linux-kernel - Applied "regulator: core: avoid unused variable warning" to the regulator tree

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Message-Id: <E1a3tuH-0007qZ-Q5@debutante>
Date:	Tue, 01 Dec 2015 23:00:21 +0000
From:	Mark Brown <broonie@...nel.org>
To:	Arnd Bergmann <arnd@...db.de>, Mark Brown <broonie@...nel.org>
Cc:	linux-kernel@...r.kernel.org
Subject: Applied "regulator: core: avoid unused variable warning" to the regulator tree

The patch

   regulator: core: avoid unused variable warning

has been applied to the regulator tree at

   git://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 fa731ac7ea04a7d3a5c6d2f568132478c02a83b3 Mon Sep 17 00:00:00 2001
From: Arnd Bergmann <arnd@...db.de>
Date: Fri, 20 Nov 2015 15:24:39 +0100
Subject: [PATCH] regulator: core: avoid unused variable warning

The second argument of the mutex_lock_nested() helper is only
evaluated if CONFIG_DEBUG_LOCK_ALLOC is set. Otherwise we
get this build warning for the new regulator_lock_supply
function:

drivers/regulator/core.c: In function 'regulator_lock_supply':
drivers/regulator/core.c:142:6: warning: unused variable 'i' [-Wunused-variable]

To avoid the warning, this restructures the code to make it
both simpler and to move the 'i++' outside of the mutex_lock_nested
call, where it is now always used and the variable is not
flagged as unused.

We had some discussion about changing mutex_lock_nested to an
inline function, which would make the code do the right thing here,
but in the end decided against it, in order to guarantee that
mutex_lock_nested() does not introduced overhead without
CONFIG_DEBUG_LOCK_ALLOC.

Signed-off-by: Arnd Bergmann <arnd@...db.de>
Fixes: 9f01cd4a915 ("regulator: core: introduce function to lock regulators and its supplies")
Link: http://permalink.gmane.org/gmane.linux.kernel/2068900
Signed-off-by: Mark Brown <broonie@...nel.org>
---
 drivers/regulator/core.c | 14 +++-----------
 1 file changed, 3 insertions(+), 11 deletions(-)

diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index 73b7683355cd..c70017d5f74b 100644
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -138,18 +138,10 @@ static bool have_full_constraints(void)
  */
 static void regulator_lock_supply(struct regulator_dev *rdev)
 {
-	struct regulator *supply;
-	int i = 0;
-
-	while (1) {
-		mutex_lock_nested(&rdev->mutex, i++);
-		supply = rdev->supply;
-
-		if (!rdev->supply)
-			return;
+	int i;

-		rdev = supply->rdev;
-	}
+	for (i = 0; rdev->supply; rdev = rdev->supply->rdev, i++)
+		mutex_lock_nested(&rdev->mutex, i);
 }

 /**
-- 
2.6.2

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