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 <aleksi@torhamo.net>
Reported-by: Roy Spliet <r.spliet@student.tudelft.nl>
Tested-by: Roy Spliet <r.spliet@student.tudelft.nl>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Cc: stable@vger.kernel.org

1 files changed, 3 insertions, 3 deletions

diff --git a/drivers/gpu/drm/nouveau/core/subdev/fb/nvc0.c b/drivers/gpu/drm/nouveau/core/subdev/fb/nvc0.c
index 306bdf12145..7606ed15b6f 100644
--- a/drivers/gpu/drm/nouveau/core/subdev/fb/nvc0.c
+++ b/drivers/gpu/drm/nouveau/core/subdev/fb/nvc0.c
@@ -145,14 +145,14 @@ nvc0_fb_vram_new(struct nouveau_fb *pfb, u64 size, u32 align, u32 ncmin,
         mem->memtype = type;
         mem->size = size;
 
-        mutex_lock(&mm->mutex);
+        mutex_lock(&pfb->base.mutex);
         do {
                 if (back)
                         ret = nouveau_mm_tail(mm, 1, size, ncmin, align, &r);
                 else
                         ret = nouveau_mm_head(mm, 1, size, ncmin, align, &r);
                 if (ret) {
-                        mutex_unlock(&mm->mutex);
+                        mutex_unlock(&pfb->base.mutex);
                         pfb->ram.put(pfb, &mem);
                         return ret;
                 }
@@ -160,7 +160,7 @@ nvc0_fb_vram_new(struct nouveau_fb *pfb, u64 size, u32 align, u32 ncmin,
                 list_add_tail(&r->rl_entry, &mem->regions);
                 size -= r->length;
         } while (size);
-        mutex_unlock(&mm->mutex);
+        mutex_unlock(&pfb->base.mutex);
 
         r = list_first_entry(&mem->regions, struct nouveau_mm_node, rl_entry);
         mem->offset = (u64)r->offset << 12;