Patch "drm/exynos: fix error handling in exynos_drm_subdrv_open" has been added to the 4.4-stable tree

Patch "drm/exynos: fix error handling in exynos_drm_subdrv_open" has been added to the 4.4-stable tree

[gregkh]

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

    drm/exynos: fix error handling in exynos_drm_subdrv_open

to the 4.4-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:
     drm-exynos-fix-error-handling-in-exynos_drm_subdrv_open.patch
and it can be found in the queue-4.4 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 55c4b906aa2aec3fa66310ec03c6842e34a04b2a Mon Sep 17 00:00:00 2001
From: Arnd Bergmann <arnd@arndb.de>
Date: Mon, 14 Mar 2016 15:22:25 +0100
Subject: drm/exynos: fix error handling in exynos_drm_subdrv_open

From: Arnd Bergmann <arnd@arndb.de>

commit 55c4b906aa2aec3fa66310ec03c6842e34a04b2a upstream.

gcc-6 warns about a pointless loop in exynos_drm_subdrv_open:

drivers/gpu/drm/exynos/exynos_drm_core.c: In function 'exynos_drm_subdrv_open':
drivers/gpu/drm/exynos/exynos_drm_core.c:104:199: error: self-comparison always evaluates to false [-Werror=tautological-compare]
  list_for_each_entry_reverse(subdrv, &subdrv->list, list) {

Here, the list_for_each_entry_reverse immediately terminates because
the subdrv pointer is compared to itself as the loop end condition.

If we were to take the current subdrv pointer as the start of the
list (as we would do if list_for_each_entry_reverse() was not a macro),
we would iterate backwards over the &exynos_drm_subdrv_list anchor,
which would be even worse.

Instead, we need to use list_for_each_entry_continue_reverse()
to go back over each subdrv that was successfully opened until
the first entry.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Inki Dae <inki.dae@samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/gpu/drm/exynos/exynos_drm_core.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/gpu/drm/exynos/exynos_drm_core.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_core.c
@@ -101,7 +101,7 @@ int exynos_drm_subdrv_open(struct drm_de
 	return 0;
 
 err:
-	list_for_each_entry_reverse(subdrv, &subdrv->list, list) {
+	list_for_each_entry_continue_reverse(subdrv, &exynos_drm_subdrv_list, list) {
 		if (subdrv->close)
 			subdrv->close(dev, subdrv->dev, file);
 	}


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

queue-4.4/drm-exynos-fix-error-handling-in-exynos_drm_subdrv_open.patch
queue-4.4/arm-8584-1-floppy-avoid-gcc-6-warning.patch
queue-4.4/powerpc-ptrace-fix-out-of-bounds-array-access-warning.patch
queue-4.4/cgroup-avoid-false-positive-gcc-6-warning.patch
queue-4.4/smc91x-avoid-self-comparison-warning.patch