The following commit has been merged into the locking/core branch of tip:
Commit-ID: ac8dec420970f5cbaf2f6eda39153a60ec5b257b
Gitweb: https://git.kernel.org/tip/ac8dec420970f5cbaf2f6eda39153a60ec5b257b
Author: Davidlohr Bueso <dave@xxxxxxxxxxxx>
AuthorDate: Mon, 18 Nov 2019 15:19:35 -08:00
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitterDate: Tue, 11 Feb 2020 13:10:58 +01:00
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@xxxxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Acked-by: Will Deacon <will@xxxxxxxxxx>
Acked-by: Waiman Long <longman@xxxxxxxxxx>
Link: https://lkml.kernel.org/r/20200131151540.212415454@xxxxxxxxxxxxx
---
include/linux/percpu-rwsem.h | 19 +++++++++++++++----
kernel/exit.c | 1 +
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 f5ecf6a..5e033fe 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 2833ffb..f64a8f9 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 a136677..8048a9a 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; \
|