drm/virtio: fix virtio_gpu_execbuffer_ioctl locking

Lockdep says we can't call vmemdup() while having objects reserved
because it needs the mmap semaphore.  So reorder the calls reserve
the objects later.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Chia-I Wu <olvaffe@gmail.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20200211135047.22261-2-kraxel@redhat.com

diff --git a/drivers/gpu/drm/virtio/virtgpu_ioctl.c b/drivers/gpu/drm/virtio/virtgpu_ioctl.c
index 205ec4a..0477d12 100644 (file)
--- a/drivers/gpu/drm/virtio/virtgpu_ioctl.c
+++ b/drivers/gpu/drm/virtio/virtgpu_ioctl.c
@@ -126,22 +126,22 @@ static int virtio_gpu_execbuffer_ioctl(struct drm_device *dev, void *data,
                bo_handles = NULL;
        }
 
-       if (buflist) {
-               ret = virtio_gpu_array_lock_resv(buflist);
-               if (ret)
-                       goto out_unused_fd;
-       }
-
        buf = vmemdup_user(u64_to_user_ptr(exbuf->command), exbuf->size);
        if (IS_ERR(buf)) {
                ret = PTR_ERR(buf);
-               goto out_unresv;
+               goto out_unused_fd;
+       }
+
+       if (buflist) {
+               ret = virtio_gpu_array_lock_resv(buflist);
+               if (ret)
+                       goto out_memdup;
        }
 
        out_fence = virtio_gpu_fence_alloc(vgdev);
        if(!out_fence) {
                ret = -ENOMEM;
-               goto out_memdup;
+               goto out_unresv;
        }
 
        if (out_fence_fd >= 0) {
@@ -160,11 +160,11 @@ static int virtio_gpu_execbuffer_ioctl(struct drm_device *dev, void *data,
                              vfpriv->ctx_id, buflist, out_fence);
        return 0;
 
-out_memdup:
-       kvfree(buf);
 out_unresv:
        if (buflist)
                virtio_gpu_array_unlock_resv(buflist);
+out_memdup:
+       kvfree(buf);
 out_unused_fd:
        kvfree(bo_handles);
        if (buflist)