drm/nouveau: drop drm_global_mutex before sleeping in submission path

If we keep hold of the mutex here, the process which currently holds the
buffer object will never be able to release it, causing a deadlock.

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

diff --git a/drivers/gpu/drm/nouveau/nouveau_gem.c b/drivers/gpu/drm/nouveau/nouveau_gem.c
index 613f878..93711df 100644 (file)
--- a/drivers/gpu/drm/nouveau/nouveau_gem.c
+++ b/drivers/gpu/drm/nouveau/nouveau_gem.c
@@ -337,7 +337,9 @@ retry:
                                return -EINVAL;
                        }
 
+                       mutex_unlock(&drm_global_mutex);
                        ret = ttm_bo_wait_cpu(&nvbo->bo, false);
+                       mutex_lock(&drm_global_mutex);
                        if (ret) {
                                NV_ERROR(dev, "fail wait_cpu\n");
                                return ret;