drm/nouveau: Don't take struct_mutex around the pushbuf IOCTL.

We don't need it and it can lead to lock order inversions with respect
to drm_global_mutex, potentially causing dead locks.

Signed-off-by: Francisco Jerez <currojerez@riseup.net>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

1 files changed, 2 insertions, 5 deletions

diff --git a/drivers/gpu/drm/nouveau/nouveau_gem.c b/drivers/gpu/drm/nouveau/nouveau_gem.c
index 93711dfcafc1..10cace94395c 100644
--- a/drivers/gpu/drm/nouveau/nouveau_gem.c
+++ b/drivers/gpu/drm/nouveau/nouveau_gem.c
@@ -245,7 +245,7 @@ validate_fini_list(struct list_head *list, struct nouveau_fence *fence)
                 list_del(&nvbo->entry);
                 nvbo->reserved_by = NULL;
                 ttm_bo_unreserve(&nvbo->bo);
-                drm_gem_object_unreference(nvbo->gem);
+                drm_gem_object_unreference_unlocked(nvbo->gem);
         }
 }
 
@@ -300,7 +300,7 @@ retry:
                         validate_fini(op, NULL);
                         if (ret == -EAGAIN)
                                 ret = ttm_bo_wait_unreserved(&nvbo->bo, false);
-                        drm_gem_object_unreference(gem);
+                        drm_gem_object_unreference_unlocked(gem);
                         if (ret) {
                                 NV_ERROR(dev, "fail reserve\n");
                                 return ret;
@@ -616,8 +616,6 @@ nouveau_gem_ioctl_pushbuf(struct drm_device *dev, void *data,
                 return PTR_ERR(bo);
         }
 
-        mutex_lock(&dev->struct_mutex);
-
         /* Mark push buffers as being used on PFIFO, the validation code
          * will then make sure that if the pushbuf bo moves, that they
          * happen on the kernel channel, which will in turn cause a sync
@@ -731,7 +729,6 @@ nouveau_gem_ioctl_pushbuf(struct drm_device *dev, void *data,
 out:
         validate_fini(&op, fence);
         nouveau_fence_unref((void**)&fence);
-        mutex_unlock(&dev->struct_mutex);
         kfree(bo);
         kfree(push);