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authorChris Wilson <chris@chris-wilson.co.uk>2010-09-30 09:10:26 +0100
committerDave Airlie <airlied@redhat.com>2010-10-01 21:08:45 +1000
commit39b4d07aa3583ceefe73622841303a0a3e942ca1 (patch)
treed42f6e782f331b1d967f50ca3a02b9e51ea88515
parent29d08b3efddca628b0360411ab2b85f7b1723f48 (diff)
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drm: Hold the mutex when dropping the last GEM reference (v2)
In order to be fully threadsafe we need to check that the drm_gem_object refcount is still 0 after acquiring the mutex in order to call the free function. Otherwise, we may encounter scenarios like: Thread A: Thread B: drm_gem_close unreference_unlocked kref_put mutex_lock ... i915_gem_evict ... kref_get -> BUG ... i915_gem_unbind ... kref_put ... i915_gem_object_free ... mutex_unlock mutex_lock i915_gem_object_free -> BUG i915_gem_object_unbind kfree mutex_unlock Note that no driver is currently using the free_unlocked vfunc and it is scheduled for removal, hasten that process. Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=30454 Reported-and-Tested-by: Magnus Kessler <Magnus.Kessler@gmx.net> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: stable@kernel.org Signed-off-by: Dave Airlie <airlied@redhat.com>
-rw-r--r--drivers/gpu/drm/drm_gem.c22
-rw-r--r--include/drm/drmP.h10
2 files changed, 6 insertions, 26 deletions
diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c
index f7e61be8430..5663d271906 100644
--- a/drivers/gpu/drm/drm_gem.c
+++ b/drivers/gpu/drm/drm_gem.c
@@ -462,28 +462,6 @@ drm_gem_object_free(struct kref *kref)
}
EXPORT_SYMBOL(drm_gem_object_free);
-/**
- * Called after the last reference to the object has been lost.
- * Must be called without holding struct_mutex
- *
- * Frees the object
- */
-void
-drm_gem_object_free_unlocked(struct kref *kref)
-{
- struct drm_gem_object *obj = (struct drm_gem_object *) kref;
- struct drm_device *dev = obj->dev;
-
- if (dev->driver->gem_free_object_unlocked != NULL)
- dev->driver->gem_free_object_unlocked(obj);
- else if (dev->driver->gem_free_object != NULL) {
- mutex_lock(&dev->struct_mutex);
- dev->driver->gem_free_object(obj);
- mutex_unlock(&dev->struct_mutex);
- }
-}
-EXPORT_SYMBOL(drm_gem_object_free_unlocked);
-
static void drm_gem_object_ref_bug(struct kref *list_kref)
{
BUG();
diff --git a/include/drm/drmP.h b/include/drm/drmP.h
index 07e4726a4ee..4c9461a4f9e 100644
--- a/include/drm/drmP.h
+++ b/include/drm/drmP.h
@@ -808,7 +808,6 @@ struct drm_driver {
*/
int (*gem_init_object) (struct drm_gem_object *obj);
void (*gem_free_object) (struct drm_gem_object *obj);
- void (*gem_free_object_unlocked) (struct drm_gem_object *obj);
/* vga arb irq handler */
void (*vgaarb_irq)(struct drm_device *dev, bool state);
@@ -1456,7 +1455,6 @@ int drm_gem_init(struct drm_device *dev);
void drm_gem_destroy(struct drm_device *dev);
void drm_gem_object_release(struct drm_gem_object *obj);
void drm_gem_object_free(struct kref *kref);
-void drm_gem_object_free_unlocked(struct kref *kref);
struct drm_gem_object *drm_gem_object_alloc(struct drm_device *dev,
size_t size);
int drm_gem_object_init(struct drm_device *dev,
@@ -1484,8 +1482,12 @@ drm_gem_object_unreference(struct drm_gem_object *obj)
static inline void
drm_gem_object_unreference_unlocked(struct drm_gem_object *obj)
{
- if (obj != NULL)
- kref_put(&obj->refcount, drm_gem_object_free_unlocked);
+ if (obj != NULL) {
+ struct drm_device *dev = obj->dev;
+ mutex_lock(&dev->struct_mutex);
+ kref_put(&obj->refcount, drm_gem_object_free);
+ mutex_unlock(&dev->struct_mutex);
+ }
}
int drm_gem_handle_create(struct drm_file *file_priv,