text: /* SPDX-License-Identifier: GPL-2.0 */
  #ifndef __LINUX_SMP_H
  #define __LINUX_SMP_H
  
  /*
   *	Generic SMP support
   *		Alan Cox. <alan@redhat.com>
   */
  
  #include <linux/errno.h>
  #include <linux/types.h>
  #include <linux/list.h>
  #include <linux/cpumask.h>
  #include <linux/init.h>
  #include <linux/smp_types.h>
  
  typedef void (*smp_call_func_t)(void *info);
  typedef bool (*smp_cond_func_t)(int cpu, void *info);
  
  /*
   * structure shares (partial) layout with struct irq_work
   */
  struct __call_single_data {
  	struct __call_single_node node;
  	smp_call_func_t func;
  	void *info;
  };
  
  #define CSD_INIT(_func, _info) \
  	(struct __call_single_data){ .func = (_func), .info = (_info), }
  
  /* Use __aligned() to avoid to use 2 cache lines for 1 csd */
  typedef struct __call_single_data call_single_data_t
  	__aligned(sizeof(struct __call_single_data));
  
  #define INIT_CSD(_csd, _func, _info)		\
  do {						\
  	*(_csd) = CSD_INIT((_func), (_info));	\
  } while (0)
  
  /*
   * Enqueue a llist_node on the call_single_queue; be very careful, read
   * flush_smp_call_function_queue() in detail.
   */
  extern void __smp_call_single_queue(int cpu, struct llist_node *node);
  
  /* total number of cpus in this system (may exceed NR_CPUS) */
  extern unsigned int total_cpus;
  
  int smp_call_function_single(int cpuid, smp_call_func_t func, void *info,
  			     int wait);
  
  void on_each_cpu_cond_mask(smp_cond_func_t cond_func, smp_call_func_t func,
  			   void *info, bool wait, const struct cpumask *mask);
  
  int smp_call_function_single_async(int cpu, struct __call_single_data *csd);
  
  /*
   * Cpus stopping functions in panic. All have default weak definitions.
   * Architecture-dependent code may override them.
   */
  void panic_smp_self_stop(void);
  void nmi_panic_self_stop(struct pt_regs *regs);
  void crash_smp_send_stop(void);
  
  /*
   * Call a function on all processors
   */
  static inline void on_each_cpu(smp_call_func_t func, void *info, int wait)
  {
  	on_each_cpu_cond_mask(NULL, func, info, wait, cpu_online_mask);
  }
  
  /**
   * on_each_cpu_mask(): Run a function on processors specified by
   * cpumask, which may include the local processor.
   * @mask: The set of cpus to run on (only runs on online subset).
   * @func: The function to run. This must be fast and non-blocking.
   * @info: An arbitrary pointer to pass to the function.
   * @wait: If true, wait (atomically) until function has completed
   *        on other CPUs.
   *
   * If @wait is true, then returns once @func has returned.
   *
   * You must not call this function with disabled interrupts or from a
   * hardware interrupt handler or from a bottom half handler.  The
   * exception is that it may be used during early boot while
   * early_boot_irqs_disabled is set.
   */
  static inline void on_each_cpu_mask(const struct cpumask *mask,
  				    smp_call_func_t func, void *info, bool wait)
  {
  	on_each_cpu_cond_mask(NULL, func, info, wait, mask);
  }
  
  /*
   * Call a function on each processor for which the supplied function
   * cond_func returns a positive value. This may include the local
   * processor.  May be used during early boot while early_boot_irqs_disabled is
   * set. Use local_irq_save/restore() instead of local_irq_disable/enable().
   */
  static inline void on_each_cpu_cond(smp_cond_func_t cond_func,
  				    smp_call_func_t func, void *info, bool wait)
  {
  	on_each_cpu_cond_mask(cond_func, func, info, wait, cpu_online_mask);
  }
  
  #ifdef CONFIG_SMP
  
  #include <linux/preempt.h>
  #include <linux/compiler.h>
  #include <linux/thread_info.h>
  #include <asm/smp.h>
  
  /*
   * main cross-CPU interfaces, handles INIT, TLB flush, STOP, etc.
   * (defined in asm header):
   */
  
  /*
   * stops all CPUs but the current one:
   */
  extern void smp_send_stop(void);
  
  /*
   * sends a 'reschedule' event to another CPU:
   */
  extern void smp_send_reschedule(int cpu);
  
  
  /*
   * Prepare machine for booting other CPUs.
   */
  extern void smp_prepare_cpus(unsigned int max_cpus);
  
  /*
   * Bring a CPU up
   */
  extern int __cpu_up(unsigned int cpunum, struct task_struct *tidle);
  
  /*
   * Final polishing of CPUs
   */
  extern void smp_cpus_done(unsigned int max_cpus);
  
  /*
   * Call a function on all other processors
   */
  void smp_call_function(smp_call_func_t func, void *info, int wait);
  void smp_call_function_many(const struct cpumask *mask,
  			    smp_call_func_t func, void *info, bool wait);
  
  int smp_call_function_any(const struct cpumask *mask,
  			  smp_call_func_t func, void *info, int wait);
  
  void kick_all_cpus_sync(void);
  void wake_up_all_idle_cpus(void);
  
  /*
   * Generic and arch helpers
   */
  void __init call_function_init(void);
  void generic_smp_call_function_single_interrupt(void);
  #define generic_smp_call_function_interrupt \
  	generic_smp_call_function_single_interrupt
  
  /*
   * Mark the boot cpu "online" so that it can call console drivers in
   * printk() and can access its per-cpu storage.
   */
  void smp_prepare_boot_cpu(void);
  
  extern unsigned int setup_max_cpus;
  extern void __init setup_nr_cpu_ids(void);
  extern void __init smp_init(void);
  
  extern int __boot_cpu_id;
  
  static inline int get_boot_cpu_id(void)
  {
  	return __boot_cpu_id;
  }
  
  #else /* !SMP */
  
  static inline void smp_send_stop(void) { }
  
  /*
   *	These macros fold the SMP functionality into a single CPU system
   */
  #define raw_smp_processor_id()			0
  static inline void up_smp_call_function(smp_call_func_t func, void *info)
  {
  }
  #define smp_call_function(func, info, wait) \
  			(up_smp_call_function(func, info))
  
  static inline void smp_send_reschedule(int cpu) { }
  #define smp_prepare_boot_cpu()			do {} while (0)
  #define smp_call_function_many(mask, func, info, wait) \
  			(up_smp_call_function(func, info))
  static inline void call_function_init(void) { }
  
  static inline int
  smp_call_function_any(const struct cpumask *mask, smp_call_func_t func,
  		      void *info, int wait)
  {
  	return smp_call_function_single(0, func, info, wait);
  }
  
  static inline void kick_all_cpus_sync(void) {  }
  static inline void wake_up_all_idle_cpus(void) {  }
  
  #ifdef CONFIG_UP_LATE_INIT
  extern void __init up_late_init(void);
  static inline void smp_init(void) { up_late_init(); }
  #else
  static inline void smp_init(void) { }
  #endif
  
  static inline int get_boot_cpu_id(void)
  {
  	return 0;
  }
  
  #endif /* !SMP */
  
  /**
   * raw_processor_id() - get the current (unstable) CPU id
   *
   * For then you know what you are doing and need an unstable
   * CPU id.
   */
  
  /**
   * smp_processor_id() - get the current (stable) CPU id
   *
   * This is the normal accessor to the CPU id and should be used
   * whenever possible.
   *
   * The CPU id is stable when:
   *
   *  - IRQs are disabled;
   *  - preemption is disabled;
   *  - the task is CPU affine.
   *
   * When CONFIG_DEBUG_PREEMPT; we verify these assumption and WARN
   * when smp_processor_id() is used when the CPU id is not stable.
   */
  
  /*
   * Allow the architecture to differentiate between a stable and unstable read.
   * For example, x86 uses an IRQ-safe asm-volatile read for the unstable but a
   * regular asm read for the stable.
   */
  #ifndef __smp_processor_id
  #define __smp_processor_id(x) raw_smp_processor_id(x)
  #endif
  
  #ifdef CONFIG_DEBUG_PREEMPT
    extern unsigned int debug_smp_processor_id(void);
  # define smp_processor_id() debug_smp_processor_id()
  #else
  # define smp_processor_id() __smp_processor_id()
  #endif
  
  #define get_cpu()		({ preempt_disable(); __smp_processor_id(); })
  #define put_cpu()		preempt_enable()
  
  /*
   * Callback to arch code if there's nosmp or maxcpus=0 on the
   * boot command line:
   */
  extern void arch_disable_smp_support(void);
  
  extern void arch_thaw_secondary_cpus_begin(void);
  extern void arch_thaw_secondary_cpus_end(void);
  
  void smp_setup_processor_id(void);
  
  int smp_call_on_cpu(unsigned int cpu, int (*func)(void *), void *par,
  		    bool phys);
  
  /* SMP core functions */
  int smpcfd_prepare_cpu(unsigned int cpu);
  int smpcfd_dead_cpu(unsigned int cpu);
  int smpcfd_dying_cpu(unsigned int cpu);
  
  #endif /* __LINUX_SMP_H */
  