linux-kernel - [PATCH 2/2] regulator: core: skip nesting lock for -EDEADLK

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Message-Id: <89a905854995cf662a122792d8d0c781e39ea7da.1692475736.git.mirq-linux@rere.qmqm.pl>
Date:   Sat, 19 Aug 2023 22:15:43 +0200
From:   Michał Mirosław <mirq-linux@...e.qmqm.pl>
To:     Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>
Cc:     linux-kernel@...r.kernel.org
Subject: [PATCH 2/2] regulator: core: skip nesting lock for -EDEADLK

When ww_mutex_lock() returns -EDEADLK the nesting mutex-protected
section becomes a no-op. Return early and avoid the extra lock.

Signed-off-by: Michał Mirosław <mirq-linux@...e.qmqm.pl>
---
 drivers/regulator/core.c | 19 +++++++++----------
 1 file changed, 9 insertions(+), 10 deletions(-)

diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index 215b721e5cd4..921c7039baa3 100644
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -145,18 +145,17 @@ static inline int regulator_lock_nested(struct regulator_dev *rdev,
 
 	mutex_lock(&regulator_nesting_mutex);
 
-	if (!ww_mutex_trylock(&rdev->mutex, ww_ctx)) {
-		if (rdev->mutex_owner != current) {
-			mutex_unlock(&regulator_nesting_mutex);
-			ret = ww_mutex_lock(&rdev->mutex, ww_ctx);
-			mutex_lock(&regulator_nesting_mutex);
-		}
+	if (!ww_mutex_trylock(&rdev->mutex, ww_ctx) &&
+	    rdev->mutex_owner != current) {
+		mutex_unlock(&regulator_nesting_mutex);
+		ret = ww_mutex_lock(&rdev->mutex, ww_ctx);
+		if (ret == -EDEADLK)
+			return ret;
+		mutex_lock(&regulator_nesting_mutex);
 	}
 
-	if (ret != -EDEADLK) {
-		rdev->ref_cnt++;
-		rdev->mutex_owner = current;
-	}
+	rdev->ref_cnt++;
+	rdev->mutex_owner = current;
 
 	mutex_unlock(&regulator_nesting_mutex);
 
-- 
2.39.2