[PATCH] [STABLE-4.13] [media] imx-media-of: avoid uninitialized variable warning

[PATCH] [STABLE-4.13] [media] imx-media-of: avoid uninitialized variable warning

[Arnd Bergmann]

Replaces upstream commit 0b2e9e7947e7 ("media: staging/imx: remove
confusing IS_ERR_OR_NULL usage")

We get a harmless warning about a potential uninitialized variable
use in the driver:

drivers/staging/media/imx/imx-media-of.c: In function 'of_parse_subdev':
drivers/staging/media/imx/imx-media-of.c:216:4: warning: 'remote_np' may be used uninitialized in this function [-Wmaybe-uninitialized]

I reworked that code to be easier to understand by gcc in mainline,
but that commit is too large to backport. This is a much simpler
workaround, avoiding the warning by adding a fake initialization
to the variable. The driver was only introduced in linux-4.13,
so the workaround is not needed for earlier stable kernels.

Fixes: e130291212df ("[media] media: Add i.MX media core driver")
Cc: stable@vger.kernel.org
Cc: Philipp Zabel <p.zabel@pengutronix.de>
Cc: Steve Longerbeam <steve_longerbeam@mentor.com>
Cc: Hans Verkuil <hans.verkuil@cisco.com>
Cc: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 drivers/staging/media/imx/imx-media-of.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/staging/media/imx/imx-media-of.c b/drivers/staging/media/imx/imx-media-of.c
index b026fe66467c..90e7e702a411 100644
--- a/drivers/staging/media/imx/imx-media-of.c
+++ b/drivers/staging/media/imx/imx-media-of.c
@@ -167,7 +167,7 @@ of_parse_subdev(struct imx_media_dev *imxmd, struct device_node *sd_np,
 		of_parse_sensor(imxmd, imxsd, sd_np);
 
 	for (i = 0; i < num_pads; i++) {
-		struct device_node *epnode = NULL, *port, *remote_np;
+		struct device_node *epnode = NULL, *port, *remote_np = NULL;
 		struct imx_media_subdev *remote_imxsd;
 		struct imx_media_pad *pad;
 		int remote_pad;
-- 
2.9.0

Patch "[media] imx-media-of: avoid uninitialized variable warning" has been added to the 4.13-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    [media] imx-media-of: avoid uninitialized variable warning

to the 4.13-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     imx-media-of-avoid-uninitialized-variable-warning.patch
and it can be found in the queue-4.13 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From arnd@arndb.de  Thu Oct  5 11:08:57 2017
From: Arnd Bergmann <arnd@arndb.de>
Date: Wed,  4 Oct 2017 15:34:55 +0200
Subject: [media] imx-media-of: avoid uninitialized variable warning
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Arnd Bergmann <arnd@arndb.de>, stable@vger.kernel.org, Philipp Zabel <p.zabel@pengutronix.de>, Steve Longerbeam <steve_longerbeam@mentor.com>, Hans Verkuil <hans.verkuil@cisco.com>, Mauro Carvalho Chehab <mchehab@s-opensource.com>, Steve Longerbeam <slongerbeam@gmail.com>, Mauro Carvalho Chehab <mchehab@kernel.org>, Russell King <rmk+kernel@armlinux.org.uk>, linux-media@vger.kernel.org, devel@driverdev.osuosl.org, linux-kernel@vger.kernel.org
Message-ID: <20171004133507.3539072-1-arnd@arndb.de>


From: Arnd Bergmann <arnd@arndb.de>

Replaces upstream commit 0b2e9e7947e7 ("media: staging/imx: remove
confusing IS_ERR_OR_NULL usage")

We get a harmless warning about a potential uninitialized variable
use in the driver:

drivers/staging/media/imx/imx-media-of.c: In function 'of_parse_subdev':
drivers/staging/media/imx/imx-media-of.c:216:4: warning: 'remote_np' may be used uninitialized in this function [-Wmaybe-uninitialized]

I reworked that code to be easier to understand by gcc in mainline,
but that commit is too large to backport. This is a much simpler
workaround, avoiding the warning by adding a fake initialization
to the variable. The driver was only introduced in linux-4.13,
so the workaround is not needed for earlier stable kernels.

Fixes: e130291212df ("[media] media: Add i.MX media core driver")
Cc: stable@vger.kernel.org
Cc: Philipp Zabel <p.zabel@pengutronix.de>
Cc: Steve Longerbeam <steve_longerbeam@mentor.com>
Cc: Hans Verkuil <hans.verkuil@cisco.com>
Cc: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/staging/media/imx/imx-media-of.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/staging/media/imx/imx-media-of.c
+++ b/drivers/staging/media/imx/imx-media-of.c
@@ -167,7 +167,7 @@ of_parse_subdev(struct imx_media_dev *im
 		of_parse_sensor(imxmd, imxsd, sd_np);
 
 	for (i = 0; i < num_pads; i++) {
-		struct device_node *epnode = NULL, *port, *remote_np;
+		struct device_node *epnode = NULL, *port, *remote_np = NULL;
 		struct imx_media_subdev *remote_imxsd;
 		struct imx_media_pad *pad;
 		int remote_pad;


Patches currently in stable-queue which might be from arnd@arndb.de are

queue-4.13/imx-media-of-avoid-uninitialized-variable-warning.patch

Re: [PATCH] [STABLE-4.13] [media] imx-media-of: avoid uninitialized variable warning

[Dan Carpenter]

On Wed, Oct 04, 2017 at 03:34:55PM +0200, Arnd Bergmann wrote:
> Replaces upstream commit 0b2e9e7947e7 ("media: staging/imx: remove
> confusing IS_ERR_OR_NULL usage")
> 
> We get a harmless warning about a potential uninitialized variable
> use in the driver:
> 
> drivers/staging/media/imx/imx-media-of.c: In function 'of_parse_subdev':
> drivers/staging/media/imx/imx-media-of.c:216:4: warning: 'remote_np' may be used uninitialized in this function [-Wmaybe-uninitialized]
> 
> I reworked that code to be easier to understand by gcc in mainline,
> but that commit is too large to backport. This is a much simpler
> workaround, avoiding the warning by adding a fake initialization
> to the variable. The driver was only introduced in linux-4.13,
> so the workaround is not needed for earlier stable kernels.
> 
> Fixes: e130291212df ("[media] media: Add i.MX media core driver")

I normally leave off the Fixes tag when it's not a bugfix.  The warning
is, as you mentioned, harmless.

regards,
dan carpenter