git.ipfire.org Git - thirdparty/kernel/stable-queue.git/blob

   1 From 92cc5d00a431e96e5a49c0b97e5ad4fa7536bd4b Mon Sep 17 00:00:00 2001
   2 From: John Stultz <jstultz@google.com>
   3 Date: Wed, 3 May 2023 02:33:51 +0000
   4 Subject: locking/rwsem: Add __always_inline annotation to __down_read_common() and inlined callers
   5
   6 From: John Stultz <jstultz@google.com>
   7
   8 commit 92cc5d00a431e96e5a49c0b97e5ad4fa7536bd4b upstream.
   9
  10 Apparently despite it being marked inline, the compiler
  11 may not inline __down_read_common() which makes it difficult
  12 to identify the cause of lock contention, as the blocked
  13 function in traceevents will always be listed as
  14 __down_read_common().
  15
  16 So this patch adds __always_inline annotation to the common
  17 function (as well as the inlined helper callers) to force it to
  18 be inlined so the blocking function will be listed (via Wchan)
  19 in traceevents.
  20
  21 Fixes: c995e638ccbb ("locking/rwsem: Fold __down_{read,write}*()")
  22 Reported-by: Tim Murray <timmurray@google.com>
  23 Signed-off-by: John Stultz <jstultz@google.com>
  24 Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
  25 Reviewed-by: Waiman Long <longman@redhat.com>
  26 Cc: stable@vger.kernel.org
  27 Link: https://lkml.kernel.org/r/20230503023351.2832796-1-jstultz@google.com
  28 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  29 ---
  30  kernel/locking/rwsem.c |    8 ++++----
  31  1 file changed, 4 insertions(+), 4 deletions(-)
  32
  33 --- a/kernel/locking/rwsem.c
  34 +++ b/kernel/locking/rwsem.c
  35 @@ -1251,7 +1251,7 @@ static struct rw_semaphore *rwsem_downgr
  36  /*
  37   * lock for reading
  38   */
  39 -static inline int __down_read_common(struct rw_semaphore *sem, int state)
  40 +static __always_inline int __down_read_common(struct rw_semaphore *sem, int state)
  41  {
  42         int ret = 0;
  43         long count;
  44 @@ -1269,17 +1269,17 @@ out:
  45         return ret;
  46  }
  47
  48 -static inline void __down_read(struct rw_semaphore *sem)
  49 +static __always_inline void __down_read(struct rw_semaphore *sem)
  50  {
  51         __down_read_common(sem, TASK_UNINTERRUPTIBLE);
  52  }
  53
  54 -static inline int __down_read_interruptible(struct rw_semaphore *sem)
  55 +static __always_inline int __down_read_interruptible(struct rw_semaphore *sem)
  56  {
  57         return __down_read_common(sem, TASK_INTERRUPTIBLE);
  58  }
  59
  60 -static inline int __down_read_killable(struct rw_semaphore *sem)
  61 +static __always_inline int __down_read_killable(struct rw_semaphore *sem)
  62  {
  63         return __down_read_common(sem, TASK_KILLABLE);
  64  }