}
  
  	ret = seq_open(file, &tracer_seq_ops);
  	if (ret < 0) {
  		fail_ret = ERR_PTR(ret);
  		goto fail_buffer;
  	}
  
  	m = file->private_data;
  	m->private = iter;
  
  	mutex_unlock(&trace_types_lock);
  
  	return iter;
  
   fail_buffer:
  	for_each_tracing_cpu(cpu) {
  		if (iter->buffer_iter[cpu])
  			ring_buffer_read_finish(iter->buffer_iter[cpu]);
  	}
  	free_cpumask_var(iter->started);
  	tracing_start();
   fail:
  	mutex_unlock(&trace_types_lock);
  	kfree(iter->trace);
  	kfree(iter);
  
  	return fail_ret;
  }
  
  int tracing_open_generic(struct inode *inode, struct file *filp)
  {
  	if (tracing_disabled)
  		return -ENODEV;
  
  	filp->private_data = inode->i_private;
  	return 0;
  }
  
  static int tracing_release(struct inode *inode, struct file *file)
  {
  	struct seq_file *m = (struct seq_file *)file->private_data;
  	struct trace_iterator *iter;
  	int cpu;
  
  	if (!(file->f_mode & FMODE_READ))
  		return 0;
  
  	iter = m->private;
  
  	mutex_lock(&trace_types_lock);
  	for_each_tracing_cpu(cpu) {
  		if (iter->buffer_iter[cpu])
  			ring_buffer_read_finish(iter->buffer_iter[cpu]);
  	}
  
  	if (iter->trace && iter->trace->close)
  		iter->trace->close(iter);
  
  	/* reenable tracing if it was previously enabled */
  	tracing_start();
  	mutex_unlock(&trace_types_lock);
  
  	seq_release(inode, file);
  	mutex_destroy(&iter->mutex);
  	free_cpumask_var(iter->started);
  	kfree(iter->trace);
  	kfree(iter);
  	return 0;
  }
  
  static int tracing_open(struct inode *inode, struct file *file)
  {
  	struct trace_iterator *iter;
  	int ret = 0;
  
  	/* If this file was open for write, then erase contents */
  	if ((file->f_mode & FMODE_WRITE) &&
  	    (file->f_flags & O_TRUNC)) {
  		long cpu = (long) inode->i_private;
  
  		if (cpu == TRACE_PIPE_ALL_CPU)
  			tracing_reset_online_cpus(&global_trace);
  		else
  			tracing_reset(&global_trace, cpu);
  	}
  
  	if (file->f_mode & FMODE_READ) {
  		iter = __tracing_open(inode, file);
  		if (IS_ERR(iter))
  			ret = PTR_ERR(iter);
  		else if (trace_flags & TRACE_ITER_LATENCY_FMT)
  			iter->iter_flags |= TRACE_FILE_LAT_FMT;
  	}
  	return ret;
  }
  
  static void *
  t_next(struct seq_file *m, void *v, loff_t *pos)
  {
  	struct tracer *t = v;
  
  	(*pos)++;
  
  	if (t)
  		t = t->next;
  
  	return t;
  }
  
  static void *t_start(struct seq_file *m, loff_t *pos)
  {
  	struct tracer *t;
  	loff_t l = 0;
  
  	mutex_lock(&trace_types_lock);
  	for (t = trace_types; t && l < *pos; t = t_next(m, t, &l))
  		;
  
  	return t;
  }
  
  static void t_stop(struct seq_file *m, void *p)
  {
  	mutex_unlock(&trace_types_lock);
  }
  
  static int t_show(struct seq_file *m, void *v)
  {
  	struct tracer *t = v;
  
  	if (!t)
  		return 0;
  
  	seq_printf(m, "%s", t->name);
  	if (t->next)
  		seq_putc(m, ' ');
  	else
  		seq_putc(m, '\n');
  
  	return 0;
  }
  
  static const struct seq_operations show_traces_seq_ops = {
  	.start		= t_start,
  	.next		= t_next,
  	.stop		= t_stop,
  	.show		= t_show,
  };
  
  static int show_traces_open(struct inode *inode, struct file *file)
  {
  	if (tracing_disabled)
  		return -ENODEV;
  
  	return seq_open(file, &show_traces_seq_ops);
  }
  
  static ssize_t
  tracing_write_stub(struct file *filp, const char __user *ubuf,
  		   size_t count, loff_t *ppos)
  {
  	return count;
  }
  
  static const struct file_operations tracing_fops = {
  	.open		= tracing_open,
  	.read		= seq_read,
  	.write		= tracing_write_stub,
  	.llseek		= seq_lseek,
  	.release	= tracing_release,
  };
  
  static const struct file_operations show_traces_fops = {
  	.open		= show_traces_open,
  	.read		= seq_read,
  	.release	= seq_release,
  };
  
  /*
   * Only trace on a CPU if the bitmask is set:
   */
  static cpumask_var_t tracing_cpumask;
  
  /*
   * The tracer itself will not take this lock, but still we want
   * to provide a consistent cpumask to user-space:
   */
  static DEFINE_MUTEX(tracing_cpumask_update_lock);
  
  /*
   * Temporary storage for the character representation of the
   * CPU bitmask (and one more byte for the newline):
   */
  static char mask_str[NR_CPUS + 1];
  
  static ssize_t
  tracing_cpumask_read(struct file *filp, char __user *ubuf,
  		     size_t count, loff_t *ppos)
  {
  	int len;
  
  	mutex_lock(&tracing_cpumask_update_lock);
  
  	len = cpumask_scnprintf(mask_str, count, tracing_cpumask);
  	if (count - len < 2) {
  		count = -EINVAL;
  		goto out_err;
  	}
  	len += sprintf(mask_str + len, "\n");
  	count = simple_read_from_buffer(ubuf, count, ppos, mask_str, NR_CPUS+1);
  
  out_err:
  	mutex_unlock(&tracing_cpumask_update_lock);
  
  	return count;
  }
  
  static ssize_t
  tracing_cpumask_write(struct file *filp, const char __user *ubuf,
  		      size_t count, loff_t *ppos)
  {
  	int err, cpu;
  	cpumask_var_t tracing_cpumask_new;
  
  	if (!alloc_cpumask_var(&tracing_cpumask_new, GFP_KERNEL))
  		return -ENOMEM;
  
  	err = cpumask_parse_user(ubuf, count, tracing_cpumask_new);
  	if (err)
  		goto err_unlock;
  
  	mutex_lock(&tracing_cpumask_update_lock);
  
  	local_irq_disable();
  	arch_spin_lock(&ftrace_max_lock);
  	for_each_tracing_cpu(cpu) {
  		/*
  		 * Increase/decrease the disabled counter if we are
  		 * about to flip a bit in the cpumask:
  		 */
  		if (cpumask_test_cpu(cpu, tracing_cpumask) &&
  				!cpumask_test_cpu(cpu, tracing_cpumask_new)) {
  			atomic_inc(&global_trace.data[cpu]->disabled);
  		}
  		if (!cpumask_test_cpu(cpu, tracing_cpumask) &&
  				cpumask_test_cpu(cpu, tracing_cpumask_new)) {
  			atomic_dec(&global_trace.data[cpu]->disabled);
  		}
  	}
  	arch_spin_unlock(&ftrace_max_lock);
  	local_irq_enable();
  
  	cpumask_copy(tracing_cpumask, tracing_cpumask_new);
  
  	mutex_unlock(&tracing_cpumask_update_lock);
  	free_cpumask_var(tracing_cpumask_new);
  
  	return count;
  
  err_unlock:
  	free_cpumask_var(tracing_cpumask_new);
  
  	return err;
  }
  
  static const struct file_operations tracing_cpumask_fops = {
  	.open		= tracing_open_generic,
  	.read		= tracing_cpumask_read,
  	.write		= tracing_cpumask_write,
  };
  
  static int tracing_trace_options_show(struct seq_file *m, void *v)
  {
  	struct tracer_opt *trace_opts;
  	u32 tracer_flags;
  	int i;
  
  	mutex_lock(&trace_types_lock);
  	tracer_flags = current_trace->flags->val;
  	trace_opts = current_trace->flags->opts;
  
  	for (i = 0; trace_options[i]; i++) {
  		if (trace_flags & (1 << i))
  			seq_printf(m, "%s\n", trace_options[i]);
  		else
  			seq_printf(m, "no%s\n", trace_options[i]);
  	}
  
  	for (i = 0; trace_opts[i].name; i++) {
  		if (tracer_flags & trace_opts[i].bit)
  			seq_printf(m, "%s\n", trace_opts[i].name);
  		else
  			seq_printf(m, "no%s\n", trace_opts[i].name);
  	}
  	mutex_unlock(&trace_types_lock);
  
  	return 0;
  }
  
  static int __set_tracer_option(struct tracer *trace,
  			       struct tracer_flags *tracer_flags,
  			       struct tracer_opt *opts, int neg)
  {
  	int ret;
  
  	ret = trace->set_flag(tracer_flags->val, opts->bit, !neg);
  	if (ret)
  		return ret;
  
  	if (neg)
  		tracer_flags->val &= ~opts->bit;
  	else
  		tracer_flags->val |= opts->bit;
  	return 0;
  }
  
  /* Try to assign a tracer specific option */
  static int set_tracer_option(struct tracer *trace, char *cmp, int neg)
  {
  	struct tracer_flags *tracer_flags = trace->flags;
  	struct tracer_opt *opts = NULL;
  	int i;
  
  	for (i = 0; tracer_flags->opts[i].name; i++) {
  		opts = &tracer_flags->opts[i];
  
  		if (strcmp(cmp, opts->name) == 0)
  			return __set_tracer_option(trace, trace->flags,
  						   opts, neg);
  	}
  
  	return -EINVAL;
  }
  
  static void set_tracer_flags(unsigned int mask, int enabled)
  {
  	/* do nothing if flag is already set */
  	if (!!(trace_flags & mask) == !!enabled)
  		return;
  
  	if (enabled)
  		trace_flags |= mask;
  	else
  		trace_flags &= ~mask;
  }
  
  static ssize_t
  tracing_trace_options_write(struct file *filp, const char __user *ubuf,
  			size_t cnt, loff_t *ppos)
  {
  	char buf[64];
  	char *cmp;
  	int neg = 0;
  	int ret;
  	int i;
  
  	if (cnt >= sizeof(buf))
  		return -EINVAL;
  
  	if (copy_from_user(&buf, ubuf, cnt))
  		return -EFAULT;
  
  	buf[cnt] = 0;
  	cmp = strstrip(buf);
  
  	if (strncmp(cmp, "no", 2) == 0) {
  		neg = 1;
  		cmp += 2;
  	}
  
  	for (i = 0; trace_options[i]; i++) {
  		if (strcmp(cmp, trace_options[i]) == 0) {
  			set_tracer_flags(1 << i, !neg);
  			break;
  		}
  	}
  
  	/* If no option could be set, test the specific tracer options */
  	if (!trace_options[i]) {
  		mutex_lock(&trace_types_lock);
  		ret = set_tracer_option(current_trace, cmp, neg);
  		mutex_unlock(&trace_types_lock);
  		if (ret)
  			return ret;
  	}
  
  	*ppos += cnt;
  
  	return cnt;
  }
  
  static int tracing_trace_options_open(struct inode *inode, struct file *file)
  {
  	if (tracing_disabled)
  		return -ENODEV;
  	return single_open(file, tracing_trace_options_show, NULL);
  }
  
  static const struct file_operations tracing_iter_fops = {
  	.open		= tracing_trace_options_open,
  	.read		= seq_read,
  	.llseek		= seq_lseek,
  	.release	= single_release,
  	.write		= tracing_trace_options_write,
  };
  
  static const char readme_msg[] =
  	"tracing mini-HOWTO:\n\n"
  	"# mount -t debugfs nodev /sys/kernel/debug\n\n"
  	"# cat /sys/kernel/debug/tracing/available_tracers\n"
  	"wakeup preemptirqsoff preemptoff irqsoff function sched_switch nop\n\n"
  	"# cat /sys/kernel/debug/tracing/current_tracer\n"
  	"nop\n"
  	"# echo sched_switch > /sys/kernel/debug/tracing/current_tracer\n"
  	"# cat /sys/kernel/debug/tracing/current_tracer\n"
  	"sched_switch\n"
  	"# cat /sys/kernel/debug/tracing/trace_options\n"
  	"noprint-parent nosym-offset nosym-addr noverbose\n"
  	"# echo print-parent > /sys/kernel/debug/tracing/trace_options\n"
  	"# echo 1 > /sys/kernel/debug/tracing/tracing_enabled\n"
  	"# cat /sys/kernel/debug/tracing/trace > /tmp/trace.txt\n"
  	"# echo 0 > /sys/kernel/debug/tracing/tracing_enabled\n"
  ;
  
  static ssize_t
  tracing_readme_read(struct file *filp, char __user *ubuf,
  		       size_t cnt, loff_t *ppos)
  {
  	return simple_read_from_buffer(ubuf, cnt, ppos,
  					readme_msg, strlen(readme_msg));
  }
  
  static const struct file_operations tracing_readme_fops = {
  	.open		= tracing_open_generic,
  	.read		= tracing_readme_read,
  };
  
  static ssize_t
  tracing_saved_cmdlines_read(struct file *file, char __user *ubuf,
  				size_t cnt, loff_t *ppos)
  {
  	char *buf_comm;
  	char *file_buf;
  	char *buf;
  	int len = 0;
  	int pid;
  	int i;
  
  	file_buf = kmalloc(SAVED_CMDLINES*(16+TASK_COMM_LEN), GFP_KERNEL);
  	if (!file_buf)
  		return -ENOMEM;
  
  	buf_comm = kmalloc(TASK_COMM_LEN, GFP_KERNEL);
  	if (!buf_comm) {
  		kfree(file_buf);
  		return -ENOMEM;
  	}
  
  	buf = file_buf;
  
  	for (i = 0; i < SAVED_CMDLINES; i++) {
  		int r;
  
  		pid = map_cmdline_to_pid[i];
  		if (pid == -1 || pid == NO_CMDLINE_MAP)
  			continue;
  
  		trace_find_cmdline(pid, buf_comm);
  		r = sprintf(buf, "%d %s\n", pid, buf_comm);
  		buf += r;
  		len += r;
  	}
  
  	len = simple_read_from_buffer(ubuf, cnt, ppos,
  				      file_buf, len);
  
  	kfree(file_buf);
  	kfree(buf_comm);
  
  	return len;
  }
  
  static const struct file_operations tracing_saved_cmdlines_fops = {
      .open       = tracing_open_generic,
      .read       = tracing_saved_cmdlines_read,
  };
  
  static ssize_t
  tracing_ctrl_read(struct file *filp, char __user *ubuf,
  		  size_t cnt, loff_t *ppos)
  {
  	char buf[64];
  	int r;
  
  	r = sprintf(buf, "%u\n", tracer_enabled);
  	return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
  }
  
  static ssize_t
  tracing_ctrl_write(struct file *filp, const char __user *ubuf,
  		   size_t cnt, loff_t *ppos)
  {
  	struct trace_array *tr = filp->private_data;
  	char buf[64];
  	unsigned long val;
  	int ret;
  
  	if (cnt >= sizeof(buf))
  		return -EINVAL;
  
  	if (copy_from_user(&buf, ubuf, cnt))
  		return -EFAULT;
  
  	buf[cnt] = 0;
  
  	ret = strict_strtoul(buf, 10, &val);
  	if (ret < 0)
  		return ret;
  
  	val = !!val;
  
  	mutex_lock(&trace_types_lock);
  	if (tracer_enabled ^ val) {
  		if (val) {
  			tracer_enabled = 1;
  			if (current_trace->start)
  				current_trace->start(tr);
  			tracing_start();
  		} else {
  			tracer_enabled = 0;
  			tracing_stop();
  			if (current_trace->stop)
  				current_trace->stop(tr);
  		}
  	}
  	mutex_unlock(&trace_types_lock);
  
  	*ppos += cnt;
  
  	return cnt;
  }
  
  static ssize_t
  tracing_set_trace_read(struct file *filp, char __user *ubuf,
  		       size_t cnt, loff_t *ppos)
  {
  	char buf[MAX_TRACER_SIZE+2];
  	int r;
  
  	mutex_lock(&trace_types_lock);
  	if (current_trace)
  		r = sprintf(buf, "%s\n", current_trace->name);
  	else
  		r = sprintf(buf, "\n");
  	mutex_unlock(&trace_types_lock);
  
  	return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
  }
  
  int tracer_init(struct tracer *t, struct trace_array *tr)
  {
  	tracing_reset_online_cpus(tr);
  	return t->init(tr);
  }
  
  static int tracing_resize_ring_buffer(unsigned long size)
  {
  	int ret;
  
  	/*
  	 * If kernel or user changes the size of the ring buffer
  	 * we use the size that was given, and we can forget about
  	 * expanding it later.
  	 */
  	ring_buffer_expanded = 1;
  
  	ret = ring_buffer_resize(global_trace.buffer, size);
  	if (ret < 0)
  		return ret;
  
  	ret = ring_buffer_resize(max_tr.buffer, size);
  	if (ret < 0) {
  		int r;
  
  		r = ring_buffer_resize(global_trace.buffer,
  				       global_trace.entries);
  		if (r < 0) {
  			/*
  			 * AARGH! We are left with different
  			 * size max buffer!!!!
  			 * The max buffer is our "snapshot" buffer.
  			 * When a tracer needs a snapshot (one of the
  			 * latency tracers), it swaps the max buffer
  			 * with the saved snap shot. We succeeded to
  			 * update the size of the main buffer, but failed to
  			 * update the size of the max buffer. But when we tried
  			 * to reset the main buffer to the original size, we
  			 * failed there too. This is very unlikely to
  			 * happen, but if it does, warn and kill all
  			 * tracing.
  			 */
  			WARN_ON(1);
  			tracing_disabled = 1;
  		}
  		return ret;
  	}
  
  	global_trace.entries = size;
  
  	return ret;
  }
  
  /**
   * tracing_update_buffers - used by tracing facility to expand ring buffers
   *
   * To save on memory when the tracing is never used on a system with it
   * configured in. The ring buffers are set to a minimum size. But once
   * a user starts to use the tracing facility, then they need to grow
   * to their default size.
   *
   * This function is to be called when a tracer is about to be used.
   */
  int tracing_update_buffers(void)
  {
  	int ret = 0;
  
  	mutex_lock(&trace_types_lock);
  	if (!ring_buffer_expanded)
  		ret = tracing_resize_ring_buffer(trace_buf_size);
  	mutex_unlock(&trace_types_lock);
  
  	return ret;
  }
  
  struct trace_option_dentry;
  
  static struct trace_option_dentry *
  create_trace_option_files(struct tracer *tracer);
  
  static void
  destroy_trace_option_files(struct trace_option_dentry *topts);
  
  static int tracing_set_tracer(const char *buf)
  {
  	static struct trace_option_dentry *topts;
  	struct trace_array *tr = &global_trace;
  	struct tracer *t;
  	int ret = 0;
  
  	mutex_lock(&trace_types_lock);
  
  	if (!ring_buffer_expanded) {
  		ret = tracing_resize_ring_buffer(trace_buf_size);
  		if (ret < 0)
  			goto out;
  		ret = 0;
  	}
  
  	for (t = trace_types; t; t = t->next) {
  		if (strcmp(t->name, buf) == 0)
  			break;
  	}
  	if (!t) {
  		ret = -EINVAL;
  		goto out;
  	}
  	if (t == current_trace)
  		goto out;
  
  	trace_branch_disable();
  	if (current_trace && current_trace->reset)
  		current_trace->reset(tr);
  
  	destroy_trace_option_files(topts);
  
  	current_trace = t;
  
  	topts = create_trace_option_files(current_trace);
  
  	if (t->init) {
  		ret = tracer_init(t, tr);
  		if (ret)
  			goto out;
  	}
  
  	trace_branch_enable(tr);
   out:
  	mutex_unlock(&trace_types_lock);
  
  	return ret;
  }
  
  static ssize_t
  tracing_set_trace_write(struct file *filp, const char __user *ubuf,
  			size_t cnt, loff_t *ppos)
  {
  	char buf[MAX_TRACER_SIZE+1];
  	int i;
  	size_t ret;
  	int err;
  
  	ret = cnt;
  
  	if (cnt > MAX_TRACER_SIZE)
  		cnt = MAX_TRACER_SIZE;
  
  	if (copy_from_user(&buf, ubuf, cnt))
  		return -EFAULT;
  
  	buf[cnt] = 0;
  
  	/* strip ending whitespace. */
  	for (i = cnt - 1; i > 0 && isspace(buf[i]); i--)
  		buf[i] = 0;
  
  	err = tracing_set_tracer(buf);
  	if (err)
  		return err;
  
  	*ppos += ret;
  
  	return ret;
  }
  
  static ssize_t
  tracing_max_lat_read(struct file *filp, char __user *ubuf,
  		     size_t cnt, loff_t *ppos)
  {
  	unsigned long *ptr = filp->private_data;
  	char buf[64];
  	int r;
  
  	r = snprintf(buf, sizeof(buf), "%ld\n",
  		     *ptr == (unsigned long)-1 ? -1 : nsecs_to_usecs(*ptr));
  	if (r > sizeof(buf))
  		r = sizeof(buf);
  	return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
  }
  
  static ssize_t
  tracing_max_lat_write(struct file *filp, const char __user *ubuf,
  		      size_t cnt, loff_t *ppos)
  {
  	unsigned long *ptr = filp->private_data;
  	char buf[64];
  	unsigned long val;
  	int ret;
  
  	if (cnt >= sizeof(buf))
  		return -EINVAL;
  
  	if (copy_from_user(&buf, ubuf, cnt))
  		return -EFAULT;
  
  	buf[cnt] = 0;
  
  	ret = strict_strtoul(buf, 10, &val);
  	if (ret < 0)
  		return ret;
  
  	*ptr = val * 1000;
  
  	return cnt;
  }
  
  static int tracing_open_pipe(struct inode *inode, struct file *filp)
  {
  	long cpu_file = (long) inode->i_private;
  	struct trace_iterator *iter;
  	int ret = 0;
  
  	if (tracing_disabled)
  		return -ENODEV;
  
  	mutex_lock(&trace_types_lock);
  
  	/* create a buffer to store the information to pass to userspace */
  	iter = kzalloc(sizeof(*iter), GFP_KERNEL);
  	if (!iter) {
  		ret = -ENOMEM;
  		goto out;
  	}
  
  	/*
  	 * We make a copy of the current tracer to avoid concurrent
  	 * changes on it while we are reading.
  	 */
  	iter->trace = kmalloc(sizeof(*iter->trace), GFP_KERNEL);
  	if (!iter->trace) {
  		ret = -ENOMEM;
  		goto fail;
  	}
  	if (current_trace)
  		*iter->trace = *current_trace;
  
  	if (!alloc_cpumask_var(&iter->started, GFP_KERNEL)) {
  		ret = -ENOMEM;
  		goto fail;
  	}
  
  	/* trace pipe does not show start of buffer */
  	cpumask_setall(iter->started);
  
  	if (trace_flags & TRACE_ITER_LATENCY_FMT)
  		iter->iter_flags |= TRACE_FILE_LAT_FMT;
  
  	iter->cpu_file = cpu_file;
  	iter->tr = &global_trace;
  	mutex_init(&iter->mutex);
  	filp->private_data = iter;
  
  	if (iter->trace->pipe_open)
  		iter->trace->pipe_open(iter);
  
  out:
  	mutex_unlock(&trace_types_lock);
  	return ret;
  
  fail:
  	kfree(iter->trace);
  	kfree(iter);
  	mutex_unlock(&trace_types_lock);
  	return ret;
  }
  
  static int tracing_release_pipe(struct inode *inode, struct file *file)
  {
  	struct trace_iterator *iter = file->private_data;
  
  	mutex_lock(&trace_types_lock);
  
  	if (iter->trace->pipe_close)
  		iter->trace->pipe_close(iter);
  
  	mutex_unlock(&trace_types_lock);
  
  	free_cpumask_var(iter->started);
  	mutex_destroy(&iter->mutex);
  	kfree(iter->trace);
  	kfree(iter);
  
  	return 0;
  }
  
  static unsigned int
  tracing_poll_pipe(struct file *filp, poll_table *poll_table)
  {
  	struct trace_iterator *iter = filp->private_data;
  
  	if (trace_flags & TRACE_ITER_BLOCK) {
  		/*
  		 * Always select as readable when in blocking mode
  		 */
  		return POLLIN | POLLRDNORM;
  	} else {
  		if (!trace_empty(iter))
  			return POLLIN | POLLRDNORM;
  		poll_wait(filp, &trace_wait, poll_table);
  		if (!trace_empty(iter))
  			return POLLIN | POLLRDNORM;
  
  		return 0;
  	}
  }
  
  
  void default_wait_pipe(struct trace_iterator *iter)
  {
  	DEFINE_WAIT(wait);
  
  	prepare_to_wait(&trace_wait, &wait, TASK_INTERRUPTIBLE);
  
  	if (trace_empty(iter))
  		schedule();
  
  	finish_wait(&trace_wait, &wait);
  }
  
  /*
   * This is a make-shift waitqueue.
   * A tracer might use this callback on some rare cases:
   *
   *  1) the current tracer might hold the runqueue lock when it wakes up
   *     a reader, hence a deadlock (sched, function, and function graph tracers)
   *  2) the function tracers, trace all functions, we don't want
   *     the overhead of calling wake_up and friends
   *     (and tracing them too)
   *
   *     Anyway, this is really very primitive wakeup.
   */
  void poll_wait_pipe(struct trace_iterator *iter)
  {
  	set_current_state(TASK_INTERRUPTIBLE);
  	/* sleep for 100 msecs, and try again. */
  	schedule_timeout(HZ / 10);
  }
  
  /* Must be called with trace_types_lock mutex held. */
  static int tracing_wait_pipe(struct file *filp)
  {
  	struct trace_iterator *iter = filp->private_data;
  
  	while (trace_empty(iter)) {
  
  		if ((filp->f_flags & O_NONBLOCK)) {
  			return -EAGAIN;
  		}
  
  		mutex_unlock(&iter->mutex);
  
  		iter->trace->wait_pipe(iter);
  
  		mutex_lock(&iter->mutex);
  
  		if (signal_pending(current))
  			return -EINTR;
  
  		/*
  		 * We block until we read something and tracing is disabled.
  		 * We still block if tracing is disabled, but we have never
  		 * read anything. This allows a user to cat this file, and
  		 * then enable tracing. But after we have read something,
  		 * we give an EOF when tracing is again disabled.
  		 *
  		 * iter->pos will be 0 if we haven't read anything.
  		 */
  		if (!tracer_enabled && iter->pos)
  			break;
  	}
  
  	return 1;
  }
  
  /*
   * Consumer reader.
   */
  static ssize_t
  tracing_read_pipe(struct file *filp, char __user *ubuf,
  		  size_t cnt, loff_t *ppos)
  {
  	struct trace_iterator *iter = filp->private_data;
  	static struct tracer *old_tracer;
  	ssize_t sret;
  
  	/* return any leftover data */
  	sret = trace_seq_to_user(&iter->seq, ubuf, cnt);
  	if (sret != -EBUSY)
  		return sret;
  
  	trace_seq_init(&iter->seq);
  
  	/* copy the tracer to avoid using a global lock all around */
  	mutex_lock(&trace_types_lock);
  	if (unlikely(old_tracer != current_trace && current_trace)) {
  		old_tracer = current_trace;
  		*iter->trace = *current_trace;
  	}
  	mutex_unlock(&trace_types_lock);
  
  	/*
  	 * Avoid more than one consumer on a single file descriptor
  	 * This is just a matter of traces coherency, the ring buffer itself
  	 * is protected.
  	 */
  	mutex_lock(&iter->mutex);
  	if (iter->trace->read) {
  		sret = iter->trace->read(iter, filp, ubuf, cnt, ppos);
  		if (sret)
  			goto out;
  	}
  
  waitagain:
  	sret = tracing_wait_pipe(filp);
  	if (sret <= 0)
  		goto out;
  
  	/* stop when tracing is finished */
  	if (trace_empty(iter)) {
  		sret = 0;
  		goto out;
  	}
  
  	if (cnt >= PAGE_SIZE)
  		cnt = PAGE_SIZE - 1;
  
  	/* reset all but tr, trace, and overruns */
  	memset(&iter->seq, 0,
  	       sizeof(struct trace_iterator) -
  	       offsetof(struct trace_iterator, seq));
  	iter->pos = -1;
  
  	trace_event_read_lock();
  	trace_access_lock(iter->cpu_file);
  	while (find_next_entry_inc(iter) != NULL) {
  		enum print_line_t ret;
  		int len = iter->seq.len;
  
  		ret = print_trace_line(iter);
  		if (ret == TRACE_TYPE_PARTIAL_LINE) {
  			/* don't print partial lines */
  			iter->seq.len = len;
  			break;
  		}
  		if (ret != TRACE_TYPE_NO_CONSUME)
  			trace_consume(iter);
  
  		if (iter->seq.len >= cnt)
  			break;
  	}
  	trace_access_unlock(iter->cpu_file);
  	trace_event_read_unlock();
  
  	/* Now copy what we have to the user */
  	sret = trace_seq_to_user(&iter->seq, ubuf, cnt);
  	if (iter->seq.readpos >= iter->seq.len)
  		trace_seq_init(&iter->seq);
  
  	/*
  	 * If there was nothing to send to user, inspite of consuming trace
  	 * entries, go back to wait for more entries.
  	 */
  	if (sret == -EBUSY)
  		goto waitagain;
  
  out:
  	mutex_unlock(&iter->mutex);
  
  	return sret;
  }
  
  static void tracing_pipe_buf_release(struct pipe_inode_info *pipe,
  				     struct pipe_buffer *buf)
  {
  	__free_page(buf->page);
  }
  
  static void tracing_spd_release_pipe(struct splice_pipe_desc *spd,
  				     unsigned int idx)
  {
  	__free_page(spd->pages[idx]);
  }
  
  static const struct pipe_buf_operations tracing_pipe_buf_ops = {
  	.can_merge		= 0,
  	.map			= generic_pipe_buf_map,
  	.unmap			= generic_pipe_buf_unmap,
  	.confirm		= generic_pipe_buf_confirm,
  	.release		= tracing_pipe_buf_release,
  	.steal			= generic_pipe_buf_steal,
  	.get			= generic_pipe_buf_get,
  };
  
  static size_t
  tracing_fill_pipe_page(size_t rem, struct trace_iterator *iter)
  {
  	size_t count;
  	int ret;
  
  	/* Seq buffer is page-sized, exactly what we need. */
  	for (;;) {
  		count = iter->seq.len;
  		ret = print_trace_line(iter);
  		count = iter->seq.len - count;
  		if (rem < count) {
  			rem = 0;
  			iter->seq.len -= count;
  			break;
  		}
  		if (ret == TRACE_TYPE_PARTIAL_LINE) {
  			iter->seq.len -= count;
  			break;
  		}
  
  		if (ret != TRACE_TYPE_NO_CONSUME)
  			trace_consume(iter);
  		rem -= count;
  		if (!find_next_entry_inc(iter))	{
  			rem = 0;
  			iter->ent = NULL;
  			break;
  		}
  	}
  
  	return rem;
  }
  
  static ssize_t tracing_splice_read_pipe(struct file *filp,
  					loff_t *ppos,
  					struct pipe_inode_info *pipe,
  					size_t len,
  					unsigned int flags)
  {
  	struct page *pages[PIPE_BUFFERS];
  	struct partial_page partial[PIPE_BUFFERS];
  	struct trace_iterator *iter = filp->private_data;
  	struct splice_pipe_desc spd = {
  		.pages		= pages,
  		.partial	= partial,
  		.nr_pages	= 0, /* This gets updated below. */
  		.flags		= flags,
  		.ops		= &tracing_pipe_buf_ops,
  		.spd_release	= tracing_spd_release_pipe,
  	};
  	static struct tracer *old_tracer;
  	ssize_t ret;
  	size_t rem;
  	unsigned int i;
  
  	/* copy the tracer to avoid using a global lock all around */
  	mutex_lock(&trace_types_lock);
  	if (unlikely(old_tracer != current_trace && current_trace)) {
  		old_tracer = current_trace;
  		*iter->trace = *current_trace;
  	}
  	mutex_unlock(&trace_types_lock);
  
  	mutex_lock(&iter->mutex);
  
  	if (iter->trace->splice_read) {
  		ret = iter->trace->splice_read(iter, filp,
  					       ppos, pipe, len, flags);
  		if (ret)
  			goto out_err;
  	}
  
  	ret = tracing_wait_pipe(filp);
  	if (ret <= 0)
  		goto out_err;
  
  	if (!iter->ent && !find_next_entry_inc(iter)) {
  		ret = -EFAULT;
  		goto out_err;
  	}
  
  	trace_event_read_lock();
  	trace_access_lock(iter->cpu_file);
  
  	/* Fill as many pages as possible. */
  	for (i = 0, rem = len; i < PIPE_BUFFERS && rem; i++) {
  		pages[i] = alloc_page(GFP_KERNEL);
  		if (!pages[i])
  			break;
  
  		rem = tracing_fill_pipe_page(rem, iter);
  
  		/* Copy the data into the page, so we can start over. */
  		ret = trace_seq_to_buffer(&iter->seq,
  					  page_address(pages[i]),
  					  iter->seq.len);
  		if (ret < 0) {
  			__free_page(pages[i]);
  			break;
  		}
  		partial[i].offset = 0;
  		partial[i].len = iter->seq.len;
  
  		trace_seq_init(&iter->seq);
  	}
  
  	trace_access_unlock(iter->cpu_file);
  	trace_event_read_unlock();
  	mutex_unlock(&iter->mutex);
  
  	spd.nr_pages = i;
  
  	return splice_to_pipe(pipe, &spd);
  
  out_err:
  	mutex_unlock(&iter->mutex);
  
  	return ret;
  }
  
  static ssize_t
  tracing_entries_read(struct file *filp, char __user *ubuf,
  		     size_t cnt, loff_t *ppos)
  {
  	struct trace_array *tr = filp->private_data;
  	char buf[96];
  	int r;
  
  	mutex_lock(&trace_types_lock);
  	if (!ring_buffer_expanded)
  		r = sprintf(buf, "%lu (expanded: %lu)\n",
  			    tr->entries >> 10,
  			    trace_buf_size >> 10);
  	else
  		r = sprintf(buf, "%lu\n", tr->entries >> 10);
  	mutex_unlock(&trace_types_lock);
  
  	return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
  }
  
  static ssize_t
  tracing_entries_write(struct file *filp, const char __user *ubuf,
  		      size_t cnt, loff_t *ppos)
  {
  	unsigned long val;
  	char buf[64];
  	int ret, cpu;
  
  	if (cnt >= sizeof(buf))
  		return -EINVAL;
  
  	if (copy_from_user(&buf, ubuf, cnt))
  		return -EFAULT;
  
  	buf[cnt] = 0;
  
  	ret = strict_strtoul(buf, 10, &val);
  	if (ret < 0)
  		return ret;
  
  	/* must have at least 1 entry */
  	if (!val)
  		return -EINVAL;
  
  	mutex_lock(&trace_types_lock);
  
  	tracing_stop();
  
  	/* disable all cpu buffers */
  	for_each_tracing_cpu(cpu) {
  		if (global_trace.data[cpu])
  			atomic_inc(&global_trace.data[cpu]->disabled);
  		if (max_tr.data[cpu])
  			atomic_inc(&max_tr.data[cpu]->disabled);
  	}
  
  	/* value is in KB */
  	val <<= 10;
  
  	if (val != global_trace.entries) {
  		ret = tracing_resize_ring_buffer(val);
  		if (ret < 0) {
  			cnt = ret;
  			goto out;
  		}
  	}
  
  	*ppos += cnt;
  
  	/* If check pages failed, return ENOMEM */
  	if (tracing_disabled)
  		cnt = -ENOMEM;
   out:
  	for_each_tracing_cpu(cpu) {
  		if (global_trace.data[cpu])
  			atomic_dec(&global_trace.data[cpu]->disabled);
  		if (max_tr.data[cpu])
  			atomic_dec(&max_tr.data[cpu]->disabled);
  	}
  
  	tracing_start();
  	max_tr.entries = global_trace.entries;
  	mutex_unlock(&trace_types_lock);
  
  	return cnt;
  }
  
  static int mark_printk(const char *fmt, ...)
  {
  	int ret;
  	va_list args;
  	va_start(args, fmt);
  	ret = trace_vprintk(0, fmt, args);
  	va_end(args);
  	return ret;
  }
  
  static ssize_t
  tracing_mark_write(struct file *filp, const char __user *ubuf,
  					size_t cnt, loff_t *fpos)
  {
  	char *buf;
  
  	if (tracing_disabled)
  		return -EINVAL;
  
  	if (cnt > TRACE_BUF_SIZE)
  		cnt = TRACE_BUF_SIZE;
  
  	buf = kmalloc(cnt + 2, GFP_KERNEL);
  	if (buf == NULL)
  		return -ENOMEM;
  
  	if (copy_from_user(buf, ubuf, cnt)) {
  		kfree(buf);
  		return -EFAULT;
  	}
  	if (buf[cnt-1] != '\n') {
  		buf[cnt] = '\n';
  		buf[cnt+1] = '\0';
  	} else
  		buf[cnt] = '\0';
  
  	cnt = mark_printk("%s", buf);
  	kfree(buf);
  	*fpos += cnt;
  
  	return cnt;
  }
  
  static int tracing_clock_show(struct seq_file *m, void *v)
  {
  	int i;
  
  	for (i = 0; i < ARRAY_SIZE(trace_clocks); i++)
  		seq_printf(m,
  			"%s%s%s%s", i ? " " : "",
  			i == trace_clock_id ? "[" : "", trace_clocks[i].name,
  			i == trace_clock_id ? "]" : "");
  	seq_putc(m, '\n');
  
  	return 0;
  }
  
  static ssize_t tracing_clock_write(struct file *filp, const char __user *ubuf,
  				   size_t cnt, loff_t *fpos)
  {
  	char buf[64];
  	const char *clockstr;
  	int i;
  
  	if (cnt >= sizeof(buf))
  		return -EINVAL;
  
  	if (copy_from_user(&buf, ubuf, cnt))
  		return -EFAULT;
  
  	buf[cnt] = 0;
  
  	clockstr = strstrip(buf);
  
  	for (i = 0; i < ARRAY_SIZE(trace_clocks); i++) {
  		if (strcmp(trace_clocks[i].name, clockstr) == 0)
  			break;
  	}
  	if (i == ARRAY_SIZE(trace_clocks))
  		return -EINVAL;
  
  	trace_clock_id = i;
  
  	mutex_lock(&trace_types_lock);
  
  	ring_buffer_set_clock(global_trace.buffer, trace_clocks[i].func);
  	if (max_tr.buffer)
  		ring_buffer_set_clock(max_tr.buffer, trace_clocks[i].func);
  
  	mutex_unlock(&trace_types_lock);
  
  	*fpos += cnt;
  
  	return cnt;
  }
  
  static int tracing_clock_open(struct inode *inode, struct file *file)
  {
  	if (tracing_disabled)
  		return -ENODEV;
  	return single_open(file, tracing_clock_show, NULL);
  }
  
  static const struct file_operations tracing_max_lat_fops = {
  	.open		= tracing_open_generic,
  	.read		= tracing_max_lat_read,
  	.write		= tracing_max_lat_write,
  };
  
  static const struct file_operations tracing_ctrl_fops = {
  	.open		= tracing_open_generic,
  	.read		= tracing_ctrl_read,
  	.write		= tracing_ctrl_write,
  };
  
  static const struct file_operations set_tracer_fops = {
  	.open		= tracing_open_generic,
  	.read		= tracing_set_trace_read,
  	.write		= tracing_set_trace_write,
  };
  
  static const struct file_operations tracing_pipe_fops = {
  	.open		= tracing_open_pipe,
  	.poll		= tracing_poll_pipe,
  	.read		= tracing_read_pipe,
  	.splice_read	= tracing_splice_read_pipe,
  	.release	= tracing_release_pipe,
  };
  
  static const struct file_operations tracing_entries_fops = {
  	.open		= tracing_open_generic,
  	.read		= tracing_entries_read,
  	.write		= tracing_entries_write,
  };
  
  static const struct file_operations tracing_mark_fops = {
  	.open		= tracing_open_generic,
  	.write		= tracing_mark_write,
  };
  
  static const struct file_operations trace_clock_fops = {
  	.open		= tracing_clock_open,
  	.read		= seq_read,
  	.llseek		= seq_lseek,
  	.release	= single_release,
  	.write		= tracing_clock_write,
  };
  
  struct ftrace_buffer_info {
  	struct trace_array	*tr;
  	void			*spare;
  	int			cpu;
  	unsigned int		read;
  };
  
  static int tracing_buffers_open(struct inode *inode, struct file *filp)
  {
  	int cpu = (int)(long)inode->i_private;
  	struct ftrace_buffer_info *info;
  
  	if (tracing_disabled)
  		return -ENODEV;
  
  	info = kzalloc(sizeof(*info), GFP_KERNEL);
  	if (!info)
  		return -ENOMEM;
  
  	info->tr	= &global_trace;
  	info->cpu	= cpu;
  	info->spare	= NULL;
  	/* Force reading ring buffer for first read */
  	info->read	= (unsigned int)-1;
  
  	filp->private_data = info;
  
  	return nonseekable_open(inode, filp);
  }
  
  static ssize_t
  tracing_buffers_read(struct file *filp, char __user *ubuf,
  		     size_t count, loff_t *ppos)
  {
  	struct ftrace_buffer_info *info = filp->private_data;
  	unsigned int pos;
  	ssize_t ret;
  	size_t size;
  
  	if (!count)
  		return 0;
  
  	if (!info->spare)
  		info->spare = ring_buffer_alloc_read_page(info->tr->buffer);
  	if (!info->spare)
  		return -ENOMEM;
  
  	/* Do we have previous read data to read? */
  	if (info->read < PAGE_SIZE)
  		goto read;
  
  	info->read = 0;
  
  	trace_access_lock(info->cpu);
  	ret = ring_buffer_read_page(info->tr->buffer,
  				    &info->spare,
  				    count,
  				    info->cpu, 0);
  	trace_access_unlock(info->cpu);
  	if (ret < 0)
  		return 0;
  
  	pos = ring_buffer_page_len(info->spare);
  
  	if (pos < PAGE_SIZE)
  		memset(info->spare + pos, 0, PAGE_SIZE - pos);
  
  read:
  	size = PAGE_SIZE - info->read;
  	if (size > count)
  		size = count;
  
  	ret = copy_to_user(ubuf, info->spare + info->read, size);
  	if (ret == size)
  		return -EFAULT;
  	size -= ret;
  
  	*ppos += size;
  	info->read += size;
  
  	return size;
  }
  
  static int tracing_buffers_release(struct inode *inode, struct file *file)
  {
  	struct ftrace_buffer_info *info = file->private_data;
  
  	if (info->spare)
  		ring_buffer_free_read_page(info->tr->buffer, info->spare);
  	kfree(info);
  
  	return 0;
  }
  
  struct buffer_ref {
  	struct ring_buffer	*buffer;
  	void			*page;
  	int			ref;
  };
  
  static void buffer_pipe_buf_release(struct pipe_inode_info *pipe,
  				    struct pipe_buffer *buf)
  {
  	struct buffer_ref *ref = (struct buffer_ref *)buf->private;
  
  	if (--ref->ref)
  		return;
  
  	ring_buffer_free_read_page(ref->buffer, ref->page);
  	kfree(ref);
  	buf->private = 0;
  }
  
  static int buffer_pipe_buf_steal(struct pipe_inode_info *pipe,
  				 struct pipe_buffer *buf)
  {
  	return 1;
  }
  
  static void buffer_pipe_buf_get(struct pipe_inode_info *pipe,
  				struct pipe_buffer *buf)
  {
  	struct buffer_ref *ref = (struct buffer_ref *)buf->private;
  
  	ref->ref++;
  }
  
  /* Pipe buffer operations for a buffer. */
  static const struct pipe_buf_operations buffer_pipe_buf_ops = {
  	.can_merge		= 0,
  	.map			= generic_pipe_buf_map,
  	.unmap			= generic_pipe_buf_unmap,
  	.confirm		= generic_pipe_buf_confirm,
  	.release		= buffer_pipe_buf_release,
  	.steal			= buffer_pipe_buf_steal,
  	.get			= buffer_pipe_buf_get,
  };
  
  /*
   * Callback from splice_to_pipe(), if we need to release some pages
   * at the end of the spd in case we error'ed out in filling the pipe.
   */
  static void buffer_spd_release(struct splice_pipe_desc *spd, unsigned int i)
  {
  	struct buffer_ref *ref =
  		(struct buffer_ref *)spd->partial[i].private;
  
  	if (--ref->ref)
  		return;
  
  	ring_buffer_free_read_page(ref->buffer, ref->page);
  	kfree(ref);
  	spd->partial[i].private = 0;
  }
  
  static ssize_t
  tracing_buffers_splice_read(struct file *file, loff_t *ppos,
  			    struct pipe_inode_info *pipe, size_t len,
  			    unsigned int flags)
  {
  	struct ftrace_buffer_info *info = file->private_data;
  	struct partial_page partial[PIPE_BUFFERS];
  	struct page *pages[PIPE_BUFFERS];
  	struct splice_pipe_desc spd = {
  		.pages		= pages,
  		.partial	= partial,
  		.flags		= flags,
  		.ops		= &buffer_pipe_buf_ops,
  		.spd_release	= buffer_spd_release,
  	};
  	struct buffer_ref *ref;
  	int entries, size, i;
  	size_t ret;
  
  	if (*ppos & (PAGE_SIZE - 1)) {
  		WARN_ONCE(1, "Ftrace: previous read must page-align\n");
  		return -EINVAL;
  	}
  
  	if (len & (PAGE_SIZE - 1)) {
  		WARN_ONCE(1, "Ftrace: splice_read should page-align\n");
  		if (len < PAGE_SIZE)
  			return -EINVAL;
  		len &= PAGE_MASK;
  	}
  
  	trace_access_lock(info->cpu);
  	entries = ring_buffer_entries_cpu(info->tr->buffer, info->cpu);
  
  	for (i = 0; i < PIPE_BUFFERS && len && entries; i++, len -= PAGE_SIZE) {
  		struct page *page;
  		int r;
  
  		ref = kzalloc(sizeof(*ref), GFP_KERNEL);
  		if (!ref)
  			break;
  
  		ref->ref = 1;
  		ref->buffer = info->tr->buffer;
  		ref->page = ring_buffer_alloc_read_page(ref->buffer);
  		if (!ref->page) {
  			kfree(ref);
  			break;
  		}
  
  		r = ring_buffer_read_page(ref->buffer, &ref->page,
  					  len, info->cpu, 1);
  		if (r < 0) {
  			ring_buffer_free_read_page(ref->buffer,
  						   ref->page);
  			kfree(ref);
  			break;
  		}
  
  		/*
  		 * zero out any left over data, this is going to
  		 * user land.
  		 */
  		size = ring_buffer_page_len(ref->page);
  		if (size < PAGE_SIZE)
  			memset(ref->page + size, 0, PAGE_SIZE - size);
  
  		page = virt_to_page(ref->page);
  
  		spd.pages[i] = page;
  		spd.partial[i].len = PAGE_SIZE;
  		spd.partial[i].offset = 0;
  		spd.partial[i].private = (unsigned long)ref;
  		spd.nr_pages++;
  		*ppos += PAGE_SIZE;
  
  		entries = ring_buffer_entries_cpu(info->tr->buffer, info->cpu);
  	}
  
  	trace_access_unlock(info->cpu);
  	spd.nr_pages = i;
  
  	/* did we read anything? */
  	if (!spd.nr_pages) {
  		if (flags & SPLICE_F_NONBLOCK)
  			ret = -EAGAIN;
  		else
  			ret = 0;
  		/* TODO: block */
  		return ret;
  	}
  
  	ret = splice_to_pipe(pipe, &spd);
  
  	return ret;
  }
  
  static const struct file_operations tracing_buffers_fops = {
  	.open		= tracing_buffers_open,
  	.read		= tracing_buffers_read,
  	.release	= tracing_buffers_release,
  	.splice_read	= tracing_buffers_splice_read,
  	.llseek		= no_llseek,
  };
  
  static ssize_t
  tracing_stats_read(struct file *filp, char __user *ubuf,
  		   size_t count, loff_t *ppos)
  {
  	unsigned long cpu = (unsigned long)filp->private_data;
  	struct trace_array *tr = &global_trace;
  	struct trace_seq *s;
  	unsigned long cnt;
  
  	s = kmalloc(sizeof(*s), GFP_KERNEL);
  	if (!s)
  		return -ENOMEM;
  
  	trace_seq_init(s);
  
  	cnt = ring_buffer_entries_cpu(tr->buffer, cpu);
  	trace_seq_printf(s, "entries: %ld\n", cnt);
  
  	cnt = ring_buffer_overrun_cpu(tr->buffer, cpu);
  	trace_seq_printf(s, "overrun: %ld\n", cnt);
  
  	cnt = ring_buffer_commit_overrun_cpu(tr->buffer, cpu);
  	trace_seq_printf(s, "commit overrun: %ld\n", cnt);
  
  	count = simple_read_from_buffer(ubuf, count, ppos, s->buffer, s->len);
  
  	kfree(s);
  
  	return count;
  }
  
  static const struct file_operations tracing_stats_fops = {
  	.open		= tracing_open_generic,
  	.read		= tracing_stats_read,
  };
  
  #ifdef CONFIG_DYNAMIC_FTRACE
  
  int __weak ftrace_arch_read_dyn_info(char *buf, int size)
  {
  	return 0;
  }
  
  static ssize_t
  tracing_read_dyn_info(struct file *filp, char __user *ubuf,
  		  size_t cnt, loff_t *ppos)
  {
  	static char ftrace_dyn_info_buffer[1024];
  	static DEFINE_MUTEX(dyn_info_mutex);
  	unsigned long *p = filp->private_data;
  	char *buf = ftrace_dyn_info_buffer;
  	int size = ARRAY_SIZE(ftrace_dyn_info_buffer);
  	int r;
  
  	mutex_lock(&dyn_info_mutex);
  	r = sprintf(buf, "%ld ", *p);
  
  	r += ftrace_arch_read_dyn_info(buf+r, (size-1)-r);
  	buf[r++] = '\n';
  
  	r = simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
  
  	mutex_unlock(&dyn_info_mutex);
  
  	return r;
  }
  
  static const struct file_operations tracing_dyn_info_fops = {
  	.open		= tracing_open_generic,
  	.read		= tracing_read_dyn_info,
  };
  #endif
  
  static struct dentry *d_tracer;
  
  struct dentry *tracing_init_dentry(void)
  {
  	static int once;
  
  	if (d_tracer)
  		return d_tracer;
  
  	if (!debugfs_initialized())
  		return NULL;
  
  	d_tracer = debugfs_create_dir("tracing", NULL);
  
  	if (!d_tracer && !once) {
  		once = 1;
  		pr_warning("Could not create debugfs directory 'tracing'\n");
  		return NULL;
  	}
  
  	return d_tracer;
  }
  
  static struct dentry *d_percpu;
  
  struct dentry *tracing_dentry_percpu(void)
  {
  	static int once;
  	struct dentry *d_tracer;
  
  	if (d_percpu)
  		return d_percpu;
  
  	d_tracer = tracing_init_dentry();
  
  	if (!d_tracer)
  		return NULL;
  
  	d_percpu = debugfs_create_dir("per_cpu", d_tracer);
  
  	if (!d_percpu && !once) {
  		once = 1;
  		pr_warning("Could not create debugfs directory 'per_cpu'\n");
  		return NULL;
  	}
  
  	return d_percpu;
  }
  
  static void tracing_init_debugfs_percpu(long cpu)
  {
  	struct dentry *d_percpu = tracing_dentry_percpu();
  	struct dentry *d_cpu;
  	/* strlen(cpu) + MAX(log10(cpu)) + '\0' */
  	char cpu_dir[7];
  
  	if (cpu > 999 || cpu < 0)
  		return;
  
  	sprintf(cpu_dir, "cpu%ld", cpu);
  	d_cpu = debugfs_create_dir(cpu_dir, d_percpu);
  	if (!d_cpu) {
  		pr_warning("Could not create debugfs '%s' entry\n", cpu_dir);
  		return;
  	}
  
  	/* per cpu trace_pipe */
  	trace_create_file("trace_pipe", 0444, d_cpu,
  			(void *) cpu, &tracing_pipe_fops);
  
  	/* per cpu trace */
  	trace_create_file("trace", 0644, d_cpu,
  			(void *) cpu, &tracing_fops);
  
  	trace_create_file("trace_pipe_raw", 0444, d_cpu,
  			(void *) cpu, &tracing_buffers_fops);
  
  	trace_create_file("stats", 0444, d_cpu,
  			(void *) cpu, &tracing_stats_fops);
  }
  
  #ifdef CONFIG_FTRACE_SELFTEST
  /* Let selftest have access to static functions in this file */
  #include "trace_selftest.c"
  #endif
  
  struct trace_option_dentry {
  	struct tracer_opt		*opt;
  	struct tracer_flags		*flags;
  	struct dentry			*entry;
  };
  
  static ssize_t
  trace_options_read(struct file *filp, char __user *ubuf, size_t cnt,
  			loff_t *ppos)
  {
  	struct trace_option_dentry *topt = filp->private_data;
  	char *buf;
  
  	if (topt->flags->val & topt->opt->bit)
  		buf = "1\n";
  	else
  		buf = "0\n";
  
  	return simple_read_from_buffer(ubuf, cnt, ppos, buf, 2);
  }
  
  static ssize_t
  trace_options_write(struct file *filp, const char __user *ubuf, size_t cnt,
  			 loff_t *ppos)
  {
  	struct trace_option_dentry *topt = filp->private_data;
  	unsigned long val;
  	char buf[64];
  	int ret;
  
  	if (cnt >= sizeof(buf))
  		return -EINVAL;
  
  	if (copy_from_user(&buf, ubuf, cnt))
  		return -EFAULT;
  
  	buf[cnt] = 0;
  
  	ret = strict_strtoul(buf, 10, &val);
  	if (ret < 0)
  		return ret;
  
  	if (val != 0 && val != 1)
  		return -EINVAL;
  
  	if (!!(topt->flags->val & topt->opt->bit) != val) {
  		mutex_lock(&trace_types_lock);
  		ret = __set_tracer_option(current_trace, topt->flags,
  					  topt->opt, !val);
  		mutex_unlock(&trace_types_lock);
  		if (ret)
  			return ret;
  	}
  
  	*ppos += cnt;
  
  	return cnt;
  }
  
  
  static const struct file_operations trace_options_fops = {
  	.open = tracing_open_generic,
  	.read = trace_options_read,
  	.write = trace_options_write,
  };
  
  static ssize_t
  trace_options_core_read(struct file *filp, char __user *ubuf, size_t cnt,
  			loff_t *ppos)
  {
  	long index = (long)filp->private_data;
  	char *buf;
  
  	if (trace_flags & (1 << index))
  		buf = "1\n";
  	else
  		buf = "0\n";
  
  	return simple_read_from_buffer(ubuf, cnt, ppos, buf, 2);
  }
  
  static ssize_t
  trace_options_core_write(struct file *filp, const char __user *ubuf, size_t cnt,
  			 loff_t *ppos)
  {
  	long index = (long)filp->private_data;
  	char buf[64];
  	unsigned long val;
  	int ret;
  
  	if (cnt >= sizeof(buf))
  		return -EINVAL;
  
  	if (copy_from_user(&buf, ubuf, cnt))
  		return -EFAULT;
  
  	buf[cnt] = 0;
  
  	ret = strict_strtoul(buf, 10, &val);
  	if (ret < 0)
  		return ret;
  
  	if (val != 0 && val != 1)
  		return -EINVAL;
  	set_tracer_flags(1 << index, val);
  
  	*ppos += cnt;
  
  	return cnt;
  }
  
  static const struct file_operations trace_options_core_fops = {
  	.open = tracing_open_generic,
  	.read = trace_options_core_read,
  	.write = trace_options_core_write,
  };
  
  struct dentry *trace_create_file(const char *name,
  				 mode_t mode,
  				 struct dentry *parent,
  				 void *data,
  				 const struct file_operations *fops)
  {
  	struct dentry *ret;
  
  	ret = debugfs_create_file(name, mode, parent, data, fops);
  	if (!ret)
  		pr_warning("Could not create debugfs '%s' entry\n", name);
  
  	return ret;
  }
  
  
  static struct dentry *trace_options_init_dentry(void)
  {
  	struct dentry *d_tracer;
  	static struct dentry *t_options;
  
  	if (t_options)
  		return t_options;
  
  	d_tracer = tracing_init_dentry();
  	if (!d_tracer)
  		return NULL;
  
  	t_options = debugfs_create_dir("options", d_tracer);
  	if (!t_options) {
  		pr_warning("Could not create debugfs directory 'options'\n");
  		return NULL;
  	}
  
  	return t_options;
  }
  
  static void
  create_trace_option_file(struct trace_option_dentry *topt,
  			 struct tracer_flags *flags,
  			 struct tracer_opt *opt)
  {
  	struct dentry *t_options;
  
  	t_options = trace_options_init_dentry();
  	if (!t_options)
  		return;
  
  	topt->flags = flags;
  	topt->opt = opt;
  
  	topt->entry = trace_create_file(opt->name, 0644, t_options, topt,
  				    &trace_options_fops);
  
  }
  
  static struct trace_option_dentry *
  create_trace_option_files(struct tracer *tracer)
  {
  	struct trace_option_dentry *topts;
  	struct tracer_flags *flags;
  	struct tracer_opt *opts;
  	int cnt;
  
  	if (!tracer)
  		return NULL;
  
  	flags = tracer->flags;
  
  	if (!flags || !flags->opts)
  		return NULL;
  
  	opts = flags->opts;
  
  	for (cnt = 0; opts[cnt].name; cnt++)
  		;
  
  	topts = kcalloc(cnt + 1, sizeof(*topts), GFP_KERNEL);
  	if (!topts)
  		return NULL;
  
  	for (cnt = 0; opts[cnt].name; cnt++)
  		create_trace_option_file(&topts[cnt], flags,
  					 &opts[cnt]);
  
  	return topts;
  }
  
  static void
  destroy_trace_option_files(struct trace_option_dentry *topts)
  {
  	int cnt;
  
  	if (!topts)
  		return;
  
  	for (cnt = 0; topts[cnt].opt; cnt++) {
  		if (topts[cnt].entry)
  			debugfs_remove(topts[cnt].entry);
  	}
  
  	kfree(topts);
  }
  
  static struct dentry *
  create_trace_option_core_file(const char *option, long index)
  {
  	struct dentry *t_options;
  
  	t_options = trace_options_init_dentry();
  	if (!t_options)
  		return NULL;
  
  	return trace_create_file(option, 0644, t_options, (void *)index,
  				    &trace_options_core_fops);
  }
  
  static __init void create_trace_options_dir(void)
  {
  	struct dentry *t_options;
  	int i;
  
  	t_options = trace_options_init_dentry();
  	if (!t_options)
  		return;
  
  	for (i = 0; trace_options[i]; i++)
  		create_trace_option_core_file(trace_options[i], i);
  }
  
  static __init int tracer_init_debugfs(void)
  {
  	struct dentry *d_tracer;
  	int cpu;
  
  	trace_access_lock_init();
  
  	d_tracer = tracing_init_dentry();
  
  	trace_create_file("tracing_enabled", 0644, d_tracer,
  			&global_trace, &tracing_ctrl_fops);
  
  	trace_create_file("trace_options", 0644, d_tracer,
  			NULL, &tracing_iter_fops);
  
  	trace_create_file("tracing_cpumask", 0644, d_tracer,
  			NULL, &tracing_cpumask_fops);
  
  	trace_create_file("trace", 0644, d_tracer,
  			(void *) TRACE_PIPE_ALL_CPU, &tracing_fops);
  
  	trace_create_file("available_tracers", 0444, d_tracer,
  			&global_trace, &show_traces_fops);
  
  	trace_create_file("current_tracer", 0644, d_tracer,
  			&global_trace, &set_tracer_fops);
  
  #ifdef CONFIG_TRACER_MAX_TRACE
  	trace_create_file("tracing_max_latency", 0644, d_tracer,
  			&tracing_max_latency, &tracing_max_lat_fops);
  #endif
  
  	trace_create_file("tracing_thresh", 0644, d_tracer,
  			&tracing_thresh, &tracing_max_lat_fops);
  
  	trace_create_file("README", 0444, d_tracer,
  			NULL, &tracing_readme_fops);
  
  	trace_create_file("trace_pipe", 0444, d_tracer,
  			(void *) TRACE_PIPE_ALL_CPU, &tracing_pipe_fops);
  
  	trace_create_file("buffer_size_kb", 0644, d_tracer,
  			&global_trace, &tracing_entries_fops);
  
  	trace_create_file("trace_marker", 0220, d_tracer,
  			NULL, &tracing_mark_fops);
  
  	trace_create_file("saved_cmdlines", 0444, d_tracer,
  			NULL, &tracing_saved_cmdlines_fops);
  
  	trace_create_file("trace_clock", 0644, d_tracer, NULL,
  			  &trace_clock_fops);
  
  #ifdef CONFIG_DYNAMIC_FTRACE
  	trace_create_file("dyn_ftrace_total_info", 0444, d_tracer,
  			&ftrace_update_tot_cnt, &tracing_dyn_info_fops);
  #endif
  #ifdef CONFIG_SYSPROF_TRACER
  	init_tracer_sysprof_debugfs(d_tracer);
  #endif
  
  	create_trace_options_dir();
  
  	for_each_tracing_cpu(cpu)
  		tracing_init_debugfs_percpu(cpu);
  
  	return 0;
  }
  
  static int trace_panic_handler(struct notifier_block *this,
  			       unsigned long event, void *unused)
  {
  	if (ftrace_dump_on_oops)
  		ftrace_dump();
  	return NOTIFY_OK;
  }
  
  static struct notifier_block trace_panic_notifier = {
  	.notifier_call  = trace_panic_handler,
  	.next           = NULL,
  	.priority       = 150   /* priority: INT_MAX >= x >= 0 */
  };
  
  static int trace_die_handler(struct notifier_block *self,
  			     unsigned long val,
  			     void *data)
  {
  	switch (val) {
  	case DIE_OOPS:
  		if (ftrace_dump_on_oops)
  			ftrace_dump();
  		break;
  	default:
  		break;
  	}
  	return NOTIFY_OK;
  }
  
  static struct notifier_block trace_die_notifier = {
  	.notifier_call = trace_die_handler,
  	.priority = 200
  };
  
  /*
   * printk is set to max of 1024, we really don't need it that big.
   * Nothing should be printing 1000 characters anyway.
   */
  #define TRACE_MAX_PRINT		1000
  
  /*
   * Define here KERN_TRACE so that we have one place to modify
   * it if we decide to change what log level the ftrace dump
   * should be at.
   */
  #define KERN_TRACE		KERN_EMERG
  
  static void
  trace_printk_seq(struct trace_seq *s)
  {
  	/* Probably should print a warning here. */
  	if (s->len >= 1000)
  		s->len = 1000;
  
  	/* should be zero ended, but we are paranoid. */
  	s->buffer[s->len] = 0;
  
  	printk(KERN_TRACE "%s", s->buffer);
  
  	trace_seq_init(s);
  }
  
  static void __ftrace_dump(bool disable_tracing)
  {
  	static arch_spinlock_t ftrace_dump_lock =
  		(arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
  	/* use static because iter can be a bit big for the stack */
  	static struct trace_iterator iter;
  	unsigned int old_userobj;
  	static int dump_ran;
  	unsigned long flags;
  	int cnt = 0, cpu;
  
  	/* only one dump */
  	local_irq_save(flags);
  	arch_spin_lock(&ftrace_dump_lock);
  	if (dump_ran)
  		goto out;
  
  	dump_ran = 1;
  
  	tracing_off();
  
  	if (disable_tracing)
  		ftrace_kill();
  
  	for_each_tracing_cpu(cpu) {
  		atomic_inc(&global_trace.data[cpu]->disabled);
  	}
  
  	old_userobj = trace_flags & TRACE_ITER_SYM_USEROBJ;
  
  	/* don't look at user memory in panic mode */
  	trace_flags &= ~TRACE_ITER_SYM_USEROBJ;
  
  	printk(KERN_TRACE "Dumping ftrace buffer:\n");
  
  	/* Simulate the iterator */
  	iter.tr = &global_trace;
  	iter.trace = current_trace;
  	iter.cpu_file = TRACE_PIPE_ALL_CPU;
  
  	/*
  	 * We need to stop all tracing on all CPUS to read the
  	 * the next buffer. This is a bit expensive, but is
  	 * not done often. We fill all what we can read,
  	 * and then release the locks again.
  	 */
  
  	while (!trace_empty(&iter)) {
  
  		if (!cnt)
  			printk(KERN_TRACE "---------------------------------\n");
  
  		cnt++;
  
  		/* reset all but tr, trace, and overruns */
  		memset(&iter.seq, 0,
  		       sizeof(struct trace_iterator) -
  		       offsetof(struct trace_iterator, seq));
  		iter.iter_flags |= TRACE_FILE_LAT_FMT;
  		iter.pos = -1;
  
  		if (find_next_entry_inc(&iter) != NULL) {
  			int ret;
  
  			ret = print_trace_line(&iter);
  			if (ret != TRACE_TYPE_NO_CONSUME)
  				trace_consume(&iter);
  		}
  
  		trace_printk_seq(&iter.seq);
  	}
  
  	if (!cnt)
  		printk(KERN_TRACE "   (ftrace buffer empty)\n");
  	else
  		printk(KERN_TRACE "---------------------------------\n");
  
  	/* Re-enable tracing if requested */
  	if (!disable_tracing) {
  		trace_flags |= old_userobj;
  
  		for_each_tracing_cpu(cpu) {
  			atomic_dec(&global_trace.data[cpu]->disabled);
  		}
  		tracing_on();
  	}
  
   out:
  	arch_spin_unlock(&ftrace_dump_lock);
  	local_irq_restore(flags);
  }
  
  /* By default: disable tracing after the dump */
  void ftrace_dump(void)
  {
  	__ftrace_dump(true);
  }
  
  __init static int tracer_alloc_buffers(void)
  {
  	int ring_buf_size;
  	int i;
  	int ret = -ENOMEM;
  
  	if (!alloc_cpumask_var(&tracing_buffer_mask, GFP_KERNEL))
  		goto out;
  
  	if (!alloc_cpumask_var(&tracing_cpumask, GFP_KERNEL))
  		goto out_free_buffer_mask;
  
  	/* To save memory, keep the ring buffer size to its minimum */
  	if (ring_buffer_expanded)
  		ring_buf_size = trace_buf_size;
  	else
  		ring_buf_size = 1;
  
  	cpumask_copy(tracing_buffer_mask, cpu_possible_mask);
  	cpumask_copy(tracing_cpumask, cpu_all_mask);
  
  	/* TODO: make the number of buffers hot pluggable with CPUS */
  	global_trace.buffer = ring_buffer_alloc(ring_buf_size,
  						   TRACE_BUFFER_FLAGS);
  	if (!global_trace.buffer) {
  		printk(KERN_ERR "tracer: failed to allocate ring buffer!\n");
  		WARN_ON(1);
  		goto out_free_cpumask;
  	}
  	global_trace.entries = ring_buffer_size(global_trace.buffer);
  
  
  #ifdef CONFIG_TRACER_MAX_TRACE
  	max_tr.buffer = ring_buffer_alloc(ring_buf_size,
  					     TRACE_BUFFER_FLAGS);
  	if (!max_tr.buffer) {
  		printk(KERN_ERR "tracer: failed to allocate max ring buffer!\n");
  		WARN_ON(1);
  		ring_buffer_free(global_trace.buffer);
  		goto out_free_cpumask;
  	}
  	max_tr.entries = ring_buffer_size(max_tr.buffer);
  	WARN_ON(max_tr.entries != global_trace.entries);
  #endif
  
  	/* Allocate the first page for all buffers */
  	for_each_tracing_cpu(i) {
  		global_trace.data[i] = &per_cpu(global_trace_cpu, i);
  		max_tr.data[i] = &per_cpu(max_tr_data, i);
  	}
  
  	trace_init_cmdlines();
  
  	register_tracer(&nop_trace);
  	current_trace = &nop_trace;
  #ifdef CONFIG_BOOT_TRACER
  	register_tracer(&boot_tracer);
  #endif
  	/* All seems OK, enable tracing */
  	tracing_disabled = 0;
  
  	atomic_notifier_chain_register(&panic_notifier_list,
  				       &trace_panic_notifier);
  
  	register_die_notifier(&trace_die_notifier);
  
  	return 0;
  
  out_free_cpumask:
  	free_cpumask_var(tracing_cpumask);
  out_free_buffer_mask:
  	free_cpumask_var(tracing_buffer_mask);
  out:
  	return ret;
  }
  
  __init static int clear_boot_tracer(void)
  {
  	/*
  	 * The default tracer at boot buffer is an init section.
  	 * This function is called in lateinit. If we did not
  	 * find the boot tracer, then clear it out, to prevent
  	 * later registration from accessing the buffer that is
  	 * about to be freed.
  	 */
  	if (!default_bootup_tracer)
  		return 0;
  
  	printk(KERN_INFO "ftrace bootup tracer '%s' not registered.\n",
  	       default_bootup_tracer);
  	default_bootup_tracer = NULL;
  
  	return 0;
  }
  
  early_initcall(tracer_alloc_buffers);
  fs_initcall(tracer_init_debugfs);
  late_initcall(clear_boot_tracer);
  