linux-kernel - [PATCH 04/13] regulator: da9211: Fix notifier mutex lock warning

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Date:   Tue, 26 Feb 2019 15:27:57 +0000
From:   Steve Twiss <stwiss.opensource@...semi.com>
To:     Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>
CC:     Support Opensource <support.opensource@...semi.com>,
        LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH 04/13] regulator: da9211: Fix notifier mutex lock warning

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: 1028a37daa14 ("regulator: da9211: new regulator driver")
Suggested-by: Adam Thomson <Adam.Thomson.Opensource@...semi.com>
Signed-off-by: Steve Twiss <stwiss.opensource@...semi.com>
---
 drivers/regulator/da9211-regulator.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/regulator/da9211-regulator.c b/drivers/regulator/da9211-regulator.c
index 109ee12..4d7fe48 100644
--- a/drivers/regulator/da9211-regulator.c
+++ b/drivers/regulator/da9211-regulator.c
@@ -322,8 +322,10 @@ static irqreturn_t da9211_irq_handler(int irq, void *data)
 		goto error_i2c;
 
 	if (reg_val & DA9211_E_OV_CURR_A) {
+	        regulator_lock(chip->rdev[0]);
 		regulator_notifier_call_chain(chip->rdev[0],
 			REGULATOR_EVENT_OVER_CURRENT, NULL);
+	        regulator_unlock(chip->rdev[0]);
 
 		err = regmap_write(chip->regmap, DA9211_REG_EVENT_B,
 			DA9211_E_OV_CURR_A);
@@ -334,8 +336,10 @@ static irqreturn_t da9211_irq_handler(int irq, void *data)
 	}
 
 	if (reg_val & DA9211_E_OV_CURR_B) {
+	        regulator_lock(chip->rdev[1]);
 		regulator_notifier_call_chain(chip->rdev[1],
 			REGULATOR_EVENT_OVER_CURRENT, NULL);
+	        regulator_unlock(chip->rdev[1]);
 
 		err = regmap_write(chip->regmap, DA9211_REG_EVENT_B,
 			DA9211_E_OV_CURR_B);
-- 
1.9.3