linux-kernel - [PATCH] lockref: add a __cond_lock annotation for lockref_put_or

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Message-ID: <20251124135849.902631-1-hch@lst.de>
Date: Mon, 24 Nov 2025 14:58:21 +0100
From: Christoph Hellwig <hch@....de>
To: akpm@...ux-foundation.org
Cc: torvalds@...ux-foundation.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH] lockref: add a __cond_lock annotation for lockref_put_or_lock

Add a cond_lock annotation for lockref_put_or_lock to make sparse
happy with using it.  Note that for this the return value has to be
double-inverted as the return value convention of lockref_put_or_lock
is inverted compared to _trylock conventions expected by __cond_lock,
as lockref_put_or_lock returns true when it did not need to take the
lock.

Signed-off-by: Christoph Hellwig <hch@....de>
---

I still prefer the version with the _-prefix, but this works as well and
Linus like it.  So let's go with it.

 include/linux/lockref.h | 2 ++
 lib/lockref.c           | 1 +
 2 files changed, 3 insertions(+)

diff --git a/include/linux/lockref.h b/include/linux/lockref.h
index 676721ee878d..815d871fadfc 100644
--- a/include/linux/lockref.h
+++ b/include/linux/lockref.h
@@ -50,6 +50,8 @@ void lockref_get(struct lockref *lockref);
 int lockref_put_return(struct lockref *lockref);
 bool lockref_get_not_zero(struct lockref *lockref);
 bool lockref_put_or_lock(struct lockref *lockref);
+#define lockref_put_or_lock(_lockref) \
+	(!__cond_lock((_lockref)->lock, !lockref_put_or_lock(_lockref)))
 
 void lockref_mark_dead(struct lockref *lockref);
 bool lockref_get_not_dead(struct lockref *lockref);
diff --git a/lib/lockref.c b/lib/lockref.c
index 5d8e3ef3860e..9210fc6ae714 100644
--- a/lib/lockref.c
+++ b/lib/lockref.c
@@ -105,6 +105,7 @@ EXPORT_SYMBOL(lockref_put_return);
  * @lockref: pointer to lockref structure
  * Return: 1 if count updated successfully or 0 if count <= 1 and lock taken
  */
+#undef lockref_put_or_lock
 bool lockref_put_or_lock(struct lockref *lockref)
 {
 	CMPXCHG_LOOP(
-- 
2.47.3