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locking/percpu-rwsem: Fold __percpu_up_read()

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Now that __percpu_up_read() is only ever used from percpu_up_read()
merge them, it's a small function.

Signed-off-by: Davidlohr Bueso <dave@stgolabs.net>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Acked-by: Waiman Long <longman@redhat.com>
Link: https://lkml.kernel.org/r/20200131151540.212415454@infradead.org
This commit is contained in:
Davidlohr Bueso
2019-11-18 15:19:35 -08:00
committed by Ingo Molnar
parent bcba67cd80
commit ac8dec4209
3 changed files with 16 additions and 19 deletions
Download Patch File Download Diff File Expand all files Collapse all files

19
include/linux/percpu-rwsem.h
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@@ -43,7 +43,6 @@ is_static struct percpu_rw_semaphore name = { \
__DEFINE_PERCPU_RWSEM(name, static) __DEFINE_PERCPU_RWSEM(name, static)
extern bool __percpu_down_read(struct percpu_rw_semaphore *, bool); extern bool __percpu_down_read(struct percpu_rw_semaphore *, bool);
extern void __percpu_up_read(struct percpu_rw_semaphore *);
static inline void percpu_down_read(struct percpu_rw_semaphore *sem) static inline void percpu_down_read(struct percpu_rw_semaphore *sem)
{ {
@@ -103,10 +102,22 @@ static inline void percpu_up_read(struct percpu_rw_semaphore *sem)
/* /*
* Same as in percpu_down_read(). * Same as in percpu_down_read().
*/ */
if (likely(rcu_sync_is_idle(&sem->rss))) if (likely(rcu_sync_is_idle(&sem->rss))) {
__this_cpu_dec(*sem->read_count); __this_cpu_dec(*sem->read_count);
else } else {
__percpu_up_read(sem); /* Unconditional memory barrier */ /*
* slowpath; reader will only ever wake a single blocked
* writer.
*/
smp_mb(); /* B matches C */
/*
* In other words, if they see our decrement (presumably to
* aggregate zero, as that is the only time it matters) they
* will also see our critical section.
*/
__this_cpu_dec(*sem->read_count);
rcuwait_wake_up(&sem->writer);
}
preempt_enable(); preempt_enable();
} }

1
kernel/exit.c
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@@ -258,6 +258,7 @@ void rcuwait_wake_up(struct rcuwait *w)
wake_up_process(task); wake_up_process(task);
rcu_read_unlock(); rcu_read_unlock();
} }
EXPORT_SYMBOL_GPL(rcuwait_wake_up);
/* /*
* Determine if a process group is "orphaned", according to the POSIX * Determine if a process group is "orphaned", according to the POSIX

15
kernel/locking/percpu-rwsem.c
View File

@@ -177,21 +177,6 @@ bool __percpu_down_read(struct percpu_rw_semaphore *sem, bool try)
} }
EXPORT_SYMBOL_GPL(__percpu_down_read); EXPORT_SYMBOL_GPL(__percpu_down_read);
void __percpu_up_read(struct percpu_rw_semaphore *sem)
{
smp_mb(); /* B matches C */
/*
* In other words, if they see our decrement (presumably to aggregate
* zero, as that is the only time it matters) they will also see our
* critical section.
*/
__this_cpu_dec(*sem->read_count);
/* Prod writer to re-evaluate readers_active_check() */
rcuwait_wake_up(&sem->writer);
}
EXPORT_SYMBOL_GPL(__percpu_up_read);
#define per_cpu_sum(var) \ #define per_cpu_sum(var) \
({ \ ({ \
typeof(var) __sum = 0; \ typeof(var) __sum = 0; \