[PATCH 07/13] regulator: ltc3676: Fix notifier mutex lock warning

[Steve Twiss]

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: 37b918a034fe ("regulator: Add LTC3676 support")
Suggested-by: Adam Thomson <adam.thomson.opensou...@diasemi.com>
Signed-off-by: Steve Twiss <stwiss.opensou...@diasemi.com>
---
 drivers/regulator/ltc3676.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/regulator/ltc3676.c b/drivers/regulator/ltc3676.c
index 71fd0f2..cd0f112 100644
--- a/drivers/regulator/ltc3676.c
+++ b/drivers/regulator/ltc3676.c
@@ -338,17 +338,23 @@ static irqreturn_t ltc3676_isr(int irq, void *dev_id)
        if (irqstat & LTC3676_IRQSTAT_THERMAL_WARN) {
                dev_warn(dev, "Over-temperature Warning\n");
                event = REGULATOR_EVENT_OVER_TEMP;
-               for (i = 0; i < LTC3676_NUM_REGULATORS; i++)
+               for (i = 0; i < LTC3676_NUM_REGULATORS; i++) {
+                       regulator_lock(ltc3676->regulators[i]);
                        regulator_notifier_call_chain(ltc3676->regulators[i],
                                                      event, NULL);
+                       regulator_unlock(ltc3676->regulators[i]);
+               }
        }
 
        if (irqstat & LTC3676_IRQSTAT_UNDERVOLT_WARN) {
                dev_info(dev, "Undervoltage Warning\n");
                event = REGULATOR_EVENT_UNDER_VOLTAGE;
-               for (i = 0; i < LTC3676_NUM_REGULATORS; i++)
+               for (i = 0; i < LTC3676_NUM_REGULATORS; i++) {
+                       regulator_lock(ltc3676->regulators[i]);
                        regulator_notifier_call_chain(ltc3676->regulators[i],
                                                      event, NULL);
+                       regulator_unlock(ltc3676->regulators[i]);
+               }
        }
 
        /* Clear warning condition */
-- 
1.9.3