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	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 /* 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);
 unsigned long get_state_synchronize_srcu(struct srcu_struct *ssp);
 unsigned long start_poll_synchronize_srcu(struct srcu_struct *ssp);
 bool poll_state_synchronize_srcu(struct srcu_struct *ssp, unsigned long cookie);
 
 #ifdef CONFIG_SRCU
 void srcu_init(void);
 #else /* #ifdef CONFIG_SRCU */
 static inline void srcu_init(void) { }
 #endif /* #else #ifdef CONFIG_SRCU */
 
 #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), __UNIQUE_ID(rcu), \
                 (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

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