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rcu: Move rnp->lock wrappers for SRCU use
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This commit moves the now-generic rnp->lock wrapper macros from
kernel/rcu/tree.h to kernel/rcu/rcu.h, thus allowing SRCU to use them.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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Paul E. McKenney committed Jun 9, 2017
1 parent bf32c76 commit 83d40bd
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Showing 2 changed files with 53 additions and 53 deletions.
53 changes: 53 additions & 0 deletions kernel/rcu/rcu.h
Original file line number Diff line number Diff line change
Expand Up @@ -303,6 +303,59 @@ static inline void rcu_init_levelspread(int *levelspread, const int *levelcnt)
cpu <= rnp->grphi; \
cpu = cpumask_next((cpu), cpu_possible_mask))

/*
* Wrappers for the rcu_node::lock acquire and release.
*
* Because the rcu_nodes form a tree, the tree traversal locking will observe
* different lock values, this in turn means that an UNLOCK of one level
* followed by a LOCK of another level does not imply a full memory barrier;
* and most importantly transitivity is lost.
*
* In order to restore full ordering between tree levels, augment the regular
* lock acquire functions with smp_mb__after_unlock_lock().
*
* As ->lock of struct rcu_node is a __private field, therefore one should use
* these wrappers rather than directly call raw_spin_{lock,unlock}* on ->lock.
*/
#define raw_spin_lock_rcu_node(p) \
do { \
raw_spin_lock(&ACCESS_PRIVATE(p, lock)); \
smp_mb__after_unlock_lock(); \
} while (0)

#define raw_spin_unlock_rcu_node(p) raw_spin_unlock(&ACCESS_PRIVATE(p, lock))

#define raw_spin_lock_irq_rcu_node(p) \
do { \
raw_spin_lock_irq(&ACCESS_PRIVATE(p, lock)); \
smp_mb__after_unlock_lock(); \
} while (0)

#define raw_spin_unlock_irq_rcu_node(p) \
raw_spin_unlock_irq(&ACCESS_PRIVATE(p, lock))

#define raw_spin_lock_irqsave_rcu_node(rnp, flags) \
do { \
typecheck(unsigned long, flags); \
raw_spin_lock_irqsave(&ACCESS_PRIVATE(rnp, lock), flags); \
smp_mb__after_unlock_lock(); \
} while (0)

#define raw_spin_unlock_irqrestore_rcu_node(rnp, flags) \
do { \
typecheck(unsigned long, flags); \
raw_spin_unlock_irqrestore(&ACCESS_PRIVATE(rnp, lock), flags); \
} while (0)

#define raw_spin_trylock_rcu_node(p) \
({ \
bool ___locked = raw_spin_trylock(&ACCESS_PRIVATE(p, lock)); \
\
if (___locked) \
smp_mb__after_unlock_lock(); \
___locked; \
})

#endif /* #if defined(SRCU) || !defined(TINY_RCU) */

#ifdef CONFIG_TINY_RCU
Expand Down
53 changes: 0 additions & 53 deletions kernel/rcu/tree.h
Original file line number Diff line number Diff line change
Expand Up @@ -565,56 +565,3 @@ static inline void rcu_nocb_q_lengths(struct rcu_data *rdp, long *ql, long *qll)
#endif /* #else #ifdef CONFIG_RCU_NOCB_CPU */
}
#endif /* #ifdef CONFIG_RCU_TRACE */

/*
* Wrappers for the rcu_node::lock acquire and release.
*
* Because the rcu_nodes form a tree, the tree traversal locking will observe
* different lock values, this in turn means that an UNLOCK of one level
* followed by a LOCK of another level does not imply a full memory barrier;
* and most importantly transitivity is lost.
*
* In order to restore full ordering between tree levels, augment the regular
* lock acquire functions with smp_mb__after_unlock_lock().
*
* As ->lock of struct rcu_node is a __private field, therefore one should use
* these wrappers rather than directly call raw_spin_{lock,unlock}* on ->lock.
*/
#define raw_spin_lock_rcu_node(p) \
do { \
raw_spin_lock(&ACCESS_PRIVATE(p, lock)); \
smp_mb__after_unlock_lock(); \
} while (0)

#define raw_spin_unlock_rcu_node(p) raw_spin_unlock(&ACCESS_PRIVATE(p, lock))

#define raw_spin_lock_irq_rcu_node(p) \
do { \
raw_spin_lock_irq(&ACCESS_PRIVATE(p, lock)); \
smp_mb__after_unlock_lock(); \
} while (0)

#define raw_spin_unlock_irq_rcu_node(p) \
raw_spin_unlock_irq(&ACCESS_PRIVATE(p, lock))

#define raw_spin_lock_irqsave_rcu_node(rnp, flags) \
do { \
typecheck(unsigned long, flags); \
raw_spin_lock_irqsave(&ACCESS_PRIVATE(rnp, lock), flags); \
smp_mb__after_unlock_lock(); \
} while (0)

#define raw_spin_unlock_irqrestore_rcu_node(rnp, flags) \
do { \
typecheck(unsigned long, flags); \
raw_spin_unlock_irqrestore(&ACCESS_PRIVATE(rnp, lock), flags); \
} while (0)

#define raw_spin_trylock_rcu_node(p) \
({ \
bool ___locked = raw_spin_trylock(&ACCESS_PRIVATE(p, lock)); \
\
if (___locked) \
smp_mb__after_unlock_lock(); \
___locked; \
})

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