regulator: lp8755: Fix notifier mutex lock warning

BugLink: https://bugs.launchpad.net/bugs/1837517
[ Upstream commit 89b2758c192c35068b07766a6830433bfbdc1f44 ]

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: b59320cc5a5e ("regulator: lp8755: new driver for LP8755")
Suggested-by: Adam Thomson <Adam.Thomson.Opensource@diasemi.com>
Signed-off-by: Steve Twiss <stwiss.opensource@diasemi.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

diff --git a/drivers/regulator/lp8755.c b/drivers/regulator/lp8755.c
index 244822bb63cd6bf1fedf180a6eef93370951fcad..d82d3077f3b82a0c84fae98ddfd56b736204b72f 100644 (file)
--- a/drivers/regulator/lp8755.c
+++ b/drivers/regulator/lp8755.c
@@ -372,10 +372,13 @@ static irqreturn_t lp8755_irq_handler(int irq, void *data)
        for (icnt = 0; icnt < LP8755_BUCK_MAX; icnt++)
                if ((flag0 & (0x4 << icnt))
                    && (pchip->irqmask & (0x04 << icnt))
-                   && (pchip->rdev[icnt] != NULL))
+                   && (pchip->rdev[icnt] != NULL)) {
+                       regulator_lock(pchip->rdev[icnt]);
                        regulator_notifier_call_chain(pchip->rdev[icnt],
                                                      LP8755_EVENT_PWR_FAULT,
                                                      NULL);
+                       regulator_unlock(pchip->rdev[icnt]);
+               }
 
        /* read flag1 register */
        ret = lp8755_read(pchip, 0x0E, &flag1);
@@ -389,18 +392,24 @@ static irqreturn_t lp8755_irq_handler(int irq, void *data)
        /* send OCP event to all regualtor devices */
        if ((flag1 & 0x01) && (pchip->irqmask & 0x01))
                for (icnt = 0; icnt < LP8755_BUCK_MAX; icnt++)
-                       if (pchip->rdev[icnt] != NULL)
+                       if (pchip->rdev[icnt] != NULL) {
+                               regulator_lock(pchip->rdev[icnt]);
                                regulator_notifier_call_chain(pchip->rdev[icnt],
                                                              LP8755_EVENT_OCP,
                                                              NULL);
+                               regulator_unlock(pchip->rdev[icnt]);
+                       }
 
        /* send OVP event to all regualtor devices */
        if ((flag1 & 0x02) && (pchip->irqmask & 0x02))
                for (icnt = 0; icnt < LP8755_BUCK_MAX; icnt++)
-                       if (pchip->rdev[icnt] != NULL)
+                       if (pchip->rdev[icnt] != NULL) {
+                               regulator_lock(pchip->rdev[icnt]);
                                regulator_notifier_call_chain(pchip->rdev[icnt],
                                                              LP8755_EVENT_OVP,
                                                              NULL);
+                               regulator_unlock(pchip->rdev[icnt]);
+                       }
        return IRQ_HANDLED;
 
 err_i2c: