Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Sat, 19 Aug 2023 22:15:43 +0200
Message-Id: <89a905854995cf662a122792d8d0c781e39ea7da.1692475736.git.mirq-linux@rere.qmqm.pl>
In-Reply-To: <0e37d1f09718a6ab9204b367ff528ab02df25ac7.1692475736.git.mirq-linux@rere.qmqm.pl>
References: <0e37d1f09718a6ab9204b367ff528ab02df25ac7.1692475736.git.mirq-linux@rere.qmqm.pl>
Subject: [PATCH 2/2] regulator: core: skip nesting lock for -EDEADLK
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
From:   =?UTF-8?q?Micha=C5=82=20Miros=C5=82aw?= <mirq-linux@rere.qmqm.pl>
To:     Liam Girdwood <lgirdwood@gmail.com>,
        Mark Brown <broonie@kernel.org>
Cc:     linux-kernel@vger.kernel.org
Precedence: bulk

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@rere.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