[ 169/221] drm/nvc0/fb: fix crash when different mutex is used to protect same list

Greg Kroah-Hartman
2013-01-15T22:34:53Z

From: Aleksi Torhamo <aleksi@torhamo.net>

commit 43f789792e2c7ea2bff37195e4c4b4239e9e02b7 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/gpu/drm/nouveau/core/subdev/fb/nvc0.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

--- a/drivers/gpu/drm/nouveau/core/subdev/fb/nvc0.c
+++ b/drivers/gpu/drm/nouveau/core/subdev/fb/nvc0.c
@@ -86,14 +86,14 @@ nvc0_fb_vram_new(struct nouveau_fb *pfb,
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;
}
@@ -101,7 +101,7 @@ nvc0_fb_vram_new(struct nouveau_fb *pfb,
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;