/* SPDX-License-Identifier: GPL-2.0+ */

  /*
   * Sleepable Read-Copy Update mechanism for mutual exclusion
   *

   * Copyright (C) IBM Corporation, 2006

   * Copyright (C) Fujitsu, 2012

   *

   * Author: Paul McKenney <paulmck@linux.ibm.com>

   *	   Lai Jiangshan <laijs@cn.fujitsu.com>

   *
   * For detailed explanation of Read-Copy Update mechanism see -

   *		Documentation/RCU/ *.txt

   *
   */

  #ifndef _LINUX_SRCU_H
  #define _LINUX_SRCU_H

  #include <linux/mutex.h>

  #include <linux/rcupdate.h>

  #include <linux/workqueue.h>

  #include <linux/rcu_segcblist.h>

  struct srcu_struct;

  #ifdef CONFIG_DEBUG_LOCK_ALLOC

  int __init_srcu_struct(struct srcu_struct *ssp, const char *name,

  		       struct lock_class_key *key);

  #define init_srcu_struct(ssp) \

  ({ \
  	static struct lock_class_key __srcu_key; \
  	\

  	__init_srcu_struct((ssp), #ssp, &__srcu_key); \

  })

  #define __SRCU_DEP_MAP_INIT(srcu_name)	.dep_map = { .name = #srcu_name },

  #else /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */

  int init_srcu_struct(struct srcu_struct *ssp);

  #define __SRCU_DEP_MAP_INIT(srcu_name)

  #endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */

  #ifdef CONFIG_TINY_SRCU
  #include <linux/srcutiny.h>
  #elif defined(CONFIG_TREE_SRCU)
  #include <linux/srcutree.h>

  #elif defined(CONFIG_SRCU)

  #error "Unknown SRCU implementation specified to kernel configuration"

  #else

  /* Dummy definition for things like notifiers.  Actual use gets link error. */
  struct srcu_struct { };

  #endif

  void call_srcu(struct srcu_struct *ssp, struct rcu_head *head,

  		void (*func)(struct rcu_head *head));

  void cleanup_srcu_struct(struct srcu_struct *ssp);

  int __srcu_read_lock(struct srcu_struct *ssp) __acquires(ssp);
  void __srcu_read_unlock(struct srcu_struct *ssp, int idx) __releases(ssp);
  void synchronize_srcu(struct srcu_struct *ssp);

  #ifdef CONFIG_DEBUG_LOCK_ALLOC
  
  /**
   * srcu_read_lock_held - might we be in SRCU read-side critical section?

   * @ssp: The srcu_struct structure to check

   *

   * If CONFIG_DEBUG_LOCK_ALLOC is selected, returns nonzero iff in an SRCU
   * read-side critical section.  In absence of CONFIG_DEBUG_LOCK_ALLOC,

   * this assumes we are in an SRCU read-side critical section unless it can
   * prove otherwise.

   *

   * Checks debug_lockdep_rcu_enabled() to prevent false positives during boot
   * and while lockdep is disabled.
   *

   * Note that SRCU is based on its own statemachine and it doesn't
   * relies on normal RCU, it can be called from the CPU which
   * is in the idle loop from an RCU point of view or offline.

   */

  static inline int srcu_read_lock_held(const struct srcu_struct *ssp)

  {

  	if (!debug_lockdep_rcu_enabled())

  		return 1;

  	return lock_is_held(&ssp->dep_map);

  }
  
  #else /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */

  static inline int srcu_read_lock_held(const struct srcu_struct *ssp)

  {
  	return 1;
  }
  
  #endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */
  
  /**

   * srcu_dereference_check - fetch SRCU-protected pointer for later dereferencing
   * @p: the pointer to fetch and protect for later dereferencing

   * @ssp: pointer to the srcu_struct, which is used to check that we

   *	really are in an SRCU read-side critical section.
   * @c: condition to check for update-side use

   *

   * If PROVE_RCU is enabled, invoking this outside of an RCU read-side
   * critical section will result in an RCU-lockdep splat, unless @c evaluates
   * to 1.  The @c argument will normally be a logical expression containing
   * lockdep_is_held() calls.

   */

  #define srcu_dereference_check(p, ssp, c) \
  	__rcu_dereference_check((p), (c) || srcu_read_lock_held(ssp), __rcu)

  
  /**
   * srcu_dereference - fetch SRCU-protected pointer for later dereferencing
   * @p: the pointer to fetch and protect for later dereferencing

   * @ssp: pointer to the srcu_struct, which is used to check that we

   *	really are in an SRCU read-side critical section.
   *
   * Makes rcu_dereference_check() do the dirty work.  If PROVE_RCU
   * is enabled, invoking this outside of an RCU read-side critical
   * section will result in an RCU-lockdep splat.
   */

  #define srcu_dereference(p, ssp) srcu_dereference_check((p), (ssp), 0)

  
  /**

   * srcu_dereference_notrace - no tracing and no lockdep calls from here

   * @p: the pointer to fetch and protect for later dereferencing

   * @ssp: pointer to the srcu_struct, which is used to check that we

   *	really are in an SRCU read-side critical section.

   */

  #define srcu_dereference_notrace(p, ssp) srcu_dereference_check((p), (ssp), 1)

  
  /**

   * srcu_read_lock - register a new reader for an SRCU-protected structure.

   * @ssp: srcu_struct in which to register the new reader.

   *
   * Enter an SRCU read-side critical section.  Note that SRCU read-side

   * critical sections may be nested.  However, it is illegal to
   * call anything that waits on an SRCU grace period for the same
   * srcu_struct, whether directly or indirectly.  Please note that
   * one way to indirectly wait on an SRCU grace period is to acquire
   * a mutex that is held elsewhere while calling synchronize_srcu() or
   * synchronize_srcu_expedited().

   *
   * Note that srcu_read_lock() and the matching srcu_read_unlock() must
   * occur in the same context, for example, it is illegal to invoke
   * srcu_read_unlock() in an irq handler if the matching srcu_read_lock()
   * was invoked in process context.

   */

  static inline int srcu_read_lock(struct srcu_struct *ssp) __acquires(ssp)

  {

  	int retval;

  	retval = __srcu_read_lock(ssp);
  	rcu_lock_acquire(&(ssp)->dep_map);

  	return retval;
  }

  /* Used by tracing, cannot be traced and cannot invoke lockdep. */
  static inline notrace int

  srcu_read_lock_notrace(struct srcu_struct *ssp) __acquires(ssp)

  {
  	int retval;

  	retval = __srcu_read_lock(ssp);

  	return retval;
  }

  /**
   * srcu_read_unlock - unregister a old reader from an SRCU-protected structure.

   * @ssp: srcu_struct in which to unregister the old reader.

   * @idx: return value from corresponding srcu_read_lock().
   *
   * Exit an SRCU read-side critical section.
   */

  static inline void srcu_read_unlock(struct srcu_struct *ssp, int idx)
  	__releases(ssp)

  {

  	WARN_ON_ONCE(idx & ~0x1);

  	rcu_lock_release(&(ssp)->dep_map);
  	__srcu_read_unlock(ssp, idx);

  }

  /* Used by tracing, cannot be traced and cannot call lockdep. */
  static inline notrace void

  srcu_read_unlock_notrace(struct srcu_struct *ssp, int idx) __releases(ssp)

  {

  	__srcu_read_unlock(ssp, idx);

  }

  /**
   * smp_mb__after_srcu_read_unlock - ensure full ordering after srcu_read_unlock
   *
   * Converts the preceding srcu_read_unlock into a two-way memory barrier.
   *
   * Call this after srcu_read_unlock, to guarantee that all memory operations
   * that occur after smp_mb__after_srcu_read_unlock will appear to happen after
   * the preceding srcu_read_unlock.
   */
  static inline void smp_mb__after_srcu_read_unlock(void)
  {
  	/* __srcu_read_unlock has smp_mb() internally so nothing to do here. */
  }

  #endif