From: John Stultz jstultz@google.com
commit 92cc5d00a431e96e5a49c0b97e5ad4fa7536bd4b upstream.
Apparently despite it being marked inline, the compiler may not inline __down_read_common() which makes it difficult to identify the cause of lock contention, as the blocked function in traceevents will always be listed as __down_read_common().
So this patch adds __always_inline annotation to the common function (as well as the inlined helper callers) to force it to be inlined so the blocking function will be listed (via Wchan) in traceevents.
Fixes: c995e638ccbb ("locking/rwsem: Fold __down_{read,write}*()") Reported-by: Tim Murray timmurray@google.com Signed-off-by: John Stultz jstultz@google.com Signed-off-by: Peter Zijlstra (Intel) peterz@infradead.org Reviewed-by: Waiman Long longman@redhat.com Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/20230503023351.2832796-1-jstultz@google.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- kernel/locking/rwsem.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)
--- a/kernel/locking/rwsem.c +++ b/kernel/locking/rwsem.c @@ -1251,7 +1251,7 @@ static struct rw_semaphore *rwsem_downgr /* * lock for reading */ -static inline int __down_read_common(struct rw_semaphore *sem, int state) +static __always_inline int __down_read_common(struct rw_semaphore *sem, int state) { int ret = 0; long count; @@ -1269,17 +1269,17 @@ out: return ret; }
-static inline void __down_read(struct rw_semaphore *sem) +static __always_inline void __down_read(struct rw_semaphore *sem) { __down_read_common(sem, TASK_UNINTERRUPTIBLE); }
-static inline int __down_read_interruptible(struct rw_semaphore *sem) +static __always_inline int __down_read_interruptible(struct rw_semaphore *sem) { return __down_read_common(sem, TASK_INTERRUPTIBLE); }
-static inline int __down_read_killable(struct rw_semaphore *sem) +static __always_inline int __down_read_killable(struct rw_semaphore *sem) { return __down_read_common(sem, TASK_KILLABLE); }