linux-kernel - [PATCH 5.1 386/405] regulator: pv88080: Fix notifier mutex lock warning

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Message-Id: <20190530030600.220899537@linuxfoundation.org>
Date:   Wed, 29 May 2019 20:06:24 -0700
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Adam Thomson <Adam.Thomson.Opensource@...semi.com>,
        Steve Twiss <stwiss.opensource@...semi.com>,
        Mark Brown <broonie@...nel.org>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.1 386/405] regulator: pv88080: Fix notifier mutex lock warning

[ Upstream commit 1867af94cfdf37fc70fe67b3d522e78352800196 ]

The mutex for the regulator_dev must be controlled by the caller of
the regulator_notifier_call_chain(), as described in the comment
for that function.

Failure to mutex lock and unlock surrounding the notifier call results
in a kernel WARN_ON_ONCE() which will dump a backtrace for the
regulator_notifier_call_chain() when that function call is first made.
The mutex can be controlled using the regulator_lock/unlock() API.

Fixes: 99cf3af5e2d5 ("regulator: pv88080: new regulator driver")
Suggested-by: Adam Thomson <Adam.Thomson.Opensource@...semi.com>
Signed-off-by: Steve Twiss <stwiss.opensource@...semi.com>
Signed-off-by: Mark Brown <broonie@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/regulator/pv88080-regulator.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/regulator/pv88080-regulator.c b/drivers/regulator/pv88080-regulator.c
index bdddacdbeb996..6279216fb2540 100644
--- a/drivers/regulator/pv88080-regulator.c
+++ b/drivers/regulator/pv88080-regulator.c
@@ -345,9 +345,11 @@ static irqreturn_t pv88080_irq_handler(int irq, void *data)
 	if (reg_val & PV88080_E_VDD_FLT) {
 		for (i = 0; i < PV88080_MAX_REGULATORS; i++) {
 			if (chip->rdev[i] != NULL) {
+			        regulator_lock(chip->rdev[i]);
 				regulator_notifier_call_chain(chip->rdev[i],
 					REGULATOR_EVENT_UNDER_VOLTAGE,
 					NULL);
+			        regulator_unlock(chip->rdev[i]);
 			}
 		}
 
@@ -362,9 +364,11 @@ static irqreturn_t pv88080_irq_handler(int irq, void *data)
 	if (reg_val & PV88080_E_OVER_TEMP) {
 		for (i = 0; i < PV88080_MAX_REGULATORS; i++) {
 			if (chip->rdev[i] != NULL) {
+			        regulator_lock(chip->rdev[i]);
 				regulator_notifier_call_chain(chip->rdev[i],
 					REGULATOR_EVENT_OVER_TEMP,
 					NULL);
+			        regulator_unlock(chip->rdev[i]);
 			}
 		}
 
-- 
2.20.1