linux-kernel - Applied "regulator: wm831x ldo: Fix notifier mutex lock warning" to the regulator tree

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Message-Id: <20190313153912.36AAE1128B97@debutante.sirena.org.uk>
Date:   Wed, 13 Mar 2019 15:39:12 +0000 (GMT)
From:   Mark Brown <broonie@...nel.org>
To:     Steve Twiss <stwiss.opensource@...semi.com>
Cc:     Charles Keepax <ckeepax@...nsource.cirrus.com>,
        Mark Brown <broonie@...nel.org>, linux-kernel@...r.kernel.org
Subject: Applied "regulator: wm831x ldo: Fix notifier mutex lock warning" to the regulator tree

The patch

   regulator: wm831x ldo: Fix notifier mutex lock warning

has been applied to the regulator tree at

   https://git.kernel.org/pub/scm/linux/kernel/git/broonie/regulator.git 

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.  

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark

>From 8be64b6d87bd47d81753b60ddafe70102ebfd76b Mon Sep 17 00:00:00 2001
From: Steve Twiss <stwiss.opensource@...semi.com>
Date: Tue, 26 Feb 2019 15:54:01 +0000
Subject: [PATCH] regulator: wm831x ldo: 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: d1c6b4fe668b ("regulator: Add WM831x LDO support")
Suggested-by: Adam Thomson <Adam.Thomson.Opensource@...semi.com>
Signed-off-by: Steve Twiss <stwiss.opensource@...semi.com>
Acked-by: Charles Keepax <ckeepax@...nsource.cirrus.com>
Signed-off-by: Mark Brown <broonie@...nel.org>
---
 drivers/regulator/wm831x-ldo.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/regulator/wm831x-ldo.c b/drivers/regulator/wm831x-ldo.c
index e4a6f888484e..fcd038e7cd80 100644
--- a/drivers/regulator/wm831x-ldo.c
+++ b/drivers/regulator/wm831x-ldo.c
@@ -51,9 +51,11 @@ static irqreturn_t wm831x_ldo_uv_irq(int irq, void *data)
 {
 	struct wm831x_ldo *ldo = data;

+	regulator_lock(ldo->regulator);
 	regulator_notifier_call_chain(ldo->regulator,
 				      REGULATOR_EVENT_UNDER_VOLTAGE,
 				      NULL);
+	regulator_unlock(ldo->regulator);

 	return IRQ_HANDLED;
 }
-- 
2.20.1