drm/nvc0/fb: fix crash when different mutex is used to protect same list
drm/nvc0/fb: fix crash when different mutex is used to protect same list

Fixes regression introduced in commit 861d2107
"drm/nouveau/fb: merge fb/vram and port to subdev interfaces"

nv50_fb_vram_{new,del} functions were changed to use
nouveau_subdev->mutex instead of the old nouveau_mm->mutex.
nvc0_fb_vram_new still uses the nouveau_mm->mutex, but nvc0 doesn't
have its own fb_vram_del function, using nv50_fb_vram_del instead.
Because of this, on nvc0 a different mutex ends up being used to protect
additions and deletions to the same list.

This patch is a -stable candidate for 3.7.

Signed-off-by: Aleksi Torhamo <ef392cb6f5fd3506d64f7fd922ad44a3838dde49@torhamo.net>
Reported-by: Roy Spliet <e16bf78a1483ab993c7c212aa768af19f2d12eb8@student.tudelft.nl>
Tested-by: Roy Spliet <e16bf78a1483ab993c7c212aa768af19f2d12eb8@student.tudelft.nl>
Signed-off-by: Ben Skeggs <d9f27fb07c1e9f131223ad827fa5179f3846c30b@redhat.com>
Cc: 4fbacc2fa0ffdbb11bf1ad6925b886ebd08dd15f@vger.kernel.org

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas