The following commit has been merged into the locking/core branch of tip: Commit-ID: e81859fe64ad42dccefe134d1696e0635f78d763 Gitweb: https://git.kernel.org/tip/e81859fe64ad42dccefe134d1696e0635f78d763 Author: John Stultz <jstultz@xxxxxxxxxx> AuthorDate: Mon, 08 Jul 2024 23:08:27 -07:00 Committer: Peter Zijlstra <peterz@xxxxxxxxxxxxx> CommitterDate: Tue, 09 Jul 2024 13:26:26 +02:00 locking/rwsem: Add __always_inline annotation to __down_write_common() and inlined callers Apparently despite it being marked inline, the compiler may not inline __down_write_common() which makes it difficult to identify the cause of lock contention, as the wchan of the blocked function will always be listed as __down_write_common(). So add __always_inline annotation to the common function (as well as the inlined helper callers) to force it to be inlined so a more useful blocking function will be listed (via wchan). This mirrors commit 92cc5d00a431 ("locking/rwsem: Add __always_inline annotation to __down_read_common() and inlined callers") which did the same for __down_read_common. I sort of worry that I'm playing wack-a-mole here, and talking with compiler people, they tell me inline means nothing, which makes me want to cry a little. So I'm wondering if we need to replace all the inlines with __always_inline, or remove them because either we mean something by it, or not. Fixes: c995e638ccbb ("locking/rwsem: Fold __down_{read,write}*()") Reported-by: Tim Murray <timmurray@xxxxxxxxxx> Signed-off-by: John Stultz <jstultz@xxxxxxxxxx> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> Acked-by: Waiman Long <longman@xxxxxxxxxx> Link: https://lkml.kernel.org/r/20240709060831.495366-1-jstultz@xxxxxxxxxx --- kernel/locking/rwsem.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/kernel/locking/rwsem.c b/kernel/locking/rwsem.c index c6d17ae..33cac79 100644 --- a/kernel/locking/rwsem.c +++ b/kernel/locking/rwsem.c @@ -1297,7 +1297,7 @@ static inline int __down_read_trylock(struct rw_semaphore *sem) /* * lock for writing */ -static inline int __down_write_common(struct rw_semaphore *sem, int state) +static __always_inline int __down_write_common(struct rw_semaphore *sem, int state) { int ret = 0; @@ -1310,12 +1310,12 @@ static inline int __down_write_common(struct rw_semaphore *sem, int state) return ret; } -static inline void __down_write(struct rw_semaphore *sem) +static __always_inline void __down_write(struct rw_semaphore *sem) { __down_write_common(sem, TASK_UNINTERRUPTIBLE); } -static inline int __down_write_killable(struct rw_semaphore *sem) +static __always_inline int __down_write_killable(struct rw_semaphore *sem) { return __down_write_common(sem, TASK_KILLABLE); }