etnaviv: prevent deadlock in error path

If drmPrimeFDToHandle fails in etna_bo_from_dmabuf, the function must
not return with the table_lock mutex held. Unlock the mutex in the error
path.

Based on ceb70a6b10 ("freedreno: prevent deadlock in error path").

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Reviewed-by: Eric Engestrom <eric.engestrom@imgtec.com>

etnaviv/etnaviv_bo.c

@@ -206,10 +206,15 @@ struct etna_bo *etna_bo_from_dmabuf(struct etna_device *dev, int fd)
 	int ret, size;
 	uint32_t handle;
 
+	/* take the lock before calling drmPrimeFDToHandle to avoid
+	 * racing against etna_bo_del, which might invalidate the
+	 * returned handle.
+	 */
 	pthread_mutex_lock(&table_lock);
 
 	ret = drmPrimeFDToHandle(dev->fd, fd, &handle);
 	if (ret) {
+		pthread_mutex_unlock(&table_lock);
 		return NULL;
 	}