linux-kernel - [tip: locking/urgent] locking/ww_mutex: Fix acquire/release imbalance in ww_acquire_init()/ww_acquire

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Date:   Wed, 17 Mar 2021 12:38:22 -0000
From:   "tip-bot2 for Waiman Long" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Waiman Long <longman@...hat.com>, Ingo Molnar <mingo@...nel.org>,
        x86@...nel.org, linux-kernel@...r.kernel.org
Subject: [tip: locking/urgent] locking/ww_mutex: Fix acquire/release imbalance
 in ww_acquire_init()/ww_acquire_fini()

The following commit has been merged into the locking/urgent branch of tip:

Commit-ID:     bee645788e07eea63055d261d2884ea45c2ba857
Gitweb:        https://git.kernel.org/tip/bee645788e07eea63055d261d2884ea45c2ba857
Author:        Waiman Long <longman@...hat.com>
AuthorDate:    Tue, 16 Mar 2021 11:31:17 -04:00
Committer:     Ingo Molnar <mingo@...nel.org>
CommitterDate: Wed, 17 Mar 2021 09:56:45 +01:00

locking/ww_mutex: Fix acquire/release imbalance in ww_acquire_init()/ww_acquire_fini()

In ww_acquire_init(), mutex_acquire() is gated by CONFIG_DEBUG_LOCK_ALLOC.
The dep_map in the ww_acquire_ctx structure is also gated by the
same config. However mutex_release() in ww_acquire_fini() is gated by
CONFIG_DEBUG_MUTEXES. It is possible to set CONFIG_DEBUG_MUTEXES without
setting CONFIG_DEBUG_LOCK_ALLOC though it is an unlikely configuration.
That may cause a compilation error as dep_map isn't defined in this
case. Fix this potential problem by enclosing mutex_release() inside
CONFIG_DEBUG_LOCK_ALLOC.

Signed-off-by: Waiman Long <longman@...hat.com>
Signed-off-by: Ingo Molnar <mingo@...nel.org>
Link: https://lore.kernel.org/r/20210316153119.13802-3-longman@redhat.com
---
 include/linux/ww_mutex.h | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/include/linux/ww_mutex.h b/include/linux/ww_mutex.h
index 850424e..6ecf2a0 100644
--- a/include/linux/ww_mutex.h
+++ b/include/linux/ww_mutex.h
@@ -173,9 +173,10 @@ static inline void ww_acquire_done(struct ww_acquire_ctx *ctx)
  */
 static inline void ww_acquire_fini(struct ww_acquire_ctx *ctx)
 {
-#ifdef CONFIG_DEBUG_MUTEXES
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
 	mutex_release(&ctx->dep_map, _THIS_IP_);
-
+#endif
+#ifdef CONFIG_DEBUG_MUTEXES
 	DEBUG_LOCKS_WARN_ON(ctx->acquired);
 	if (!IS_ENABLED(CONFIG_PROVE_LOCKING))
 		/*