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| author | Paul E. McKenney <paul.mckenney@linaro.org> | 2011-08-01 06:22:11 -0700 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2011-09-28 21:38:35 -0700 |
| commit | 6206ab9bab620fc0fbbed30ce20d145b0b3d1840 (patch) | |
| tree | b57912ba9fff6f2deba89c0178d3122bbd1fda6e | |
| parent | 6846c0c54074d47927c90eab4a805115e1ae3292 (diff) | |
| download | linux-stable-6206ab9bab620fc0fbbed30ce20d145b0b3d1840.tar.gz linux-stable-6206ab9bab620fc0fbbed30ce20d145b0b3d1840.tar.bz2 linux-stable-6206ab9bab620fc0fbbed30ce20d145b0b3d1840.zip | |
rcu: Move __rcu_read_unlock()'s barrier() within if-statement
We only need to constrain the compiler if we are actually exiting
the top-level RCU read-side critical section. This commit therefore
moves the first barrier() cal in __rcu_read_unlock() to inside the
"if" statement, thus avoiding needless register flushes for inner
rcu_read_unlock() calls.
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
| -rw-r--r-- | include/linux/rcupdate.h | 14 | ||||
| -rw-r--r-- | kernel/rcutree_plugin.h | 2 |
2 files changed, 3 insertions, 13 deletions
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index af186e260c43..2cf4226ade7e 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -134,16 +134,6 @@ extern void call_rcu_sched(struct rcu_head *head, extern void synchronize_sched(void); -static inline void __rcu_read_lock_bh(void) -{ - local_bh_disable(); -} - -static inline void __rcu_read_unlock_bh(void) -{ - local_bh_enable(); -} - #ifdef CONFIG_PREEMPT_RCU extern void __rcu_read_lock(void); @@ -686,7 +676,7 @@ static inline void rcu_read_unlock(void) */ static inline void rcu_read_lock_bh(void) { - __rcu_read_lock_bh(); + local_bh_disable(); __acquire(RCU_BH); rcu_read_acquire_bh(); } @@ -700,7 +690,7 @@ static inline void rcu_read_unlock_bh(void) { rcu_read_release_bh(); __release(RCU_BH); - __rcu_read_unlock_bh(); + local_bh_enable(); } /** diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h index 4bac5a29fb69..ed70f6bf4c31 100644 --- a/kernel/rcutree_plugin.h +++ b/kernel/rcutree_plugin.h @@ -415,10 +415,10 @@ void __rcu_read_unlock(void) { struct task_struct *t = current; - barrier(); /* needed if we ever invoke rcu_read_unlock in rcutree.c */ if (t->rcu_read_lock_nesting != 1) --t->rcu_read_lock_nesting; else { + barrier(); /* critical section before exit code. */ t->rcu_read_lock_nesting = INT_MIN; barrier(); /* assign before ->rcu_read_unlock_special load */ if (unlikely(ACCESS_ONCE(t->rcu_read_unlock_special))) |