text: /*
   *  linux/fs/proc/base.c
   *
   *  Copyright (C) 1991, 1992 Linus Torvalds
   *
   *  proc base directory handling functions
   *
   *  1999, Al Viro. Rewritten. Now it covers the whole per-process part.
   *  Instead of using magical inumbers to determine the kind of object
   *  we allocate and fill in-core inodes upon lookup. They don't even
   *  go into icache. We cache the reference to task_struct upon lookup too.
   *  Eventually it should become a filesystem in its own. We don't use the
   *  rest of procfs anymore.
   *
   *
   *  Changelog:
   *  17-Jan-2005
   *  Allan Bezerra
   *  Bruna Moreira <bruna.moreira@indt.org.br>
   *  Edjard Mota <edjard.mota@indt.org.br>
   *  Ilias Biris <ilias.biris@indt.org.br>
   *  Mauricio Lin <mauricio.lin@indt.org.br>
   *
   *  Embedded Linux Lab - 10LE Instituto Nokia de Tecnologia - INdT
   *
   *  A new process specific entry (smaps) included in /proc. It shows the
   *  size of rss for each memory area. The maps entry lacks information
   *  about physical memory size (rss) for each mapped file, i.e.,
   *  rss information for executables and library files.
   *  This additional information is useful for any tools that need to know
   *  about physical memory consumption for a process specific library.
   *
   *  Changelog:
   *  21-Feb-2005
   *  Embedded Linux Lab - 10LE Instituto Nokia de Tecnologia - INdT
   *  Pud inclusion in the page table walking.
   *
   *  ChangeLog:
   *  10-Mar-2005
   *  10LE Instituto Nokia de Tecnologia - INdT:
   *  A better way to walks through the page table as suggested by Hugh Dickins.
   *
   *  Simo Piiroinen <simo.piiroinen@nokia.com>:
   *  Smaps information related to shared, private, clean and dirty pages.
   *
   *  Paul Mundt <paul.mundt@nokia.com>:
   *  Overall revision about smaps.
   */
  
  #include <asm/uaccess.h>
  
  #include <linux/errno.h>
  #include <linux/time.h>
  #include <linux/proc_fs.h>
  #include <linux/stat.h>
  #include <linux/task_io_accounting_ops.h>
  #include <linux/init.h>
  #include <linux/capability.h>
  #include <linux/file.h>
  #include <linux/fdtable.h>
  #include <linux/string.h>
  #include <linux/seq_file.h>
  #include <linux/namei.h>
  #include <linux/mnt_namespace.h>
  #include <linux/mm.h>
  #include <linux/swap.h>
  #include <linux/rcupdate.h>
  #include <linux/kallsyms.h>
  #include <linux/stacktrace.h>
  #include <linux/resource.h>
  #include <linux/module.h>
  #include <linux/mount.h>
  #include <linux/security.h>
  #include <linux/ptrace.h>
  #include <linux/tracehook.h>
  #include <linux/cgroup.h>
  #include <linux/cpuset.h>
  #include <linux/audit.h>
  #include <linux/poll.h>
  #include <linux/nsproxy.h>
  #include <linux/oom.h>
  #include <linux/elf.h>
  #include <linux/pid_namespace.h>
  #include <linux/fs_struct.h>
  #include <linux/slab.h>
  #ifdef CONFIG_HARDWALL
  #include <asm/hardwall.h>
  #endif
  #include "internal.h"
  
  /* NOTE:
   *	Implementing inode permission operations in /proc is almost
   *	certainly an error.  Permission checks need to happen during
   *	each system call not at open time.  The reason is that most of
   *	what we wish to check for permissions in /proc varies at runtime.
   *
   *	The classic example of a problem is opening file descriptors
   *	in /proc for a task before it execs a suid executable.
   */
  
  struct pid_entry {
  	char *name;
  	int len;
  	mode_t mode;
  	const struct inode_operations *iop;
  	const struct file_operations *fop;
  	union proc_op op;
  };
  
  #define NOD(NAME, MODE, IOP, FOP, OP) {			\
  	.name = (NAME),					\
  	.len  = sizeof(NAME) - 1,			\
  	.mode = MODE,					\
  	.iop  = IOP,					\
  	.fop  = FOP,					\
  	.op   = OP,					\
  }
  
  #define DIR(NAME, MODE, iops, fops)	\
  	NOD(NAME, (S_IFDIR|(MODE)), &iops, &fops, {} )
  #define LNK(NAME, get_link)					\
  	NOD(NAME, (S_IFLNK|S_IRWXUGO),				\
  		&proc_pid_link_inode_operations, NULL,		\
  		{ .proc_get_link = get_link } )
  #define REG(NAME, MODE, fops)				\
  	NOD(NAME, (S_IFREG|(MODE)), NULL, &fops, {})
  #define INF(NAME, MODE, read)				\
  	NOD(NAME, (S_IFREG|(MODE)), 			\
  		NULL, &proc_info_file_operations,	\
  		{ .proc_read = read } )
  #define ONE(NAME, MODE, show)				\
  	NOD(NAME, (S_IFREG|(MODE)), 			\
  		NULL, &proc_single_file_operations,	\
  		{ .proc_show = show } )
  
  /* ANDROID is for special files in /proc. */
  #define ANDROID(NAME, MODE, OTYPE)			\
  	NOD(NAME, (S_IFREG|(MODE)),			\
  		&proc_##OTYPE##_inode_operations,	\
  		&proc_##OTYPE##_operations, {})
  
  /*
   * Count the number of hardlinks for the pid_entry table, excluding the .
   * and .. links.
   */
  static unsigned int pid_entry_count_dirs(const struct pid_entry *entries,
  	unsigned int n)
  {
  	unsigned int i;
  	unsigned int count;
  
  	count = 0;
  	for (i = 0; i < n; ++i) {
  		if (S_ISDIR(entries[i].mode))
  			++count;
  	}
  
  	return count;
  }
  
  static int get_task_root(struct task_struct *task, struct path *root)
  {
  	int result = -ENOENT;
  
  	task_lock(task);
  	if (task->fs) {
  		get_fs_root(task->fs, root);
  		result = 0;
  	}
  	task_unlock(task);
  	return result;
  }
  
  static int proc_cwd_link(struct inode *inode, struct path *path)
  {
  	struct task_struct *task = get_proc_task(inode);
  	int result = -ENOENT;
  
  	if (task) {
  		task_lock(task);
  		if (task->fs) {
  			get_fs_pwd(task->fs, path);
  			result = 0;
  		}
  		task_unlock(task);
  		put_task_struct(task);
  	}
  	return result;
  }
  
  static int proc_root_link(struct inode *inode, struct path *path)
  {
  	struct task_struct *task = get_proc_task(inode);
  	int result = -ENOENT;
  
  	if (task) {
  		result = get_task_root(task, path);
  		put_task_struct(task);
  	}
  	return result;
  }
  
  static struct mm_struct *mm_access(struct task_struct *task, unsigned int mode)
  {
  	struct mm_struct *mm;
  	int err;
  
  	err =  mutex_lock_killable(&task->signal->cred_guard_mutex);
  	if (err)
  		return ERR_PTR(err);
  
  	mm = get_task_mm(task);
  	if (mm && mm != current->mm &&
  			!ptrace_may_access(task, mode) &&
  			!capable(CAP_SYS_RESOURCE)) {
  		mmput(mm);
  		mm = ERR_PTR(-EACCES);
  	}
  	mutex_unlock(&task->signal->cred_guard_mutex);
  
  	return mm;
  }
  
  struct mm_struct *mm_for_maps(struct task_struct *task)
  {
  	return mm_access(task, PTRACE_MODE_READ);
  }
  
  static int proc_pid_cmdline(struct task_struct *task, char * buffer)
  {
  	int res = 0;
  	unsigned int len;
  	struct mm_struct *mm = get_task_mm(task);
  	if (!mm)
  		goto out;
  	if (!mm->arg_end)
  		goto out_mm;	/* Shh! No looking before we're done */
  
   	len = mm->arg_end - mm->arg_start;
  
  	if (len > PAGE_SIZE)
  		len = PAGE_SIZE;
  
  	res = access_process_vm(task, mm->arg_start, buffer, len, 0);
  
  	// If the nul at the end of args has been overwritten, then
  	// assume application is using setproctitle(3).
  	if (res > 0 && buffer[res-1] != '\0' && len < PAGE_SIZE) {
  		len = strnlen(buffer, res);
  		if (len < res) {
  		    res = len;
  		} else {
  			len = mm->env_end - mm->env_start;
  			if (len > PAGE_SIZE - res)
  				len = PAGE_SIZE - res;
  			res += access_process_vm(task, mm->env_start, buffer+res, len, 0);
  			res = strnlen(buffer, res);
  		}
  	}
  out_mm:
  	mmput(mm);
  out:
  	return res;
  }
  
  static int proc_pid_auxv(struct task_struct *task, char *buffer)
  {
  	struct mm_struct *mm = mm_for_maps(task);
  	int res = PTR_ERR(mm);
  	if (mm && !IS_ERR(mm)) {
  		unsigned int nwords = 0;
  		do {
  			nwords += 2;
  		} while (mm->saved_auxv[nwords - 2] != 0); /* AT_NULL */
  		res = nwords * sizeof(mm->saved_auxv[0]);
  		if (res > PAGE_SIZE)
  			res = PAGE_SIZE;
  		memcpy(buffer, mm->saved_auxv, res);
  		mmput(mm);
  	}
  	return res;
  }
  
  #ifdef CONFIG_KALLSYMS
  /*
   * Provides a wchan file via kallsyms in a proper one-value-per-file format.
   * Returns the resolved symbol.  If that fails, simply return the address.
   */
  static int proc_pid_wchan(struct task_struct *task, char *buffer)
  {
  	unsigned long wchan;
  	char symname[KSYM_NAME_LEN];
  
  	wchan = get_wchan(task);
  
  	if (lookup_symbol_name(wchan, symname) < 0)
  		if (!ptrace_may_access(task, PTRACE_MODE_READ))
  			return 0;
  		else
  			return sprintf(buffer, "%lu", wchan);
  	else
  		return sprintf(buffer, "%s", symname);
  }
  #endif /* CONFIG_KALLSYMS */
  
  static int lock_trace(struct task_struct *task)
  {
  	int err = mutex_lock_killable(&task->signal->cred_guard_mutex);
  	if (err)
  		return err;
  	if (!ptrace_may_access(task, PTRACE_MODE_ATTACH)) {
  		mutex_unlock(&task->signal->cred_guard_mutex);
  		return -EPERM;
  	}
  	return 0;
  }
  
  static void unlock_trace(struct task_struct *task)
  {
  	mutex_unlock(&task->signal->cred_guard_mutex);
  }
  
  #ifdef CONFIG_STACKTRACE
  
  #define MAX_STACK_TRACE_DEPTH	64
  
  static int proc_pid_stack(struct seq_file *m, struct pid_namespace *ns,
  			  struct pid *pid, struct task_struct *task)
  {
  	struct stack_trace trace;
  	unsigned long *entries;
  	int err;
  	int i;
  
  	entries = kmalloc(MAX_STACK_TRACE_DEPTH * sizeof(*entries), GFP_KERNEL);
  	if (!entries)
  		return -ENOMEM;
  
  	trace.nr_entries	= 0;
  	trace.max_entries	= MAX_STACK_TRACE_DEPTH;
  	trace.entries		= entries;
  	trace.skip		= 0;
  
  	err = lock_trace(task);
  	if (!err) {
  		save_stack_trace_tsk(task, &trace);
  
  		for (i = 0; i < trace.nr_entries; i++) {
  			seq_printf(m, "[<%pK>] %pS\n",
  				   (void *)entries[i], (void *)entries[i]);
  		}
  		unlock_trace(task);
  	}
  	kfree(entries);
  
  	return err;
  }
  #endif
  
  #ifdef CONFIG_SCHEDSTATS
  /*
   * Provides /proc/PID/schedstat
   */
  static int proc_pid_schedstat(struct task_struct *task, char *buffer)
  {
  	return sprintf(buffer, "%llu %llu %lu\n",
  			(unsigned long long)task->se.sum_exec_runtime,
  			(unsigned long long)task->sched_info.run_delay,
  			task->sched_info.pcount);
  }
  #endif
  
  #ifdef CONFIG_LATENCYTOP
  static int lstats_show_proc(struct seq_file *m, void *v)
  {
  	int i;
  	struct inode *inode = m->private;
  	struct task_struct *task = get_proc_task(inode);
  
  	if (!task)
  		return -ESRCH;
  	seq_puts(m, "Latency Top version : v0.1\n");
  	for (i = 0; i < 32; i++) {
  		struct latency_record *lr = &task->latency_record[i];
  		if (lr->backtrace[0]) {
  			int q;
  			seq_printf(m, "%i %li %li",
  				   lr->count, lr->time, lr->max);
  			for (q = 0; q < LT_BACKTRACEDEPTH; q++) {
  				unsigned long bt = lr->backtrace[q];
  				if (!bt)
  					break;
  				if (bt == ULONG_MAX)
  					break;
  				seq_printf(m, " %ps", (void *)bt);
  			}
  			seq_putc(m, '\n');
  		}
  
  	}
  	put_task_struct(task);
  	return 0;
  }
  
  static int lstats_open(struct inode *inode, struct file *file)
  {
  	return single_open(file, lstats_show_proc, inode);
  }
  
  static ssize_t lstats_write(struct file *file, const char __user *buf,
  			    size_t count, loff_t *offs)
  {
  	struct task_struct *task = get_proc_task(file->f_dentry->d_inode);
  
  	if (!task)
  		return -ESRCH;
  	clear_all_latency_tracing(task);
  	put_task_struct(task);
  
  	return count;
  }
  
  static const struct file_operations proc_lstats_operations = {
  	.open		= lstats_open,
  	.read		= seq_read,
  	.write		= lstats_write,
  	.llseek		= seq_lseek,
  	.release	= single_release,
  };
  
  #endif
  
  static int proc_oom_score(struct task_struct *task, char *buffer)
  {
  	unsigned long points = 0;
  
  	read_lock(&tasklist_lock);
  	if (pid_alive(task))
  		points = oom_badness(task, NULL, NULL,
  					totalram_pages + total_swap_pages);
  	read_unlock(&tasklist_lock);
  	return sprintf(buffer, "%lu\n", points);
  }
  
  struct limit_names {
  	char *name;
  	char *unit;
  };
  
  static const struct limit_names lnames[RLIM_NLIMITS] = {
  	[RLIMIT_CPU] = {"Max cpu time", "seconds"},
  	[RLIMIT_FSIZE] = {"Max file size", "bytes"},
  	[RLIMIT_DATA] = {"Max data size", "bytes"},
  	[RLIMIT_STACK] = {"Max stack size", "bytes"},
  	[RLIMIT_CORE] = {"Max core file size", "bytes"},
  	[RLIMIT_RSS] = {"Max resident set", "bytes"},
  	[RLIMIT_NPROC] = {"Max processes", "processes"},
  	[RLIMIT_NOFILE] = {"Max open files", "files"},
  	[RLIMIT_MEMLOCK] = {"Max locked memory", "bytes"},
  	[RLIMIT_AS] = {"Max address space", "bytes"},
  	[RLIMIT_LOCKS] = {"Max file locks", "locks"},
  	[RLIMIT_SIGPENDING] = {"Max pending signals", "signals"},
  	[RLIMIT_MSGQUEUE] = {"Max msgqueue size", "bytes"},
  	[RLIMIT_NICE] = {"Max nice priority", NULL},
  	[RLIMIT_RTPRIO] = {"Max realtime priority", NULL},
  	[RLIMIT_RTTIME] = {"Max realtime timeout", "us"},
  };
  
  /* Display limits for a process */
  static int proc_pid_limits(struct task_struct *task, char *buffer)
  {
  	unsigned int i;
  	int count = 0;
  	unsigned long flags;
  	char *bufptr = buffer;
  
  	struct rlimit rlim[RLIM_NLIMITS];
  
  	if (!lock_task_sighand(task, &flags))
  		return 0;
  	memcpy(rlim, task->signal->rlim, sizeof(struct rlimit) * RLIM_NLIMITS);
  	unlock_task_sighand(task, &flags);
  
  	/*
  	 * print the file header
  	 */
  	count += sprintf(&bufptr[count], "%-25s %-20s %-20s %-10s\n",
  			"Limit", "Soft Limit", "Hard Limit", "Units");
  
  	for (i = 0; i < RLIM_NLIMITS; i++) {
  		if (rlim[i].rlim_cur == RLIM_INFINITY)
  			count += sprintf(&bufptr[count], "%-25s %-20s ",
  					 lnames[i].name, "unlimited");
  		else
  			count += sprintf(&bufptr[count], "%-25s %-20lu ",
  					 lnames[i].name, rlim[i].rlim_cur);
  
  		if (rlim[i].rlim_max == RLIM_INFINITY)
  			count += sprintf(&bufptr[count], "%-20s ", "unlimited");
  		else
  			count += sprintf(&bufptr[count], "%-20lu ",
  					 rlim[i].rlim_max);
  
  		if (lnames[i].unit)
  			count += sprintf(&bufptr[count], "%-10s\n",
  					 lnames[i].unit);
  		else
  			count += sprintf(&bufptr[count], "\n");
  	}
  
  	return count;
  }
  
  #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
  static int proc_pid_syscall(struct task_struct *task, char *buffer)
  {
  	long nr;
  	unsigned long args[6], sp, pc;
  	int res = lock_trace(task);
  	if (res)
  		return res;
  
  	if (task_current_syscall(task, &nr, args, 6, &sp, &pc))
  		res = sprintf(buffer, "running\n");
  	else if (nr < 0)
  		res = sprintf(buffer, "%ld 0x%lx 0x%lx\n", nr, sp, pc);
  	else
  		res = sprintf(buffer,
  		       "%ld 0x%lx 0x%lx 0x%lx 0x%lx 0x%lx 0x%lx 0x%lx 0x%lx\n",
  		       nr,
  		       args[0], args[1], args[2], args[3], args[4], args[5],
  		       sp, pc);
  	unlock_trace(task);
  	return res;
  }
  #endif /* CONFIG_HAVE_ARCH_TRACEHOOK */
  
  /************************************************************************/
  /*                       Here the fs part begins                        */
  /************************************************************************/
  
  /* permission checks */
  static int proc_fd_access_allowed(struct inode *inode)
  {
  	struct task_struct *task;
  	int allowed = 0;
  	/* Allow access to a task's file descriptors if it is us or we
  	 * may use ptrace attach to the process and find out that
  	 * information.
  	 */
  	task = get_proc_task(inode);
  	if (task) {
  		allowed = ptrace_may_access(task, PTRACE_MODE_READ);
  		put_task_struct(task);
  	}
  	return allowed;
  }
  
  int proc_setattr(struct dentry *dentry, struct iattr *attr)
  {
  	int error;
  	struct inode *inode = dentry->d_inode;
  
  	if (attr->ia_valid & ATTR_MODE)
  		return -EPERM;
  
  	error = inode_change_ok(inode, attr);
  	if (error)
  		return error;
  
  	if ((attr->ia_valid & ATTR_SIZE) &&
  	    attr->ia_size != i_size_read(inode)) {
  		error = vmtruncate(inode, attr->ia_size);
  		if (error)
  			return error;
  	}
  
  	setattr_copy(inode, attr);
  	mark_inode_dirty(inode);
  	return 0;
  }
  
  static const struct inode_operations proc_def_inode_operations = {
  	.setattr	= proc_setattr,
  };
  
  static int mounts_open_common(struct inode *inode, struct file *file,
  			      const struct seq_operations *op)
  {
  	struct task_struct *task = get_proc_task(inode);
  	struct nsproxy *nsp;
  	struct mnt_namespace *ns = NULL;
  	struct path root;
  	struct proc_mounts *p;
  	int ret = -EINVAL;
  
  	if (task) {
  		rcu_read_lock();
  		nsp = task_nsproxy(task);
  		if (nsp) {
  			ns = nsp->mnt_ns;
  			if (ns)
  				get_mnt_ns(ns);
  		}
  		rcu_read_unlock();
  		if (ns && get_task_root(task, &root) == 0)
  			ret = 0;
  		put_task_struct(task);
  	}
  
  	if (!ns)
  		goto err;
  	if (ret)
  		goto err_put_ns;
  
  	ret = -ENOMEM;
  	p = kmalloc(sizeof(struct proc_mounts), GFP_KERNEL);
  	if (!p)
  		goto err_put_path;
  
  	file->private_data = &p->m;
  	ret = seq_open(file, op);
  	if (ret)
  		goto err_free;
  
  	p->m.private = p;
  	p->ns = ns;
  	p->root = root;
  	p->event = ns->event;
  
  	return 0;
  
   err_free:
  	kfree(p);
   err_put_path:
  	path_put(&root);
   err_put_ns:
  	put_mnt_ns(ns);
   err:
  	return ret;
  }
  
  static int mounts_release(struct inode *inode, struct file *file)
  {
  	struct proc_mounts *p = file->private_data;
  	path_put(&p->root);
  	put_mnt_ns(p->ns);
  	return seq_release(inode, file);
  }
  
  static unsigned mounts_poll(struct file *file, poll_table *wait)
  {
  	struct proc_mounts *p = file->private_data;
  	unsigned res = POLLIN | POLLRDNORM;
  
  	poll_wait(file, &p->ns->poll, wait);
  	if (mnt_had_events(p))
  		res |= POLLERR | POLLPRI;
  
  	return res;
  }
  
  static int mounts_open(struct inode *inode, struct file *file)
  {
  	return mounts_open_common(inode, file, &mounts_op);
  }
  
  static const struct file_operations proc_mounts_operations = {
  	.open		= mounts_open,
  	.read		= seq_read,
  	.llseek		= seq_lseek,
  	.release	= mounts_release,
  	.poll		= mounts_poll,
  };
  
  static int mountinfo_open(struct inode *inode, struct file *file)
  {
  	return mounts_open_common(inode, file, &mountinfo_op);
  }
  
  static const struct file_operations proc_mountinfo_operations = {
  	.open		= mountinfo_open,
  	.read		= seq_read,
  	.llseek		= seq_lseek,
  	.release	= mounts_release,
  	.poll		= mounts_poll,
  };
  
  static int mountstats_open(struct inode *inode, struct file *file)
  {
  	return mounts_open_common(inode, file, &mountstats_op);
  }
  
  static const struct file_operations proc_mountstats_operations = {
  	.open		= mountstats_open,
  	.read		= seq_read,
  	.llseek		= seq_lseek,
  	.release	= mounts_release,
  };
  
  #define PROC_BLOCK_SIZE	(3*1024)		/* 4K page size but our output routines use some slack for overruns */
  
  static ssize_t proc_info_read(struct file * file, char __user * buf,
  			  size_t count, loff_t *ppos)
  {
  	struct inode * inode = file->f_path.dentry->d_inode;
  	unsigned long page;
  	ssize_t length;
  	struct task_struct *task = get_proc_task(inode);
  
  	length = -ESRCH;
  	if (!task)
  		goto out_no_task;
  
  	if (count > PROC_BLOCK_SIZE)
  		count = PROC_BLOCK_SIZE;
  
  	length = -ENOMEM;
  	if (!(page = __get_free_page(GFP_TEMPORARY)))
  		goto out;
  
  	length = PROC_I(inode)->op.proc_read(task, (char*)page);
  
  	if (length >= 0)
  		length = simple_read_from_buffer(buf, count, ppos, (char *)page, length);
  	free_page(page);
  out:
  	put_task_struct(task);
  out_no_task:
  	return length;
  }
  
  static const struct file_operations proc_info_file_operations = {
  	.read		= proc_info_read,
  	.llseek		= generic_file_llseek,
  };
  
  static int proc_single_show(struct seq_file *m, void *v)
  {
  	struct inode *inode = m->private;
  	struct pid_namespace *ns;
  	struct pid *pid;
  	struct task_struct *task;
  	int ret;
  
  	ns = inode->i_sb->s_fs_info;
  	pid = proc_pid(inode);
  	task = get_pid_task(pid, PIDTYPE_PID);
  	if (!task)
  		return -ESRCH;
  
  	ret = PROC_I(inode)->op.proc_show(m, ns, pid, task);
  
  	put_task_struct(task);
  	return ret;
  }
  
  static int proc_single_open(struct inode *inode, struct file *filp)
  {
  	return single_open(filp, proc_single_show, inode);
  }
  
  static const struct file_operations proc_single_file_operations = {
  	.open		= proc_single_open,
  	.read		= seq_read,
  	.llseek		= seq_lseek,
  	.release	= single_release,
  };
  
  static int mem_open(struct inode* inode, struct file* file)
  {
  	struct task_struct *task = get_proc_task(file->f_path.dentry->d_inode);
  	struct mm_struct *mm;
  
  	if (!task)
  		return -ESRCH;
  
  	mm = mm_access(task, PTRACE_MODE_ATTACH);
  	put_task_struct(task);
  
  	if (IS_ERR(mm))
  		return PTR_ERR(mm);
  
  	if (mm) {
  		/* ensure this mm_struct can't be freed */
  		atomic_inc(&mm->mm_count);
  		/* but do not pin its memory */
  		mmput(mm);
  	}
  
  	/* OK to pass negative loff_t, we can catch out-of-range */
  	file->f_mode |= FMODE_UNSIGNED_OFFSET;
  	file->private_data = mm;
  
  	return 0;
  }
  
  static ssize_t mem_rw(struct file *file, char __user *buf,
  			size_t count, loff_t *ppos, int write)
  {
  	struct mm_struct *mm = file->private_data;
  	unsigned long addr = *ppos;
  	ssize_t copied;
  	char *page;
  
  	if (!mm)
  		return 0;
  
  	page = (char *)__get_free_page(GFP_TEMPORARY);
  	if (!page)
  		return -ENOMEM;
  
  	copied = 0;
  	if (!atomic_inc_not_zero(&mm->mm_users))
  		goto free;
  
  	while (count > 0) {
  		int this_len = min_t(int, count, PAGE_SIZE);
  
  		if (write && copy_from_user(page, buf, this_len)) {
  			copied = -EFAULT;
  			break;
  		}
  
  		this_len = access_remote_vm(mm, addr, page, this_len, write);
  		if (!this_len) {
  			if (!copied)
  				copied = -EIO;
  			break;
  		}
  
  		if (!write && copy_to_user(buf, page, this_len)) {
  			copied = -EFAULT;
  			break;
  		}
  
  		buf += this_len;
  		addr += this_len;
  		copied += this_len;
  		count -= this_len;
  	}
  	*ppos = addr;
  
  	mmput(mm);
  free:
  	free_page((unsigned long) page);
  	return copied;
  }
  
  static ssize_t mem_read(struct file *file, char __user *buf,
  			size_t count, loff_t *ppos)
  {
  	return mem_rw(file, buf, count, ppos, 0);
  }
  
  #define mem_write NULL
  
  #ifndef mem_write
  /* This is a security hazard */
  static ssize_t mem_write(struct file *file, const char __user *buf,
  			 size_t count, loff_t *ppos)
  {
  	return mem_rw(file, (char __user*)buf, count, ppos, 1);
  }
  #endif
  
  loff_t mem_lseek(struct file *file, loff_t offset, int orig)
  {
  	switch (orig) {
  	case 0:
  		file->f_pos = offset;
  		break;
  	case 1:
  		file->f_pos += offset;
  		break;
  	default:
  		return -EINVAL;
  	}
  	force_successful_syscall_return();
  	return file->f_pos;
  }
  
  static int mem_release(struct inode *inode, struct file *file)
  {
  	struct mm_struct *mm = file->private_data;
  	if (mm)
  		mmdrop(mm);
  	return 0;
  }
  
  static const struct file_operations proc_mem_operations = {
  	.llseek		= mem_lseek,
  	.read		= mem_read,
  	.write		= mem_write,
  	.open		= mem_open,
  	.release	= mem_release,
  };
  
  static ssize_t environ_read(struct file *file, char __user *buf,
  			size_t count, loff_t *ppos)
  {
  	struct task_struct *task = get_proc_task(file->f_dentry->d_inode);
  	char *page;
  	unsigned long src = *ppos;
  	int ret = -ESRCH;
  	struct mm_struct *mm;
  
  	if (!task)
  		goto out_no_task;
  
  	ret = -ENOMEM;
  	page = (char *)__get_free_page(GFP_TEMPORARY);
  	if (!page)
  		goto out;
  
  	mm = mm_for_maps(task);
  	ret = PTR_ERR(mm);
  	if (!mm || IS_ERR(mm))
  		goto out_free;
  
  	ret = 0;
  	while (count > 0) {
  		int this_len, retval, max_len;
  
  		this_len = mm->env_end - (mm->env_start + src);
  
  		if (this_len <= 0)
  			break;
  
  		max_len = (count > PAGE_SIZE) ? PAGE_SIZE : count;
  		this_len = (this_len > max_len) ? max_len : this_len;
  
  		retval = access_process_vm(task, (mm->env_start + src),
  			page, this_len, 0);
  
  		if (retval <= 0) {
  			ret = retval;
  			break;
  		}
  
  		if (copy_to_user(buf, page, retval)) {
  			ret = -EFAULT;
  			break;
  		}
  
  		ret += retval;
  		src += retval;
  		buf += retval;
  		count -= retval;
  	}
  	*ppos = src;
  
  	mmput(mm);
  out_free:
  	free_page((unsigned long) page);
  out:
  	put_task_struct(task);
  out_no_task:
  	return ret;
  }
  
  static const struct file_operations proc_environ_operations = {
  	.read		= environ_read,
  	.llseek		= generic_file_llseek,
  };
  
  static ssize_t oom_adjust_read(struct file *file, char __user *buf,
  				size_t count, loff_t *ppos)
  {
  	struct task_struct *task = get_proc_task(file->f_path.dentry->d_inode);
  	char buffer[PROC_NUMBUF];
  	size_t len;
  	int oom_adjust = OOM_DISABLE;
  	unsigned long flags;
  
  	if (!task)
  		return -ESRCH;
  
  	if (lock_task_sighand(task, &flags)) {
  		oom_adjust = task->signal->oom_adj;
  		unlock_task_sighand(task, &flags);
  	}
  
  	put_task_struct(task);
  
  	len = snprintf(buffer, sizeof(buffer), "%i\n", oom_adjust);
  
  	return simple_read_from_buffer(buf, count, ppos, buffer, len);
  }
  
  static ssize_t oom_adjust_write(struct file *file, const char __user *buf,
  				size_t count, loff_t *ppos)
  {
  	struct task_struct *task;
  	char buffer[PROC_NUMBUF];
  	int oom_adjust;
  	unsigned long flags;
  	int err;
  
  	memset(buffer, 0, sizeof(buffer));
  	if (count > sizeof(buffer) - 1)
  		count = sizeof(buffer) - 1;
  	if (copy_from_user(buffer, buf, count)) {
  		err = -EFAULT;
  		goto out;
  	}
  
  	err = kstrtoint(strstrip(buffer), 0, &oom_adjust);
  	if (err)
  		goto out;
  	if ((oom_adjust < OOM_ADJUST_MIN || oom_adjust > OOM_ADJUST_MAX) &&
  	     oom_adjust != OOM_DISABLE) {
  		err = -EINVAL;
  		goto out;
  	}
  
  	task = get_proc_task(file->f_path.dentry->d_inode);
  	if (!task) {
  		err = -ESRCH;
  		goto out;
  	}
  
  	task_lock(task);
  	if (!task->mm) {
  		err = -EINVAL;
  		goto err_task_lock;
  	}
  
  	if (!lock_task_sighand(task, &flags)) {
  		err = -ESRCH;
  		goto err_task_lock;
  	}
  
  	if (oom_adjust < task->signal->oom_adj && !capable(CAP_SYS_RESOURCE)) {
  		err = -EACCES;
  		goto err_sighand;
  	}
  
  	if (oom_adjust != task->signal->oom_adj) {
  		if (oom_adjust == OOM_DISABLE)
  			atomic_inc(&task->mm->oom_disable_count);
  		if (task->signal->oom_adj == OOM_DISABLE)
  			atomic_dec(&task->mm->oom_disable_count);
  	}
  
  	/*
  	 * Warn that /proc/pid/oom_adj is deprecated, see
  	 * Documentation/feature-removal-schedule.txt.
  	 */
  	printk_once(KERN_WARNING "%s (%d): /proc/%d/oom_adj is deprecated, "
  			"please use /proc/%d/oom_score_adj instead.\n",
  			current->comm, task_pid_nr(current),
  			task_pid_nr(task), task_pid_nr(task));
  	task->signal->oom_adj = oom_adjust;
  	/*
  	 * Scale /proc/pid/oom_score_adj appropriately ensuring that a maximum
  	 * value is always attainable.
  	 */
  	if (task->signal->oom_adj == OOM_ADJUST_MAX)
  		task->signal->oom_score_adj = OOM_SCORE_ADJ_MAX;
  	else
  		task->signal->oom_score_adj = (oom_adjust * OOM_SCORE_ADJ_MAX) /
  								-OOM_DISABLE;
  err_sighand:
  	unlock_task_sighand(task, &flags);
  err_task_lock:
  	task_unlock(task);
  	put_task_struct(task);
  out:
  	return err < 0 ? err : count;
  }
  
  static int oom_adjust_permission(struct inode *inode, int mask,
  				 unsigned int flags)
  {
  	uid_t uid;
  	struct task_struct *p;
  
  	if (flags & IPERM_FLAG_RCU)
  		return -ECHILD;
  
  	p = get_proc_task(inode);
  	if(p) {
  		uid = task_uid(p);
  		put_task_struct(p);
  	}
  
  	/*
  	 * System Server (uid == 1000) is granted access to oom_adj of all
  	 * android applications (uid > 10000) as and services (uid >= 1000)
  	 */
  	if (p && (current_fsuid() == 1000) && (uid >= 1000)) {
  		if (inode->i_mode >> 6 & mask) {
  			return 0;
  		}
  	}
  
  	/* Fall back to default. */
  	return generic_permission(inode, mask, flags, NULL);
  }
  
  static const struct inode_operations proc_oom_adjust_inode_operations = {
  	.permission	= oom_adjust_permission,
  };
  
  static const struct file_operations proc_oom_adjust_operations = {
  	.read		= oom_adjust_read,
  	.write		= oom_adjust_write,
  	.llseek		= generic_file_llseek,
  };
  
  static ssize_t oom_score_adj_read(struct file *file, char __user *buf,
  					size_t count, loff_t *ppos)
  {
  	struct task_struct *task = get_proc_task(file->f_path.dentry->d_inode);
  	char buffer[PROC_NUMBUF];
  	int oom_score_adj = OOM_SCORE_ADJ_MIN;
  	unsigned long flags;
  	size_t len;
  
  	if (!task)
  		return -ESRCH;
  	if (lock_task_sighand(task, &flags)) {
  		oom_score_adj = task->signal->oom_score_adj;
  		unlock_task_sighand(task, &flags);
  	}
  	put_task_struct(task);
  	len = snprintf(buffer, sizeof(buffer), "%d\n", oom_score_adj);
  	return simple_read_from_buffer(buf, count, ppos, buffer, len);
  }
  
  static ssize_t oom_score_adj_write(struct file *file, const char __user *buf,
  					size_t count, loff_t *ppos)
  {
  	struct task_struct *task;
  	char buffer[PROC_NUMBUF];
  	unsigned long flags;
  	int oom_score_adj;
  	int err;
  
  	memset(buffer, 0, sizeof(buffer));
  	if (count > sizeof(buffer) - 1)
  		count = sizeof(buffer) - 1;
  	if (copy_from_user(buffer, buf, count)) {
  		err = -EFAULT;
  		goto out;
  	}
  
  	err = kstrtoint(strstrip(buffer), 0, &oom_score_adj);
  	if (err)
  		goto out;
  	if (oom_score_adj < OOM_SCORE_ADJ_MIN ||
  			oom_score_adj > OOM_SCORE_ADJ_MAX) {
  		err = -EINVAL;
  		goto out;
  	}
  
  	task = get_proc_task(file->f_path.dentry->d_inode);
  	if (!task) {
  		err = -ESRCH;
  		goto out;
  	}
  
  	task_lock(task);
  	if (!task->mm) {
  		err = -EINVAL;
  		goto err_task_lock;
  	}
  
  	if (!lock_task_sighand(task, &flags)) {
  		err = -ESRCH;
  		goto err_task_lock;
  	}
  
  	if (oom_score_adj < task->signal->oom_score_adj_min &&
  			!capable(CAP_SYS_RESOURCE)) {
  		err = -EACCES;
  		goto err_sighand;
  	}
  
  	if (oom_score_adj != task->signal->oom_score_adj) {
  		if (oom_score_adj == OOM_SCORE_ADJ_MIN)
  			atomic_inc(&task->mm->oom_disable_count);
  		if (task->signal->oom_score_adj == OOM_SCORE_ADJ_MIN)
  			atomic_dec(&task->mm->oom_disable_count);
  	}
  	task->signal->oom_score_adj = oom_score_adj;
  	if (has_capability_noaudit(current, CAP_SYS_RESOURCE))
  		task->signal->oom_score_adj_min = oom_score_adj;
  	/*
  	 * Scale /proc/pid/oom_adj appropriately ensuring that OOM_DISABLE is
  	 * always attainable.
  	 */
  	if (task->signal->oom_score_adj == OOM_SCORE_ADJ_MIN)
  		task->signal->oom_adj = OOM_DISABLE;
  	else
  		task->signal->oom_adj = (oom_score_adj * OOM_ADJUST_MAX) /
  							OOM_SCORE_ADJ_MAX;
  err_sighand:
  	unlock_task_sighand(task, &flags);
  err_task_lock:
  	task_unlock(task);
  	put_task_struct(task);
  out:
  	return err < 0 ? err : count;
  }
  
  static const struct file_operations proc_oom_score_adj_operations = {
  	.read		= oom_score_adj_read,
  	.write		= oom_score_adj_write,
  	.llseek		= default_llseek,
  };
  
  #ifdef CONFIG_AUDITSYSCALL
  #define TMPBUFLEN 21
  static ssize_t proc_loginuid_read(struct file * file, char __user * buf,
  				  size_t count, loff_t *ppos)
  {
  	struct inode * inode = file->f_path.dentry->d_inode;
  	struct task_struct *task = get_proc_task(inode);
  	ssize_t length;
  	char tmpbuf[TMPBUFLEN];
  
  	if (!task)
  		return -ESRCH;
  	length = scnprintf(tmpbuf, TMPBUFLEN, "%u",
  				audit_get_loginuid(task));
  	put_task_struct(task);
  	return simple_read_from_buffer(buf, count, ppos, tmpbuf, length);
  }
  
  static ssize_t proc_loginuid_write(struct file * file, const char __user * buf,
  				   size_t count, loff_t *ppos)
  {
  	struct inode * inode = file->f_path.dentry->d_inode;
  	char *page, *tmp;
  	ssize_t length;
  	uid_t loginuid;
  
  	if (!capable(CAP_AUDIT_CONTROL))
  		return -EPERM;
  
  	rcu_read_lock();
  	if (current != pid_task(proc_pid(inode), PIDTYPE_PID)) {
  		rcu_read_unlock();
  		return -EPERM;
  	}
  	rcu_read_unlock();
  
  	if (count >= PAGE_SIZE)
  		count = PAGE_SIZE - 1;
  
  	if (*ppos != 0) {
  		/* No partial writes. */
  		return -EINVAL;
  	}
  	page = (char*)__get_free_page(GFP_TEMPORARY);
  	if (!page)
  		return -ENOMEM;
  	length = -EFAULT;
  	if (copy_from_user(page, buf, count))
  		goto out_free_page;
  
  	page[count] = '\0';
  	loginuid = simple_strtoul(page, &tmp, 10);
  	if (tmp == page) {
  		length = -EINVAL;
  		goto out_free_page;
  
  	}
  	length = audit_set_loginuid(current, loginuid);
  	if (likely(length == 0))
  		length = count;
  
  out_free_page:
  	free_page((unsigned long) page);
  	return length;
  }
  
  static const struct file_operations proc_loginuid_operations = {
  	.read		= proc_loginuid_read,
  	.write		= proc_loginuid_write,
  	.llseek		= generic_file_llseek,
  };
  
  static ssize_t proc_sessionid_read(struct file * file, char __user * buf,
  				  size_t count, loff_t *ppos)
  {
  	struct inode * inode = file->f_path.dentry->d_inode;
  	struct task_struct *task = get_proc_task(inode);
  	ssize_t length;
  	char tmpbuf[TMPBUFLEN];
  
  	if (!task)
  		return -ESRCH;
  	length = scnprintf(tmpbuf, TMPBUFLEN, "%u",
  				audit_get_sessionid(task));
  	put_task_struct(task);
  	return simple_read_from_buffer(buf, count, ppos, tmpbuf, length);
  }
  
  static const struct file_operations proc_sessionid_operations = {
  	.read		= proc_sessionid_read,
  	.llseek		= generic_file_llseek,
  };
  #endif
  
  #ifdef CONFIG_FAULT_INJECTION
  static ssize_t proc_fault_inject_read(struct file * file, char __user * buf,
  				      size_t count, loff_t *ppos)
  {
  	struct task_struct *task = get_proc_task(file->f_dentry->d_inode);
  	char buffer[PROC_NUMBUF];
  	size_t len;
  	int make_it_fail;
  
  	if (!task)
  		return -ESRCH;
  	make_it_fail = task->make_it_fail;
  	put_task_struct(task);
  
  	len = snprintf(buffer, sizeof(buffer), "%i\n", make_it_fail);
  
  	return simple_read_from_buffer(buf, count, ppos, buffer, len);
  }
  
  static ssize_t proc_fault_inject_write(struct file * file,
  			const char __user * buf, size_t count, loff_t *ppos)
  {
  	struct task_struct *task;
  	char buffer[PROC_NUMBUF], *end;
  	int make_it_fail;
  
  	if (!capable(CAP_SYS_RESOURCE))
  		return -EPERM;
  	memset(buffer, 0, sizeof(buffer));
  	if (count > sizeof(buffer) - 1)
  		count = sizeof(buffer) - 1;
  	if (copy_from_user(buffer, buf, count))
  		return -EFAULT;
  	make_it_fail = simple_strtol(strstrip(buffer), &end, 0);
  	if (*end)
  		return -EINVAL;
  	task = get_proc_task(file->f_dentry->d_inode);
  	if (!task)
  		return -ESRCH;
  	task->make_it_fail = make_it_fail;
  	put_task_struct(task);
  
  	return count;
  }
  
  static const struct file_operations proc_fault_inject_operations = {
  	.read		= proc_fault_inject_read,
  	.write		= proc_fault_inject_write,
  	.llseek		= generic_file_llseek,
  };
  #endif
  
  #ifdef CONFIG_SCHED_DEBUG
  /*
   * Print out various scheduling related per-task fields:
   */
  static int sched_show(struct seq_file *m, void *v)
  {
  	struct inode *inode = m->private;
  	struct task_struct *p;
  
  	p = get_proc_task(inode);
  	if (!p)
  		return -ESRCH;
  	proc_sched_show_task(p, m);
  
  	put_task_struct(p);
  
  	return 0;
  }
  
  static ssize_t
  sched_write(struct file *file, const char __user *buf,
  	    size_t count, loff_t *offset)
  {
  	struct inode *inode = file->f_path.dentry->d_inode;
  	struct task_struct *p;
  
  	p = get_proc_task(inode);
  	if (!p)
  		return -ESRCH;
  	proc_sched_set_task(p);
  
  	put_task_struct(p);
  
  	return count;
  }
  
  static int sched_open(struct inode *inode, struct file *filp)
  {
  	return single_open(filp, sched_show, inode);
  }
  
  static const struct file_operations proc_pid_sched_operations = {
  	.open		= sched_open,
  	.read		= seq_read,
  	.write		= sched_write,
  	.llseek		= seq_lseek,
  	.release	= single_release,
  };
  
  #endif
  
  #ifdef CONFIG_SCHED_AUTOGROUP
  /*
   * Print out autogroup related information:
   */
  static int sched_autogroup_show(struct seq_file *m, void *v)
  {
  	struct inode *inode = m->private;
  	struct task_struct *p;
  
  	p = get_proc_task(inode);
  	if (!p)
  		return -ESRCH;
  	proc_sched_autogroup_show_task(p, m);
  
  	put_task_struct(p);
  
  	return 0;
  }
  
  static ssize_t
  sched_autogroup_write(struct file *file, const char __user *buf,
  	    size_t count, loff_t *offset)
  {
  	struct inode *inode = file->f_path.dentry->d_inode;
  	struct task_struct *p;
  	char buffer[PROC_NUMBUF];
  	int nice;
  	int err;
  
  	memset(buffer, 0, sizeof(buffer));
  	if (count > sizeof(buffer) - 1)
  		count = sizeof(buffer) - 1;
  	if (copy_from_user(buffer, buf, count))
  		return -EFAULT;
  
  	err = kstrtoint(strstrip(buffer), 0, &nice);
  	if (err < 0)
  		return err;
  
  	p = get_proc_task(inode);
  	if (!p)
  		return -ESRCH;
  
  	err = nice;
  	err = proc_sched_autogroup_set_nice(p, &err);
  	if (err)
  		count = err;
  
  	put_task_struct(p);
  
  	return count;
  }
  
  static int sched_autogroup_open(struct inode *inode, struct file *filp)
  {
  	int ret;
  
  	ret = single_open(filp, sched_autogroup_show, NULL);
  	if (!ret) {
  		struct seq_file *m = filp->private_data;
  
  		m->private = inode;
  	}
  	return ret;
  }
  
  static const struct file_operations proc_pid_sched_autogroup_operations = {
  	.open		= sched_autogroup_open,
  	.read		= seq_read,
  	.write		= sched_autogroup_write,
  	.llseek		= seq_lseek,
  	.release	= single_release,
  };
  
  #endif /* CONFIG_SCHED_AUTOGROUP */
  
  static ssize_t comm_write(struct file *file, const char __user *buf,
  				size_t count, loff_t *offset)
  {
  	struct inode *inode = file->f_path.dentry->d_inode;
  	struct task_struct *p;
  	char buffer[TASK_COMM_LEN];
  
  	memset(buffer, 0, sizeof(buffer));
  	if (count > sizeof(buffer) - 1)
  		count = sizeof(buffer) - 1;
  	if (copy_from_user(buffer, buf, count))
  		return -EFAULT;
  
  	p = get_proc_task(inode);
  	if (!p)
  		return -ESRCH;
  
  	if (same_thread_group(current, p))
  		set_task_comm(p, buffer);
  	else
  		count = -EINVAL;
  
  	put_task_struct(p);
  
  	return count;
  }
  
  static int comm_show(struct seq_file *m, void *v)
  {
  	struct inode *inode = m->private;
  	struct task_struct *p;
  
  	p = get_proc_task(inode);
  	if (!p)
  		return -ESRCH;
  
  	task_lock(p);
  	seq_printf(m, "%s\n", p->comm);
  	task_unlock(p);
  
  	put_task_struct(p);
  
  	return 0;
  }
  
  static int comm_open(struct inode *inode, struct file *filp)
  {
  	return single_open(filp, comm_show, inode);
  }
  
  static const struct file_operations proc_pid_set_comm_operations = {
  	.open		= comm_open,
  	.read		= seq_read,
  	.write		= comm_write,
  	.llseek		= seq_lseek,
  	.release	= single_release,
  };
  
  static int proc_exe_link(struct inode *inode, struct path *exe_path)
  {
  	struct task_struct *task;
  	struct mm_struct *mm;
  	struct file *exe_file;
  
  	task = get_proc_task(inode);
  	if (!task)
  		return -ENOENT;
  	mm = get_task_mm(task);
  	put_task_struct(task);
  	if (!mm)
  		return -ENOENT;
  	exe_file = get_mm_exe_file(mm);
  	mmput(mm);
  	if (exe_file) {
  		*exe_path = exe_file->f_path;
  		path_get(&exe_file->f_path);
  		fput(exe_file);
  		return 0;
  	} else
  		return -ENOENT;
  }
  
  static void *proc_pid_follow_link(struct dentry *dentry, struct nameidata *nd)
  {
  	struct inode *inode = dentry->d_inode;
  	int error = -EACCES;
  
  	/* We don't need a base pointer in the /proc filesystem */
  	path_put(&nd->path);
  
  	/* Are we allowed to snoop on the tasks file descriptors? */
  	if (!proc_fd_access_allowed(inode))
  		goto out;
  
  	error = PROC_I(inode)->op.proc_get_link(inode, &nd->path);
  out:
  	return ERR_PTR(error);
  }
  
  static int do_proc_readlink(struct path *path, char __user *buffer, int buflen)
  {
  	char *tmp = (char*)__get_free_page(GFP_TEMPORARY);
  	char *pathname;
  	int len;
  
  	if (!tmp)
  		return -ENOMEM;
  
  	pathname = d_path(path, tmp, PAGE_SIZE);
  	len = PTR_ERR(pathname);
  	if (IS_ERR(pathname))
  		goto out;
  	len = tmp + PAGE_SIZE - 1 - pathname;
  
  	if (len > buflen)
  		len = buflen;
  	if (copy_to_user(buffer, pathname, len))
  		len = -EFAULT;
   out:
  	free_page((unsigned long)tmp);
  	return len;
  }
  
  static int proc_pid_readlink(struct dentry * dentry, char __user * buffer, int buflen)
  {
  	int error = -EACCES;
  	struct inode *inode = dentry->d_inode;
  	struct path path;
  
  	/* Are we allowed to snoop on the tasks file descriptors? */
  	if (!proc_fd_access_allowed(inode))
  		goto out;
  
  	error = PROC_I(inode)->op.proc_get_link(inode, &path);
  	if (error)
  		goto out;
  
  	error = do_proc_readlink(&path, buffer, buflen);
  	path_put(&path);
  out:
  	return error;
  }
  
  static const struct inode_operations proc_pid_link_inode_operations = {
  	.readlink	= proc_pid_readlink,
  	.follow_link	= proc_pid_follow_link,
  	.setattr	= proc_setattr,
  };
  
  /* building an inode */
  
  static int task_dumpable(struct task_struct *task)
  {
  	int dumpable = 0;
  	struct mm_struct *mm;
  
  	task_lock(task);
  	mm = task->mm;
  	if (mm)
  		dumpable = get_dumpable(mm);
  	task_unlock(task);
  	if(dumpable == 1)
  		return 1;
  	return 0;
  }
  
  struct inode *proc_pid_make_inode(struct super_block * sb, struct task_struct *task)
  {
  	struct inode * inode;
  	struct proc_inode *ei;
  	const struct cred *cred;
  
  	/* We need a new inode */
  
  	inode = new_inode(sb);
  	if (!inode)
  		goto out;
  
  	/* Common stuff */
  	ei = PROC_I(inode);
  	inode->i_ino = get_next_ino();
  	inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
  	inode->i_op = &proc_def_inode_operations;
  
  	/*
  	 * grab the reference to task.
  	 */
  	ei->pid = get_task_pid(task, PIDTYPE_PID);
  	if (!ei->pid)
  		goto out_unlock;
  
  	if (task_dumpable(task)) {
  		rcu_read_lock();
  		cred = __task_cred(task);
  		inode->i_uid = cred->euid;
  		inode->i_gid = cred->egid;
  		rcu_read_unlock();
  	}
  	security_task_to_inode(task, inode);
  
  out:
  	return inode;
  
  out_unlock:
  	iput(inode);
  	return NULL;
  }
  
  int pid_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
  {
  	struct inode *inode = dentry->d_inode;
  	struct task_struct *task;
  	const struct cred *cred;
  
  	generic_fillattr(inode, stat);
  
  	rcu_read_lock();
  	stat->uid = 0;
  	stat->gid = 0;
  	task = pid_task(proc_pid(inode), PIDTYPE_PID);
  	if (task) {
  		if ((inode->i_mode == (S_IFDIR|S_IRUGO|S_IXUGO)) ||
  		    task_dumpable(task)) {
  			cred = __task_cred(task);
  			stat->uid = cred->euid;
  			stat->gid = cred->egid;
  		}
  	}
  	rcu_read_unlock();
  	return 0;
  }
  
  /* dentry stuff */
  
  /*
   *	Exceptional case: normally we are not allowed to unhash a busy
   * directory. In this case, however, we can do it - no aliasing problems
   * due to the way we treat inodes.
   *
   * Rewrite the inode's ownerships here because the owning task may have
   * performed a setuid(), etc.
   *
   * Before the /proc/pid/status file was created the only way to read
   * the effective uid of a /process was to stat /proc/pid.  Reading
   * /proc/pid/status is slow enough that procps and other packages
   * kept stating /proc/pid.  To keep the rules in /proc simple I have
   * made this apply to all per process world readable and executable
   * directories.
   */
  int pid_revalidate(struct dentry *dentry, struct nameidata *nd)
  {
  	struct inode *inode;
  	struct task_struct *task;
  	const struct cred *cred;
  
  	if (nd && nd->flags & LOOKUP_RCU)
  		return -ECHILD;
  
  	inode = dentry->d_inode;
  	task = get_proc_task(inode);
  
  	if (task) {
  		if ((inode->i_mode == (S_IFDIR|S_IRUGO|S_IXUGO)) ||
  		    task_dumpable(task)) {
  			rcu_read_lock();
  			cred = __task_cred(task);
  			inode->i_uid = cred->euid;
  			inode->i_gid = cred->egid;
  			rcu_read_unlock();
  		} else {
  			inode->i_uid = 0;
  			inode->i_gid = 0;
  		}
  		inode->i_mode &= ~(S_ISUID | S_ISGID);
  		security_task_to_inode(task, inode);
  		put_task_struct(task);
  		return 1;
  	}
  	d_drop(dentry);
  	return 0;
  }
  
  static int pid_delete_dentry(const struct dentry * dentry)
  {
  	/* Is the task we represent dead?
  	 * If so, then don't put the dentry on the lru list,
  	 * kill it immediately.
  	 */
  	return !proc_pid(dentry->d_inode)->tasks[PIDTYPE_PID].first;
  }
  
  const struct dentry_operations pid_dentry_operations =
  {
  	.d_revalidate	= pid_revalidate,
  	.d_delete	= pid_delete_dentry,
  };
  
  /* Lookups */
  
  /*
   * Fill a directory entry.
   *
   * If possible create the dcache entry and derive our inode number and
   * file type from dcache entry.
   *
   * Since all of the proc inode numbers are dynamically generated, the inode
   * numbers do not exist until the inode is cache.  This means creating the
   * the dcache entry in readdir is necessary to keep the inode numbers
   * reported by readdir in sync with the inode numbers reported
   * by stat.
   */
  int proc_fill_cache(struct file *filp, void *dirent, filldir_t filldir,
  	const char *name, int len,
  	instantiate_t instantiate, struct task_struct *task, const void *ptr)
  {
  	struct dentry *child, *dir = filp->f_path.dentry;
  	struct inode *inode;
  	struct qstr qname;
  	ino_t ino = 0;
  	unsigned type = DT_UNKNOWN;
  
  	qname.name = name;
  	qname.len  = len;
  	qname.hash = full_name_hash(name, len);
  
  	child = d_lookup(dir, &qname);
  	if (!child) {
  		struct dentry *new;
  		new = d_alloc(dir, &qname);
  		if (new) {
  			child = instantiate(dir->d_inode, new, task, ptr);
  			if (child)
  				dput(new);
  			else
  				child = new;
  		}
  	}
  	if (!child || IS_ERR(child) || !child->d_inode)
  		goto end_instantiate;
  	inode = child->d_inode;
  	if (inode) {
  		ino = inode->i_ino;
  		type = inode->i_mode >> 12;
  	}
  	dput(child);
  end_instantiate:
  	if (!ino)
  		ino = find_inode_number(dir, &qname);
  	if (!ino)
  		ino = 1;
  	return filldir(dirent, name, len, filp->f_pos, ino, type);
  }
  
  static unsigned name_to_int(struct dentry *dentry)
  {
  	const char *name = dentry->d_name.name;
  	int len = dentry->d_name.len;
  	unsigned n = 0;
  
  	if (len > 1 && *name == '0')
  		goto out;
  	while (len-- > 0) {
  		unsigned c = *name++ - '0';
  		if (c > 9)
  			goto out;
  		if (n >= (~0U-9)/10)
  			goto out;
  		n *= 10;
  		n += c;
  	}
  	return n;
  out:
  	return ~0U;
  }
  
  #define PROC_FDINFO_MAX 64
  
  static int proc_fd_info(struct inode *inode, struct path *path, char *info)
  {
  	struct task_struct *task = get_proc_task(inode);
  	struct files_struct *files = NULL;
  	struct file *file;
  	int fd = proc_fd(inode);
  
  	if (task) {
  		files = get_files_struct(task);
  		put_task_struct(task);
  	}
  	if (files) {
  		/*
  		 * We are not taking a ref to the file structure, so we must
  		 * hold ->file_lock.
  		 */
  		spin_lock(&files->file_lock);
  		file = fcheck_files(files, fd);
  		if (file) {
  			unsigned int f_flags;
  			struct fdtable *fdt;
  
  			fdt = files_fdtable(files);
  			f_flags = file->f_flags & ~O_CLOEXEC;
  			if (FD_ISSET(fd, fdt->close_on_exec))
  				f_flags |= O_CLOEXEC;
  
  			if (path) {
  				*path = file->f_path;
  				path_get(&file->f_path);
  			}
  			if (info)
  				snprintf(info, PROC_FDINFO_MAX,
  					 "pos:\t%lli\n"
  					 "flags:\t0%o\n",
  					 (long long) file->f_pos,
  					 f_flags);
  			spin_unlock(&files->file_lock);
  			put_files_struct(files);
  			return 0;
  		}
  		spin_unlock(&files->file_lock);
  		put_files_struct(files);
  	}
  	return -ENOENT;
  }
  
  static int proc_fd_link(struct inode *inode, struct path *path)
  {
  	return proc_fd_info(inode, path, NULL);
  }
  
  static int tid_fd_revalidate(struct dentry *dentry, struct nameidata *nd)
  {
  	struct inode *inode;
  	struct task_struct *task;
  	int fd;
  	struct files_struct *files;
  	const struct cred *cred;
  
  	if (nd && nd->flags & LOOKUP_RCU)
  		return -ECHILD;
  
  	inode = dentry->d_inode;
  	task = get_proc_task(inode);
  	fd = proc_fd(inode);
  
  	if (task) {
  		files = get_files_struct(task);
  		if (files) {
  			rcu_read_lock();
  			if (fcheck_files(files, fd)) {
  				rcu_read_unlock();
  				put_files_struct(files);
  				if (task_dumpable(task)) {
  					rcu_read_lock();
  					cred = __task_cred(task);
  					inode->i_uid = cred->euid;
  					inode->i_gid = cred->egid;
  					rcu_read_unlock();
  				} else {
  					inode->i_uid = 0;
  					inode->i_gid = 0;
  				}
  				inode->i_mode &= ~(S_ISUID | S_ISGID);
  				security_task_to_inode(task, inode);
  				put_task_struct(task);
  				return 1;
  			}
  			rcu_read_unlock();
  			put_files_struct(files);
  		}
  		put_task_struct(task);
  	}
  	d_drop(dentry);
  	return 0;
  }
  
  static const struct dentry_operations tid_fd_dentry_operations =
  {
  	.d_revalidate	= tid_fd_revalidate,
  	.d_delete	= pid_delete_dentry,
  };
  
  static struct dentry *proc_fd_instantiate(struct inode *dir,
  	struct dentry *dentry, struct task_struct *task, const void *ptr)
  {
  	unsigned fd = *(const unsigned *)ptr;
  	struct file *file;
  	struct files_struct *files;
   	struct inode *inode;
   	struct proc_inode *ei;
  	struct dentry *error = ERR_PTR(-ENOENT);
  
  	inode = proc_pid_make_inode(dir->i_sb, task);
  	if (!inode)
  		goto out;
  	ei = PROC_I(inode);
  	ei->fd = fd;
  	files = get_files_struct(task);
  	if (!files)
  		goto out_iput;
  	inode->i_mode = S_IFLNK;
  
  	/*
  	 * We are not taking a ref to the file structure, so we must
  	 * hold ->file_lock.
  	 */
  	spin_lock(&files->file_lock);
  	file = fcheck_files(files, fd);
  	if (!file)
  		goto out_unlock;
  	if (file->f_mode & FMODE_READ)
  		inode->i_mode |= S_IRUSR | S_IXUSR;
  	if (file->f_mode & FMODE_WRITE)
  		inode->i_mode |= S_IWUSR | S_IXUSR;
  	spin_unlock(&files->file_lock);
  	put_files_struct(files);
  
  	inode->i_op = &proc_pid_link_inode_operations;
  	inode->i_size = 64;
  	ei->op.proc_get_link = proc_fd_link;
  	d_set_d_op(dentry, &tid_fd_dentry_operations);
  	d_add(dentry, inode);
  	/* Close the race of the process dying before we return the dentry */
  	if (tid_fd_revalidate(dentry, NULL))
  		error = NULL;
  
   out:
  	return error;
  out_unlock:
  	spin_unlock(&files->file_lock);
  	put_files_struct(files);
  out_iput:
  	iput(inode);
  	goto out;
  }
  
  static struct dentry *proc_lookupfd_common(struct inode *dir,
  					   struct dentry *dentry,
  					   instantiate_t instantiate)
  {
  	struct task_struct *task = get_proc_task(dir);
  	unsigned fd = name_to_int(dentry);
  	struct dentry *result = ERR_PTR(-ENOENT);
  
  	if (!task)
  		goto out_no_task;
  	if (fd == ~0U)
  		goto out;
  
  	result = instantiate(dir, dentry, task, &fd);
  out:
  	put_task_struct(task);
  out_no_task:
  	return result;
  }
  
  static int proc_readfd_common(struct file * filp, void * dirent,
  			      filldir_t filldir, instantiate_t instantiate)
  {
  	struct dentry *dentry = filp->f_path.dentry;
  	struct inode *inode = dentry->d_inode;
  	struct task_struct *p = get_proc_task(inode);
  	unsigned int fd, ino;
  	int retval;
  	struct files_struct * files;
  
  	retval = -ENOENT;
  	if (!p)
  		goto out_no_task;
  	retval = 0;
  
  	fd = filp->f_pos;
  	switch (fd) {
  		case 0:
  			if (filldir(dirent, ".", 1, 0, inode->i_ino, DT_DIR) < 0)
  				goto out;
  			filp->f_pos++;
  		case 1:
  			ino = parent_ino(dentry);
  			if (filldir(dirent, "..", 2, 1, ino, DT_DIR) < 0)
  				goto out;
  			filp->f_pos++;
  		default:
  			files = get_files_struct(p);
  			if (!files)
  				goto out;
  			rcu_read_lock();
  			for (fd = filp->f_pos-2;
  			     fd < files_fdtable(files)->max_fds;
  			     fd++, filp->f_pos++) {
  				char name[PROC_NUMBUF];
  				int len;
  
  				if (!fcheck_files(files, fd))
  					continue;
  				rcu_read_unlock();
  
  				len = snprintf(name, sizeof(name), "%d", fd);
  				if (proc_fill_cache(filp, dirent, filldir,
  						    name, len, instantiate,
  						    p, &fd) < 0) {
  					rcu_read_lock();
  					break;
  				}
  				rcu_read_lock();
  			}
  			rcu_read_unlock();
  			put_files_struct(files);
  	}
  out:
  	put_task_struct(p);
  out_no_task:
  	return retval;
  }
  
  static struct dentry *proc_lookupfd(struct inode *dir, struct dentry *dentry,
  				    struct nameidata *nd)
  {
  	return proc_lookupfd_common(dir, dentry, proc_fd_instantiate);
  }
  
  static int proc_readfd(struct file *filp, void *dirent, filldir_t filldir)
  {
  	return proc_readfd_common(filp, dirent, filldir, proc_fd_instantiate);
  }
  
  static ssize_t proc_fdinfo_read(struct file *file, char __user *buf,
  				      size_t len, loff_t *ppos)
  {
  	char tmp[PROC_FDINFO_MAX];
  	int err = proc_fd_info(file->f_path.dentry->d_inode, NULL, tmp);
  	if (!err)
  		err = simple_read_from_buffer(buf, len, ppos, tmp, strlen(tmp));
  	return err;
  }
  
  static const struct file_operations proc_fdinfo_file_operations = {
  	.open           = nonseekable_open,
  	.read		= proc_fdinfo_read,
  	.llseek		= no_llseek,
  };
  
  static const struct file_operations proc_fd_operations = {
  	.read		= generic_read_dir,
  	.readdir	= proc_readfd,
  	.llseek		= default_llseek,
  };
  
  /*
   * /proc/pid/fd needs a special permission handler so that a process can still
   * access /proc/self/fd after it has executed a setuid().
   */
  static int proc_fd_permission(struct inode *inode, int mask, unsigned int flags)
  {
  	int rv = generic_permission(inode, mask, flags, NULL);
  	if (rv == 0)
  		return 0;
  	if (task_pid(current) == proc_pid(inode))
  		rv = 0;
  	return rv;
  }
  
  /*
   * proc directories can do almost nothing..
   */
  static const struct inode_operations proc_fd_inode_operations = {
  	.lookup		= proc_lookupfd,
  	.permission	= proc_fd_permission,
  	.setattr	= proc_setattr,
  };
  
  static struct dentry *proc_fdinfo_instantiate(struct inode *dir,
  	struct dentry *dentry, struct task_struct *task, const void *ptr)
  {
  	unsigned fd = *(unsigned *)ptr;
   	struct inode *inode;
   	struct proc_inode *ei;
  	struct dentry *error = ERR_PTR(-ENOENT);
  
  	inode = proc_pid_make_inode(dir->i_sb, task);
  	if (!inode)
  		goto out;
  	ei = PROC_I(inode);
  	ei->fd = fd;
  	inode->i_mode = S_IFREG | S_IRUSR;
  	inode->i_fop = &proc_fdinfo_file_operations;
  	d_set_d_op(dentry, &tid_fd_dentry_operations);
  	d_add(dentry, inode);
  	/* Close the race of the process dying before we return the dentry */
  	if (tid_fd_revalidate(dentry, NULL))
  		error = NULL;
  
   out:
  	return error;
  }
  
  static struct dentry *proc_lookupfdinfo(struct inode *dir,
  					struct dentry *dentry,
  					struct nameidata *nd)
  {
  	return proc_lookupfd_common(dir, dentry, proc_fdinfo_instantiate);
  }
  
  static int proc_readfdinfo(struct file *filp, void *dirent, filldir_t filldir)
  {
  	return proc_readfd_common(filp, dirent, filldir,
  				  proc_fdinfo_instantiate);
  }
  
  static const struct file_operations proc_fdinfo_operations = {
  	.read		= generic_read_dir,
  	.readdir	= proc_readfdinfo,
  	.llseek		= default_llseek,
  };
  
  /*
   * proc directories can do almost nothing..
   */
  static const struct inode_operations proc_fdinfo_inode_operations = {
  	.lookup		= proc_lookupfdinfo,
  	.setattr	= proc_setattr,
  };
  
  static struct dentry *proc_pident_instantiate(struct inode *dir,
  	struct dentry *dentry, struct task_struct *task, const void *ptr)
  {
  	const struct pid_entry *p = ptr;
  	struct inode *inode;
  	struct proc_inode *ei;
  	struct dentry *error = ERR_PTR(-ENOENT);
  
  	inode = proc_pid_make_inode(dir->i_sb, task);
  	if (!inode)
  		goto out;
  
  	ei = PROC_I(inode);
  	inode->i_mode = p->mode;
  	if (S_ISDIR(inode->i_mode))
  		inode->i_nlink = 2;	/* Use getattr to fix if necessary */
  	if (p->iop)
  		inode->i_op = p->iop;
  	if (p->fop)
  		inode->i_fop = p->fop;
  	ei->op = p->op;
  	d_set_d_op(dentry, &pid_dentry_operations);
  	d_add(dentry, inode);
  	/* Close the race of the process dying before we return the dentry */
  	if (pid_revalidate(dentry, NULL))
  		error = NULL;
  out:
  	return error;
  }
  
  static struct dentry *proc_pident_lookup(struct inode *dir,
  					 struct dentry *dentry,
  					 const struct pid_entry *ents,
  					 unsigned int nents)
  {
  	struct dentry *error;
  	struct task_struct *task = get_proc_task(dir);
  	const struct pid_entry *p, *last;
  
  	error = ERR_PTR(-ENOENT);
  
  	if (!task)
  		goto out_no_task;
  
  	/*
  	 * Yes, it does not scale. And it should not. Don't add
  	 * new entries into /proc/<tgid>/ without very good reasons.
  	 */
  	last = &ents[nents - 1];
  	for (p = ents; p <= last; p++) {
  		if (p->len != dentry->d_name.len)
  			continue;
  		if (!memcmp(dentry->d_name.name, p->name, p->len))
  			break;
  	}
  	if (p > last)
  		goto out;
  
  	error = proc_pident_instantiate(dir, dentry, task, p);
  out:
  	put_task_struct(task);
  out_no_task:
  	return error;
  }
  
  static int proc_pident_fill_cache(struct file *filp, void *dirent,
  	filldir_t filldir, struct task_struct *task, const struct pid_entry *p)
  {
  	return proc_fill_cache(filp, dirent, filldir, p->name, p->len,
  				proc_pident_instantiate, task, p);
  }
  
  static int proc_pident_readdir(struct file *filp,
  		void *dirent, filldir_t filldir,
  		const struct pid_entry *ents, unsigned int nents)
  {
  	int i;
  	struct dentry *dentry = filp->f_path.dentry;
  	struct inode *inode = dentry->d_inode;
  	struct task_struct *task = get_proc_task(inode);
  	const struct pid_entry *p, *last;
  	ino_t ino;
  	int ret;
  
  	ret = -ENOENT;
  	if (!task)
  		goto out_no_task;
  
  	ret = 0;
  	i = filp->f_pos;
  	switch (i) {
  	case 0:
  		ino = inode->i_ino;
  		if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0)
  			goto out;
  		i++;
  		filp->f_pos++;
  		/* fall through */
  	case 1:
  		ino = parent_ino(dentry);
  		if (filldir(dirent, "..", 2, i, ino, DT_DIR) < 0)
  			goto out;
  		i++;
  		filp->f_pos++;
  		/* fall through */
  	default:
  		i -= 2;
  		if (i >= nents) {
  			ret = 1;
  			goto out;
  		}
  		p = ents + i;
  		last = &ents[nents - 1];
  		while (p <= last) {
  			if (proc_pident_fill_cache(filp, dirent, filldir, task, p) < 0)
  				goto out;
  			filp->f_pos++;
  			p++;
  		}
  	}
  
  	ret = 1;
  out:
  	put_task_struct(task);
  out_no_task:
  	return ret;
  }
  
  #ifdef CONFIG_SECURITY
  static ssize_t proc_pid_attr_read(struct file * file, char __user * buf,
  				  size_t count, loff_t *ppos)
  {
  	struct inode * inode = file->f_path.dentry->d_inode;
  	char *p = NULL;
  	ssize_t length;
  	struct task_struct *task = get_proc_task(inode);
  
  	if (!task)
  		return -ESRCH;
  
  	length = security_getprocattr(task,
  				      (char*)file->f_path.dentry->d_name.name,
  				      &p);
  	put_task_struct(task);
  	if (length > 0)
  		length = simple_read_from_buffer(buf, count, ppos, p, length);
  	kfree(p);
  	return length;
  }
  
  static ssize_t proc_pid_attr_write(struct file * file, const char __user * buf,
  				   size_t count, loff_t *ppos)
  {
  	struct inode * inode = file->f_path.dentry->d_inode;
  	char *page;
  	ssize_t length;
  	struct task_struct *task = get_proc_task(inode);
  
  	length = -ESRCH;
  	if (!task)
  		goto out_no_task;
  	if (count > PAGE_SIZE)
  		count = PAGE_SIZE;
  
  	/* No partial writes. */
  	length = -EINVAL;
  	if (*ppos != 0)
  		goto out;
  
  	length = -ENOMEM;
  	page = (char*)__get_free_page(GFP_TEMPORARY);
  	if (!page)
  		goto out;
  
  	length = -EFAULT;
  	if (copy_from_user(page, buf, count))
  		goto out_free;
  
  	/* Guard against adverse ptrace interaction */
  	length = mutex_lock_interruptible(&task->signal->cred_guard_mutex);
  	if (length < 0)
  		goto out_free;
  
  	length = security_setprocattr(task,
  				      (char*)file->f_path.dentry->d_name.name,
  				      (void*)page, count);
  	mutex_unlock(&task->signal->cred_guard_mutex);
  out_free:
  	free_page((unsigned long) page);
  out:
  	put_task_struct(task);
  out_no_task:
  	return length;
  }
  
  static const struct file_operations proc_pid_attr_operations = {
  	.read		= proc_pid_attr_read,
  	.write		= proc_pid_attr_write,
  	.llseek		= generic_file_llseek,
  };
  
  static const struct pid_entry attr_dir_stuff[] = {
  	REG("current",    S_IRUGO|S_IWUGO, proc_pid_attr_operations),
  	REG("prev",       S_IRUGO,	   proc_pid_attr_operations),
  	REG("exec",       S_IRUGO|S_IWUGO, proc_pid_attr_operations),
  	REG("fscreate",   S_IRUGO|S_IWUGO, proc_pid_attr_operations),
  	REG("keycreate",  S_IRUGO|S_IWUGO, proc_pid_attr_operations),
  	REG("sockcreate", S_IRUGO|S_IWUGO, proc_pid_attr_operations),
  };
  
  static int proc_attr_dir_readdir(struct file * filp,
  			     void * dirent, filldir_t filldir)
  {
  	return proc_pident_readdir(filp,dirent,filldir,
  				   attr_dir_stuff,ARRAY_SIZE(attr_dir_stuff));
  }
  
  static const struct file_operations proc_attr_dir_operations = {
  	.read		= generic_read_dir,
  	.readdir	= proc_attr_dir_readdir,
  	.llseek		= default_llseek,
  };
  
  static struct dentry *proc_attr_dir_lookup(struct inode *dir,
  				struct dentry *dentry, struct nameidata *nd)
  {
  	return proc_pident_lookup(dir, dentry,
  				  attr_dir_stuff, ARRAY_SIZE(attr_dir_stuff));
  }
  
  static const struct inode_operations proc_attr_dir_inode_operations = {
  	.lookup		= proc_attr_dir_lookup,
  	.getattr	= pid_getattr,
  	.setattr	= proc_setattr,
  };
  
  #endif
  
  #ifdef CONFIG_ELF_CORE
  static ssize_t proc_coredump_filter_read(struct file *file, char __user *buf,
  					 size_t count, loff_t *ppos)
  {
  	struct task_struct *task = get_proc_task(file->f_dentry->d_inode);
  	struct mm_struct *mm;
  	char buffer[PROC_NUMBUF];
  	size_t len;
  	int ret;
  
  	if (!task)
  		return -ESRCH;
  
  	ret = 0;
  	mm = get_task_mm(task);
  	if (mm) {
  		len = snprintf(buffer, sizeof(buffer), "%08lx\n",
  			       ((mm->flags & MMF_DUMP_FILTER_MASK) >>
  				MMF_DUMP_FILTER_SHIFT));
  		mmput(mm);
  		ret = simple_read_from_buffer(buf, count, ppos, buffer, len);
  	}
  
  	put_task_struct(task);
  
  	return ret;
  }
  
  static ssize_t proc_coredump_filter_write(struct file *file,
  					  const char __user *buf,
  					  size_t count,
  					  loff_t *ppos)
  {
  	struct task_struct *task;
  	struct mm_struct *mm;
  	char buffer[PROC_NUMBUF], *end;
  	unsigned int val;
  	int ret;
  	int i;
  	unsigned long mask;
  
  	ret = -EFAULT;
  	memset(buffer, 0, sizeof(buffer));
  	if (count > sizeof(buffer) - 1)
  		count = sizeof(buffer) - 1;
  	if (copy_from_user(buffer, buf, count))
  		goto out_no_task;
  
  	ret = -EINVAL;
  	val = (unsigned int)simple_strtoul(buffer, &end, 0);
  	if (*end == '\n')
  		end++;
  	if (end - buffer == 0)
  		goto out_no_task;
  
  	ret = -ESRCH;
  	task = get_proc_task(file->f_dentry->d_inode);
  	if (!task)
  		goto out_no_task;
  
  	ret = end - buffer;
  	mm = get_task_mm(task);
  	if (!mm)
  		goto out_no_mm;
  
  	for (i = 0, mask = 1; i < MMF_DUMP_FILTER_BITS; i++, mask <<= 1) {
  		if (val & mask)
  			set_bit(i + MMF_DUMP_FILTER_SHIFT, &mm->flags);
  		else
  			clear_bit(i + MMF_DUMP_FILTER_SHIFT, &mm->flags);
  	}
  
  	mmput(mm);
   out_no_mm:
  	put_task_struct(task);
   out_no_task:
  	return ret;
  }
  
  static const struct file_operations proc_coredump_filter_operations = {
  	.read		= proc_coredump_filter_read,
  	.write		= proc_coredump_filter_write,
  	.llseek		= generic_file_llseek,
  };
  #endif
  
  /*
   * /proc/self:
   */
  static int proc_self_readlink(struct dentry *dentry, char __user *buffer,
  			      int buflen)
  {
  	struct pid_namespace *ns = dentry->d_sb->s_fs_info;
  	pid_t tgid = task_tgid_nr_ns(current, ns);
  	char tmp[PROC_NUMBUF];
  	if (!tgid)
  		return -ENOENT;
  	sprintf(tmp, "%d", tgid);
  	return vfs_readlink(dentry,buffer,buflen,tmp);
  }
  
  static void *proc_self_follow_link(struct dentry *dentry, struct nameidata *nd)
  {
  	struct pid_namespace *ns = dentry->d_sb->s_fs_info;
  	pid_t tgid = task_tgid_nr_ns(current, ns);
  	char *name = ERR_PTR(-ENOENT);
  	if (tgid) {
  		name = __getname();
  		if (!name)
  			name = ERR_PTR(-ENOMEM);
  		else
  			sprintf(name, "%d", tgid);
  	}
  	nd_set_link(nd, name);
  	return NULL;
  }
  
  static void proc_self_put_link(struct dentry *dentry, struct nameidata *nd,
  				void *cookie)
  {
  	char *s = nd_get_link(nd);
  	if (!IS_ERR(s))
  		__putname(s);
  }
  
  static const struct inode_operations proc_self_inode_operations = {
  	.readlink	= proc_self_readlink,
  	.follow_link	= proc_self_follow_link,
  	.put_link	= proc_self_put_link,
  };
  
  /*
   * proc base
   *
   * These are the directory entries in the root directory of /proc
   * that properly belong to the /proc filesystem, as they describe
   * describe something that is process related.
   */
  static const struct pid_entry proc_base_stuff[] = {
  	NOD("self", S_IFLNK|S_IRWXUGO,
  		&proc_self_inode_operations, NULL, {}),
  };
  
  static struct dentry *proc_base_instantiate(struct inode *dir,
  	struct dentry *dentry, struct task_struct *task, const void *ptr)
  {
  	const struct pid_entry *p = ptr;
  	struct inode *inode;
  	struct proc_inode *ei;
  	struct dentry *error;
  
  	/* Allocate the inode */
  	error = ERR_PTR(-ENOMEM);
  	inode = new_inode(dir->i_sb);
  	if (!inode)
  		goto out;
  
  	/* Initialize the inode */
  	ei = PROC_I(inode);
  	inode->i_ino = get_next_ino();
  	inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
  
  	/*
  	 * grab the reference to the task.
  	 */
  	ei->pid = get_task_pid(task, PIDTYPE_PID);
  	if (!ei->pid)
  		goto out_iput;
  
  	inode->i_mode = p->mode;
  	if (S_ISDIR(inode->i_mode))
  		inode->i_nlink = 2;
  	if (S_ISLNK(inode->i_mode))
  		inode->i_size = 64;
  	if (p->iop)
  		inode->i_op = p->iop;
  	if (p->fop)
  		inode->i_fop = p->fop;
  	ei->op = p->op;
  	d_add(dentry, inode);
  	error = NULL;
  out:
  	return error;
  out_iput:
  	iput(inode);
  	goto out;
  }
  
  static struct dentry *proc_base_lookup(struct inode *dir, struct dentry *dentry)
  {
  	struct dentry *error;
  	struct task_struct *task = get_proc_task(dir);
  	const struct pid_entry *p, *last;
  
  	error = ERR_PTR(-ENOENT);
  
  	if (!task)
  		goto out_no_task;
  
  	/* Lookup the directory entry */
  	last = &proc_base_stuff[ARRAY_SIZE(proc_base_stuff) - 1];
  	for (p = proc_base_stuff; p <= last; p++) {
  		if (p->len != dentry->d_name.len)
  			continue;
  		if (!memcmp(dentry->d_name.name, p->name, p->len))
  			break;
  	}
  	if (p > last)
  		goto out;
  
  	error = proc_base_instantiate(dir, dentry, task, p);
  
  out:
  	put_task_struct(task);
  out_no_task:
  	return error;
  }
  
  static int proc_base_fill_cache(struct file *filp, void *dirent,
  	filldir_t filldir, struct task_struct *task, const struct pid_entry *p)
  {
  	return proc_fill_cache(filp, dirent, filldir, p->name, p->len,
  				proc_base_instantiate, task, p);
  }
  
  #ifdef CONFIG_TASK_IO_ACCOUNTING
  static int do_io_accounting(struct task_struct *task, char *buffer, int whole)
  {
  	struct task_io_accounting acct = task->ioac;
  	unsigned long flags;
  	int result;
  
  	result = mutex_lock_killable(&task->signal->cred_guard_mutex);
  	if (result)
  		return result;
  
  	if (!ptrace_may_access(task, PTRACE_MODE_READ)) {
  		result = -EACCES;
  		goto out_unlock;
  	}
  
  	if (whole && lock_task_sighand(task, &flags)) {
  		struct task_struct *t = task;
  
  		task_io_accounting_add(&acct, &task->signal->ioac);
  		while_each_thread(task, t)
  			task_io_accounting_add(&acct, &t->ioac);
  
  		unlock_task_sighand(task, &flags);
  	}
  	result = sprintf(buffer,
  			"rchar: %llu\n"
  			"wchar: %llu\n"
  			"syscr: %llu\n"
  			"syscw: %llu\n"
  			"read_bytes: %llu\n"
  			"write_bytes: %llu\n"
  			"cancelled_write_bytes: %llu\n",
  			(unsigned long long)acct.rchar,
  			(unsigned long long)acct.wchar,
  			(unsigned long long)acct.syscr,
  			(unsigned long long)acct.syscw,
  			(unsigned long long)acct.read_bytes,
  			(unsigned long long)acct.write_bytes,
  			(unsigned long long)acct.cancelled_write_bytes);
  out_unlock:
  	mutex_unlock(&task->signal->cred_guard_mutex);
  	return result;
  }
  
  static int proc_tid_io_accounting(struct task_struct *task, char *buffer)
  {
  	return do_io_accounting(task, buffer, 0);
  }
  
  static int proc_tgid_io_accounting(struct task_struct *task, char *buffer)
  {
  	return do_io_accounting(task, buffer, 1);
  }
  #endif /* CONFIG_TASK_IO_ACCOUNTING */
  
  static int proc_pid_personality(struct seq_file *m, struct pid_namespace *ns,
  				struct pid *pid, struct task_struct *task)
  {
  	int err = lock_trace(task);
  	if (!err) {
  		seq_printf(m, "%08x\n", task->personality);
  		unlock_trace(task);
  	}
  	return err;
  }
  
  /*
   * Thread groups
   */
  static const struct file_operations proc_task_operations;
  static const struct inode_operations proc_task_inode_operations;
  
  static const struct pid_entry tgid_base_stuff[] = {
  	DIR("task",       S_IRUGO|S_IXUGO, proc_task_inode_operations, proc_task_operations),
  	DIR("fd",         S_IRUSR|S_IXUSR, proc_fd_inode_operations, proc_fd_operations),
  	DIR("fdinfo",     S_IRUSR|S_IXUSR, proc_fdinfo_inode_operations, proc_fdinfo_operations),
  	DIR("ns",	  S_IRUSR|S_IXUGO, proc_ns_dir_inode_operations, proc_ns_dir_operations),
  #ifdef CONFIG_NET
  	DIR("net",        S_IRUGO|S_IXUGO, proc_net_inode_operations, proc_net_operations),
  #endif
  	REG("environ",    S_IRUSR, proc_environ_operations),
  	INF("auxv",       S_IRUSR, proc_pid_auxv),
  	ONE("status",     S_IRUGO, proc_pid_status),
  	ONE("personality", S_IRUGO, proc_pid_personality),
  	INF("limits",	  S_IRUGO, proc_pid_limits),
  #ifdef CONFIG_SCHED_DEBUG
  	REG("sched",      S_IRUGO|S_IWUSR, proc_pid_sched_operations),
  #endif
  #ifdef CONFIG_SCHED_AUTOGROUP
  	REG("autogroup",  S_IRUGO|S_IWUSR, proc_pid_sched_autogroup_operations),
  #endif
  	REG("comm",      S_IRUGO|S_IWUSR, proc_pid_set_comm_operations),
  #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
  	INF("syscall",    S_IRUGO, proc_pid_syscall),
  #endif
  	INF("cmdline",    S_IRUGO, proc_pid_cmdline),
  	ONE("stat",       S_IRUGO, proc_tgid_stat),
  	ONE("statm",      S_IRUGO, proc_pid_statm),
  	REG("maps",       S_IRUGO, proc_maps_operations),
  #ifdef CONFIG_NUMA
  	REG("numa_maps",  S_IRUGO, proc_numa_maps_operations),
  #endif
  	REG("mem",        S_IRUSR|S_IWUSR, proc_mem_operations),
  	LNK("cwd",        proc_cwd_link),
  	LNK("root",       proc_root_link),
  	LNK("exe",        proc_exe_link),
  	REG("mounts",     S_IRUGO, proc_mounts_operations),
  	REG("mountinfo",  S_IRUGO, proc_mountinfo_operations),
  	REG("mountstats", S_IRUSR, proc_mountstats_operations),
  #ifdef CONFIG_PROC_PAGE_MONITOR
  	REG("clear_refs", S_IWUSR, proc_clear_refs_operations),
  	REG("smaps",      S_IRUGO, proc_smaps_operations),
  	REG("pagemap",    S_IRUGO, proc_pagemap_operations),
  #endif
  #ifdef CONFIG_SECURITY
  	DIR("attr",       S_IRUGO|S_IXUGO, proc_attr_dir_inode_operations, proc_attr_dir_operations),
  #endif
  #ifdef CONFIG_KALLSYMS
  	INF("wchan",      S_IRUGO, proc_pid_wchan),
  #endif
  #ifdef CONFIG_STACKTRACE
  	ONE("stack",      S_IRUGO, proc_pid_stack),
  #endif
  #ifdef CONFIG_SCHEDSTATS
  	INF("schedstat",  S_IRUGO, proc_pid_schedstat),
  #endif
  #ifdef CONFIG_LATENCYTOP
  	REG("latency",  S_IRUGO, proc_lstats_operations),
  #endif
  #ifdef CONFIG_PROC_PID_CPUSET
  	REG("cpuset",     S_IRUGO, proc_cpuset_operations),
  #endif
  #ifdef CONFIG_CGROUPS
  	REG("cgroup",  S_IRUGO, proc_cgroup_operations),
  #endif
  	INF("oom_score",  S_IRUGO, proc_oom_score),
  	ANDROID("oom_adj",S_IRUGO|S_IWUSR, oom_adjust),
  	REG("oom_score_adj", S_IRUGO|S_IWUSR, proc_oom_score_adj_operations),
  #ifdef CONFIG_AUDITSYSCALL
  	REG("loginuid",   S_IWUSR|S_IRUGO, proc_loginuid_operations),
  	REG("sessionid",  S_IRUGO, proc_sessionid_operations),
  #endif
  #ifdef CONFIG_FAULT_INJECTION
  	REG("make-it-fail", S_IRUGO|S_IWUSR, proc_fault_inject_operations),
  #endif
  #ifdef CONFIG_ELF_CORE
  	REG("coredump_filter", S_IRUGO|S_IWUSR, proc_coredump_filter_operations),
  #endif
  #ifdef CONFIG_TASK_IO_ACCOUNTING
  	INF("io",	S_IRUSR, proc_tgid_io_accounting),
  #endif
  #ifdef CONFIG_HARDWALL
  	INF("hardwall",   S_IRUGO, proc_pid_hardwall),
  #endif
  };
  
  static int proc_tgid_base_readdir(struct file * filp,
  			     void * dirent, filldir_t filldir)
  {
  	return proc_pident_readdir(filp,dirent,filldir,
  				   tgid_base_stuff,ARRAY_SIZE(tgid_base_stuff));
  }
  
  static const struct file_operations proc_tgid_base_operations = {
  	.read		= generic_read_dir,
  	.readdir	= proc_tgid_base_readdir,
  	.llseek		= default_llseek,
  };
  
  static struct dentry *proc_tgid_base_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd){
  	return proc_pident_lookup(dir, dentry,
  				  tgid_base_stuff, ARRAY_SIZE(tgid_base_stuff));
  }
  
  static const struct inode_operations proc_tgid_base_inode_operations = {
  	.lookup		= proc_tgid_base_lookup,
  	.getattr	= pid_getattr,
  	.setattr	= proc_setattr,
  };
  
  static void proc_flush_task_mnt(struct vfsmount *mnt, pid_t pid, pid_t tgid)
  {
  	struct dentry *dentry, *leader, *dir;
  	char buf[PROC_NUMBUF];
  	struct qstr name;
  
  	name.name = buf;
  	name.len = snprintf(buf, sizeof(buf), "%d", pid);
  	dentry = d_hash_and_lookup(mnt->mnt_root, &name);
  	if (dentry) {
  		shrink_dcache_parent(dentry);
  		d_drop(dentry);
  		dput(dentry);
  	}
  
  	name.name = buf;
  	name.len = snprintf(buf, sizeof(buf), "%d", tgid);
  	leader = d_hash_and_lookup(mnt->mnt_root, &name);
  	if (!leader)
  		goto out;
  
  	name.name = "task";
  	name.len = strlen(name.name);
  	dir = d_hash_and_lookup(leader, &name);
  	if (!dir)
  		goto out_put_leader;
  
  	name.name = buf;
  	name.len = snprintf(buf, sizeof(buf), "%d", pid);
  	dentry = d_hash_and_lookup(dir, &name);
  	if (dentry) {
  		shrink_dcache_parent(dentry);
  		d_drop(dentry);
  		dput(dentry);
  	}
  
  	dput(dir);
  out_put_leader:
  	dput(leader);
  out:
  	return;
  }
  
  /**
   * proc_flush_task -  Remove dcache entries for @task from the /proc dcache.
   * @task: task that should be flushed.
   *
   * When flushing dentries from proc, one needs to flush them from global
   * proc (proc_mnt) and from all the namespaces' procs this task was seen
   * in. This call is supposed to do all of this job.
   *
   * Looks in the dcache for
   * /proc/@pid
   * /proc/@tgid/task/@pid
   * if either directory is present flushes it and all of it'ts children
   * from the dcache.
   *
   * It is safe and reasonable to cache /proc entries for a task until
   * that task exits.  After that they just clog up the dcache with
   * useless entries, possibly causing useful dcache entries to be
   * flushed instead.  This routine is proved to flush those useless
   * dcache entries at process exit time.
   *
   * NOTE: This routine is just an optimization so it does not guarantee
   *       that no dcache entries will exist at process exit time it
   *       just makes it very unlikely that any will persist.
   */
  
  void proc_flush_task(struct task_struct *task)
  {
  	int i;
  	struct pid *pid, *tgid;
  	struct upid *upid;
  
  	pid = task_pid(task);
  	tgid = task_tgid(task);
  
  	for (i = 0; i <= pid->level; i++) {
  		upid = &pid->numbers[i];
  		proc_flush_task_mnt(upid->ns->proc_mnt, upid->nr,
  					tgid->numbers[i].nr);
  	}
  
  	upid = &pid->numbers[pid->level];
  	if (upid->nr == 1)
  		pid_ns_release_proc(upid->ns);
  }
  
  static struct dentry *proc_pid_instantiate(struct inode *dir,
  					   struct dentry * dentry,
  					   struct task_struct *task, const void *ptr)
  {
  	struct dentry *error = ERR_PTR(-ENOENT);
  	struct inode *inode;
  
  	inode = proc_pid_make_inode(dir->i_sb, task);
  	if (!inode)
  		goto out;
  
  	inode->i_mode = S_IFDIR|S_IRUGO|S_IXUGO;
  	inode->i_op = &proc_tgid_base_inode_operations;
  	inode->i_fop = &proc_tgid_base_operations;
  	inode->i_flags|=S_IMMUTABLE;
  
  	inode->i_nlink = 2 + pid_entry_count_dirs(tgid_base_stuff,
  		ARRAY_SIZE(tgid_base_stuff));
  
  	d_set_d_op(dentry, &pid_dentry_operations);
  
  	d_add(dentry, inode);
  	/* Close the race of the process dying before we return the dentry */
  	if (pid_revalidate(dentry, NULL))
  		error = NULL;
  out:
  	return error;
  }
  
  struct dentry *proc_pid_lookup(struct inode *dir, struct dentry * dentry, struct nameidata *nd)
  {
  	struct dentry *result;
  	struct task_struct *task;
  	unsigned tgid;
  	struct pid_namespace *ns;
  
  	result = proc_base_lookup(dir, dentry);
  	if (!IS_ERR(result) || PTR_ERR(result) != -ENOENT)
  		goto out;
  
  	tgid = name_to_int(dentry);
  	if (tgid == ~0U)
  		goto out;
  
  	ns = dentry->d_sb->s_fs_info;
  	rcu_read_lock();
  	task = find_task_by_pid_ns(tgid, ns);
  	if (task)
  		get_task_struct(task);
  	rcu_read_unlock();
  	if (!task)
  		goto out;
  
  	result = proc_pid_instantiate(dir, dentry, task, NULL);
  	put_task_struct(task);
  out:
  	return result;
  }
  
  /*
   * Find the first task with tgid >= tgid
   *
   */
  struct tgid_iter {
  	unsigned int tgid;
  	struct task_struct *task;
  };
  static struct tgid_iter next_tgid(struct pid_namespace *ns, struct tgid_iter iter)
  {
  	struct pid *pid;
  
  	if (iter.task)
  		put_task_struct(iter.task);
  	rcu_read_lock();
  retry:
  	iter.task = NULL;
  	pid = find_ge_pid(iter.tgid, ns);
  	if (pid) {
  		iter.tgid = pid_nr_ns(pid, ns);
  		iter.task = pid_task(pid, PIDTYPE_PID);
  		/* What we to know is if the pid we have find is the
  		 * pid of a thread_group_leader.  Testing for task
  		 * being a thread_group_leader is the obvious thing
  		 * todo but there is a window when it fails, due to
  		 * the pid transfer logic in de_thread.
  		 *
  		 * So we perform the straight forward test of seeing
  		 * if the pid we have found is the pid of a thread
  		 * group leader, and don't worry if the task we have
  		 * found doesn't happen to be a thread group leader.
  		 * As we don't care in the case of readdir.
  		 */
  		if (!iter.task || !has_group_leader_pid(iter.task)) {
  			iter.tgid += 1;
  			goto retry;
  		}
  		get_task_struct(iter.task);
  	}
  	rcu_read_unlock();
  	return iter;
  }
  
  #define TGID_OFFSET (FIRST_PROCESS_ENTRY + ARRAY_SIZE(proc_base_stuff))
  
  static int proc_pid_fill_cache(struct file *filp, void *dirent, filldir_t filldir,
  	struct tgid_iter iter)
  {
  	char name[PROC_NUMBUF];
  	int len = snprintf(name, sizeof(name), "%d", iter.tgid);
  	return proc_fill_cache(filp, dirent, filldir, name, len,
  				proc_pid_instantiate, iter.task, NULL);
  }
  
  /* for the /proc/ directory itself, after non-process stuff has been done */
  int proc_pid_readdir(struct file * filp, void * dirent, filldir_t filldir)
  {
  	unsigned int nr;
  	struct task_struct *reaper;
  	struct tgid_iter iter;
  	struct pid_namespace *ns;
  
  	if (filp->f_pos >= PID_MAX_LIMIT + TGID_OFFSET)
  		goto out_no_task;
  	nr = filp->f_pos - FIRST_PROCESS_ENTRY;
  
  	reaper = get_proc_task(filp->f_path.dentry->d_inode);
  	if (!reaper)
  		goto out_no_task;
  
  	for (; nr < ARRAY_SIZE(proc_base_stuff); filp->f_pos++, nr++) {
  		const struct pid_entry *p = &proc_base_stuff[nr];
  		if (proc_base_fill_cache(filp, dirent, filldir, reaper, p) < 0)
  			goto out;
  	}
  
  	ns = filp->f_dentry->d_sb->s_fs_info;
  	iter.task = NULL;
  	iter.tgid = filp->f_pos - TGID_OFFSET;
  	for (iter = next_tgid(ns, iter);
  	     iter.task;
  	     iter.tgid += 1, iter = next_tgid(ns, iter)) {
  		filp->f_pos = iter.tgid + TGID_OFFSET;
  		if (proc_pid_fill_cache(filp, dirent, filldir, iter) < 0) {
  			put_task_struct(iter.task);
  			goto out;
  		}
  	}
  	filp->f_pos = PID_MAX_LIMIT + TGID_OFFSET;
  out:
  	put_task_struct(reaper);
  out_no_task:
  	return 0;
  }
  
  /*
   * Tasks
   */
  static const struct pid_entry tid_base_stuff[] = {
  	DIR("fd",        S_IRUSR|S_IXUSR, proc_fd_inode_operations, proc_fd_operations),
  	DIR("fdinfo",    S_IRUSR|S_IXUSR, proc_fdinfo_inode_operations, proc_fdinfo_operations),
  	DIR("ns",	 S_IRUSR|S_IXUGO, proc_ns_dir_inode_operations, proc_ns_dir_operations),
  	REG("environ",   S_IRUSR, proc_environ_operations),
  	INF("auxv",      S_IRUSR, proc_pid_auxv),
  	ONE("status",    S_IRUGO, proc_pid_status),
  	ONE("personality", S_IRUGO, proc_pid_personality),
  	INF("limits",	 S_IRUGO, proc_pid_limits),
  #ifdef CONFIG_SCHED_DEBUG
  	REG("sched",     S_IRUGO|S_IWUSR, proc_pid_sched_operations),
  #endif
  	REG("comm",      S_IRUGO|S_IWUSR, proc_pid_set_comm_operations),
  #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
  	INF("syscall",   S_IRUGO, proc_pid_syscall),
  #endif
  	INF("cmdline",   S_IRUGO, proc_pid_cmdline),
  	ONE("stat",      S_IRUGO, proc_tid_stat),
  	ONE("statm",     S_IRUGO, proc_pid_statm),
  	REG("maps",      S_IRUGO, proc_maps_operations),
  #ifdef CONFIG_NUMA
  	REG("numa_maps", S_IRUGO, proc_numa_maps_operations),
  #endif
  	REG("mem",       S_IRUSR|S_IWUSR, proc_mem_operations),
  	LNK("cwd",       proc_cwd_link),
  	LNK("root",      proc_root_link),
  	LNK("exe",       proc_exe_link),
  	REG("mounts",    S_IRUGO, proc_mounts_operations),
  	REG("mountinfo",  S_IRUGO, proc_mountinfo_operations),
  #ifdef CONFIG_PROC_PAGE_MONITOR
  	REG("clear_refs", S_IWUSR, proc_clear_refs_operations),
  	REG("smaps",     S_IRUGO, proc_smaps_operations),
  	REG("pagemap",    S_IRUGO, proc_pagemap_operations),
  #endif
  #ifdef CONFIG_SECURITY
  	DIR("attr",      S_IRUGO|S_IXUGO, proc_attr_dir_inode_operations, proc_attr_dir_operations),
  #endif
  #ifdef CONFIG_KALLSYMS
  	INF("wchan",     S_IRUGO, proc_pid_wchan),
  #endif
  #ifdef CONFIG_STACKTRACE
  	ONE("stack",      S_IRUGO, proc_pid_stack),
  #endif
  #ifdef CONFIG_SCHEDSTATS
  	INF("schedstat", S_IRUGO, proc_pid_schedstat),
  #endif
  #ifdef CONFIG_LATENCYTOP
  	REG("latency",  S_IRUGO, proc_lstats_operations),
  #endif
  #ifdef CONFIG_PROC_PID_CPUSET
  	REG("cpuset",    S_IRUGO, proc_cpuset_operations),
  #endif
  #ifdef CONFIG_CGROUPS
  	REG("cgroup",  S_IRUGO, proc_cgroup_operations),
  #endif
  	INF("oom_score", S_IRUGO, proc_oom_score),
  	REG("oom_adj",   S_IRUGO|S_IWUSR, proc_oom_adjust_operations),
  	REG("oom_score_adj", S_IRUGO|S_IWUSR, proc_oom_score_adj_operations),
  #ifdef CONFIG_AUDITSYSCALL
  	REG("loginuid",  S_IWUSR|S_IRUGO, proc_loginuid_operations),
  	REG("sessionid",  S_IRUGO, proc_sessionid_operations),
  #endif
  #ifdef CONFIG_FAULT_INJECTION
  	REG("make-it-fail", S_IRUGO|S_IWUSR, proc_fault_inject_operations),
  #endif
  #ifdef CONFIG_TASK_IO_ACCOUNTING
  	INF("io",	S_IRUSR, proc_tid_io_accounting),
  #endif
  #ifdef CONFIG_HARDWALL
  	INF("hardwall",   S_IRUGO, proc_pid_hardwall),
  #endif
  };
  
  static int proc_tid_base_readdir(struct file * filp,
  			     void * dirent, filldir_t filldir)
  {
  	return proc_pident_readdir(filp,dirent,filldir,
  				   tid_base_stuff,ARRAY_SIZE(tid_base_stuff));
  }
  
  static struct dentry *proc_tid_base_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd){
  	return proc_pident_lookup(dir, dentry,
  				  tid_base_stuff, ARRAY_SIZE(tid_base_stuff));
  }
  
  static const struct file_operations proc_tid_base_operations = {
  	.read		= generic_read_dir,
  	.readdir	= proc_tid_base_readdir,
  	.llseek		= default_llseek,
  };
  
  static const struct inode_operations proc_tid_base_inode_operations = {
  	.lookup		= proc_tid_base_lookup,
  	.getattr	= pid_getattr,
  	.setattr	= proc_setattr,
  };
  
  static struct dentry *proc_task_instantiate(struct inode *dir,
  	struct dentry *dentry, struct task_struct *task, const void *ptr)
  {
  	struct dentry *error = ERR_PTR(-ENOENT);
  	struct inode *inode;
  	inode = proc_pid_make_inode(dir->i_sb, task);
  
  	if (!inode)
  		goto out;
  	inode->i_mode = S_IFDIR|S_IRUGO|S_IXUGO;
  	inode->i_op = &proc_tid_base_inode_operations;
  	inode->i_fop = &proc_tid_base_operations;
  	inode->i_flags|=S_IMMUTABLE;
  
  	inode->i_nlink = 2 + pid_entry_count_dirs(tid_base_stuff,
  		ARRAY_SIZE(tid_base_stuff));
  
  	d_set_d_op(dentry, &pid_dentry_operations);
  
  	d_add(dentry, inode);
  	/* Close the race of the process dying before we return the dentry */
  	if (pid_revalidate(dentry, NULL))
  		error = NULL;
  out:
  	return error;
  }
  
  static struct dentry *proc_task_lookup(struct inode *dir, struct dentry * dentry, struct nameidata *nd)
  {
  	struct dentry *result = ERR_PTR(-ENOENT);
  	struct task_struct *task;
  	struct task_struct *leader = get_proc_task(dir);
  	unsigned tid;
  	struct pid_namespace *ns;
  
  	if (!leader)
  		goto out_no_task;
  
  	tid = name_to_int(dentry);
  	if (tid == ~0U)
  		goto out;
  
  	ns = dentry->d_sb->s_fs_info;
  	rcu_read_lock();
  	task = find_task_by_pid_ns(tid, ns);
  	if (task)
  		get_task_struct(task);
  	rcu_read_unlock();
  	if (!task)
  		goto out;
  	if (!same_thread_group(leader, task))
  		goto out_drop_task;
  
  	result = proc_task_instantiate(dir, dentry, task, NULL);
  out_drop_task:
  	put_task_struct(task);
  out:
  	put_task_struct(leader);
  out_no_task:
  	return result;
  }
  
  /*
   * Find the first tid of a thread group to return to user space.
   *
   * Usually this is just the thread group leader, but if the users
   * buffer was too small or there was a seek into the middle of the
   * directory we have more work todo.
   *
   * In the case of a short read we start with find_task_by_pid.
   *
   * In the case of a seek we start with the leader and walk nr
   * threads past it.
   */
  static struct task_struct *first_tid(struct task_struct *leader,
  		int tid, int nr, struct pid_namespace *ns)
  {
  	struct task_struct *pos;
  
  	rcu_read_lock();
  	/* Attempt to start with the pid of a thread */
  	if (tid && (nr > 0)) {
  		pos = find_task_by_pid_ns(tid, ns);
  		if (pos && (pos->group_leader == leader))
  			goto found;
  	}
  
  	/* If nr exceeds the number of threads there is nothing todo */
  	pos = NULL;
  	if (nr && nr >= get_nr_threads(leader))
  		goto out;
  
  	/* If we haven't found our starting place yet start
  	 * with the leader and walk nr threads forward.
  	 */
  	for (pos = leader; nr > 0; --nr) {
  		pos = next_thread(pos);
  		if (pos == leader) {
  			pos = NULL;
  			goto out;
  		}
  	}
  found:
  	get_task_struct(pos);
  out:
  	rcu_read_unlock();
  	return pos;
  }
  
  /*
   * Find the next thread in the thread list.
   * Return NULL if there is an error or no next thread.
   *
   * The reference to the input task_struct is released.
   */
  static struct task_struct *next_tid(struct task_struct *start)
  {
  	struct task_struct *pos = NULL;
  	rcu_read_lock();
  	if (pid_alive(start)) {
  		pos = next_thread(start);
  		if (thread_group_leader(pos))
  			pos = NULL;
  		else
  			get_task_struct(pos);
  	}
  	rcu_read_unlock();
  	put_task_struct(start);
  	return pos;
  }
  
  static int proc_task_fill_cache(struct file *filp, void *dirent, filldir_t filldir,
  	struct task_struct *task, int tid)
  {
  	char name[PROC_NUMBUF];
  	int len = snprintf(name, sizeof(name), "%d", tid);
  	return proc_fill_cache(filp, dirent, filldir, name, len,
  				proc_task_instantiate, task, NULL);
  }
  
  /* for the /proc/TGID/task/ directories */
  static int proc_task_readdir(struct file * filp, void * dirent, filldir_t filldir)
  {
  	struct dentry *dentry = filp->f_path.dentry;
  	struct inode *inode = dentry->d_inode;
  	struct task_struct *leader = NULL;
  	struct task_struct *task;
  	int retval = -ENOENT;
  	ino_t ino;
  	int tid;
  	struct pid_namespace *ns;
  
  	task = get_proc_task(inode);
  	if (!task)
  		goto out_no_task;
  	rcu_read_lock();
  	if (pid_alive(task)) {
  		leader = task->group_leader;
  		get_task_struct(leader);
  	}
  	rcu_read_unlock();
  	put_task_struct(task);
  	if (!leader)
  		goto out_no_task;
  	retval = 0;
  
  	switch ((unsigned long)filp->f_pos) {
  	case 0:
  		ino = inode->i_ino;
  		if (filldir(dirent, ".", 1, filp->f_pos, ino, DT_DIR) < 0)
  			goto out;
  		filp->f_pos++;
  		/* fall through */
  	case 1:
  		ino = parent_ino(dentry);
  		if (filldir(dirent, "..", 2, filp->f_pos, ino, DT_DIR) < 0)
  			goto out;
  		filp->f_pos++;
  		/* fall through */
  	}
  
  	/* f_version caches the tgid value that the last readdir call couldn't
  	 * return. lseek aka telldir automagically resets f_version to 0.
  	 */
  	ns = filp->f_dentry->d_sb->s_fs_info;
  	tid = (int)filp->f_version;
  	filp->f_version = 0;
  	for (task = first_tid(leader, tid, filp->f_pos - 2, ns);
  	     task;
  	     task = next_tid(task), filp->f_pos++) {
  		tid = task_pid_nr_ns(task, ns);
  		if (proc_task_fill_cache(filp, dirent, filldir, task, tid) < 0) {
  			/* returning this tgid failed, save it as the first
  			 * pid for the next readir call */
  			filp->f_version = (u64)tid;
  			put_task_struct(task);
  			break;
  		}
  	}
  out:
  	put_task_struct(leader);
  out_no_task:
  	return retval;
  }
  
  static int proc_task_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
  {
  	struct inode *inode = dentry->d_inode;
  	struct task_struct *p = get_proc_task(inode);
  	generic_fillattr(inode, stat);
  
  	if (p) {
  		stat->nlink += get_nr_threads(p);
  		put_task_struct(p);
  	}
  
  	return 0;
  }
  
  static const struct inode_operations proc_task_inode_operations = {
  	.lookup		= proc_task_lookup,
  	.getattr	= proc_task_getattr,
  	.setattr	= proc_setattr,
  };
  
  static const struct file_operations proc_task_operations = {
  	.read		= generic_read_dir,
  	.readdir	= proc_task_readdir,
  	.llseek		= default_llseek,
  };
  