From 92cc5d00a431e96e5a49c0b97e5ad4fa7536bd4b Mon Sep 17 00:00:00 2001
From: John Stultz <jstultz@google.com>
Date: Wed, 3 May 2023 02:33:51 +0000
Subject: [PATCH] locking/rwsem: Add __always_inline annotation to
 __down_read_common() and inlined callers
Git-commit: 92cc5d00a431e96e5a49c0b97e5ad4fa7536bd4b
Patch-mainline: v6.4-rc2
References: git-fixes
 
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: Jiri Wiesner <jwiesner@suse.de>
---
 kernel/locking/rwsem.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)
 
diff --git a/kernel/locking/rwsem.c b/kernel/locking/rwsem.c
index acb5a50309a1..9eabd585ce7a 100644
--- a/kernel/locking/rwsem.c
+++ b/kernel/locking/rwsem.c
@@ -1240,7 +1240,7 @@ static struct rw_semaphore *rwsem_downgrade_wake(struct rw_semaphore *sem)
 /*
  * 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;
@@ -1258,17 +1258,17 @@ static inline int __down_read_common(struct rw_semaphore *sem, int state)
 	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);
 }
-- 
2.35.3