drm: Avoid client deadlocks when the master disappears.

This is done by 1) Wake up lock waiters when we close the master file descriptor. Not when the master structure is removed, since the latter requires the waiters themselves to release the refcount on the master structure -> Deadlock. 2) Send a SIGTERM to all clients waiting for the lock. Normally these clients will get a SIGPIPE when the X server dies, but clients may also spin trying to grab the DRM lock, without getting any sort of notification. Signed-off-by: Thomas Hellstrom <[email protected]> Signed-off-by: Dave Airlie <[email protected]>
blinkosm · Mar 2, 2009 · fda714c · fda714c
1 parent 171901d
commit fda714c
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Showing 3 changed files with 15 additions and 8 deletions.
diff --git a/drivers/gpu/drm/drm_fops.c b/drivers/gpu/drm/drm_fops.c
@@ -484,13 +484,27 @@ int drm_release(struct inode *inode, struct file *filp)
 	mutex_lock(&dev->struct_mutex);
 
 	if (file_priv->is_master) {
+		struct drm_master *master = file_priv->master;
 		struct drm_file *temp;
 		list_for_each_entry(temp, &dev->filelist, lhead) {
 			if ((temp->master == file_priv->master) &&
 			    (temp != file_priv))
 				temp->authenticated = 0;
 		}
 
+		/**
+		 * Since the master is disappearing, so is the
+		 * possibility to lock.
+		 */
+
+		if (master->lock.hw_lock) {
+			if (dev->sigdata.lock == master->lock.hw_lock)
+				dev->sigdata.lock = NULL;
+			master->lock.hw_lock = NULL;
+			master->lock.file_priv = NULL;
+			wake_up_interruptible_all(&master->lock.lock_queue);
+		}
+
 		if (file_priv->minor->master == file_priv->master) {
 			/* drop the reference held my the minor */
 			drm_master_put(&file_priv->minor->master);

diff --git a/drivers/gpu/drm/drm_lock.c b/drivers/gpu/drm/drm_lock.c
@@ -80,6 +80,7 @@ int drm_lock(struct drm_device *dev, void *data, struct drm_file *file_priv)
 		__set_current_state(TASK_INTERRUPTIBLE);
 		if (!master->lock.hw_lock) {
 			/* Device has been unregistered */
+			send_sig(SIGTERM, current, 0);
 			ret = -EINTR;
 			break;
 		}

diff --git a/drivers/gpu/drm/drm_stub.c b/drivers/gpu/drm/drm_stub.c
@@ -146,14 +146,6 @@ static void drm_master_destroy(struct kref *kref)
 
 	drm_ht_remove(&master->magiclist);
 
-	if (master->lock.hw_lock) {
-		if (dev->sigdata.lock == master->lock.hw_lock)
-			dev->sigdata.lock = NULL;
-		master->lock.hw_lock = NULL;
-		master->lock.file_priv = NULL;
-		wake_up_interruptible_all(&master->lock.lock_queue);
-	}
-
 	drm_free(master, sizeof(*master), DRM_MEM_DRIVER);
 }