diff options
| author | Davidlohr Bueso <dave@stgolabs.net> | 2019-11-18 15:19:35 -0800 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2020-02-11 13:10:58 +0100 |
| commit | ac8dec420970f5cbaf2f6eda39153a60ec5b257b (patch) | |
| tree | 5f46d367fbc18ec5b7e2d2b9a9701324984a34d7 | |
| parent | bcba67cd806800fa8e973ac49dbc7d2d8fb3e55e (diff) | |
locking/percpu-rwsem: Fold __percpu_up_read()
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
| -rw-r--r-- | include/linux/percpu-rwsem.h | 19 | ||||
| -rw-r--r-- | kernel/exit.c | 1 | ||||
| -rw-r--r-- | kernel/locking/percpu-rwsem.c | 15 |
3 files changed, 16 insertions, 19 deletions
diff --git a/include/linux/percpu-rwsem.h b/include/linux/percpu-rwsem.h index f5ecf6a8a1dd..5e033fe1ff4e 100644 --- a/include/linux/percpu-rwsem.h +++ b/include/linux/percpu-rwsem.h @@ -43,7 +43,6 @@ is_static struct percpu_rw_semaphore name = { \ __DEFINE_PERCPU_RWSEM(name, static) 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) { @@ -103,10 +102,22 @@ static inline void percpu_up_read(struct percpu_rw_semaphore *sem) /* * 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); - else - __percpu_up_read(sem); /* Unconditional memory barrier */ + } else { + /* + * 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(); } diff --git a/kernel/exit.c b/kernel/exit.c index 2833ffb0c211..f64a8f9d412a 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -258,6 +258,7 @@ void rcuwait_wake_up(struct rcuwait *w) wake_up_process(task); rcu_read_unlock(); } +EXPORT_SYMBOL_GPL(rcuwait_wake_up); /* * Determine if a process group is "orphaned", according to the POSIX diff --git a/kernel/locking/percpu-rwsem.c b/kernel/locking/percpu-rwsem.c index a136677543b4..8048a9a255d5 100644 --- a/kernel/locking/percpu-rwsem.c +++ b/kernel/locking/percpu-rwsem.c @@ -177,21 +177,6 @@ bool __percpu_down_read(struct percpu_rw_semaphore *sem, bool try) } 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) \ ({ \ typeof(var) __sum = 0; \ |