An interrupted dma_fence_wait() becomes an -ERESTARTSYS returned
to userspace ioctl(DRM_IOCTL_VIRTGPU_EXECBUFFER) calls, prompting to
retry the ioctl(), but the passed exbuf->fence_fd has been reset to -1,
making the retry attempt fail at sync_file_get_fence().

The uapi for DRM_IOCTL_VIRTGPU_EXECBUFFER is changed to retain the
passed value for exbuf->fence_fd when returning anything besides a
successful result from the ioctl.

Fixes: 2cd7b6f08bc4 ("drm/virtio: add in/out fence support for explicit 
synchronization")
Signed-off-by: Ryan Neph <[email protected]>
Reviewed-by: Rob Clark <[email protected]>
Reviewed-by: Dmitry Osipenko <[email protected]>

---

Changes in v2:
- No longer modifies exbuf->fence_fd unless DRM_IOCTL_VIRTGPU_EXECBUFFER
  succeeds.
- Added r-b tags (Rob/Dmitry) from v1.

 drivers/gpu/drm/virtio/virtgpu_ioctl.c | 5 +----
 include/uapi/drm/virtgpu_drm.h         | 1 +
 2 files changed, 2 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/virtio/virtgpu_ioctl.c 
b/drivers/gpu/drm/virtio/virtgpu_ioctl.c
index 9f4a90493aea..da45215a933d 100644
--- a/drivers/gpu/drm/virtio/virtgpu_ioctl.c
+++ b/drivers/gpu/drm/virtio/virtgpu_ioctl.c
@@ -126,7 +126,6 @@ static int virtio_gpu_execbuffer_ioctl(struct drm_device 
*dev, void *data,
        void __user *user_bo_handles = NULL;
        struct virtio_gpu_object_array *buflist = NULL;
        struct sync_file *sync_file;
-       int in_fence_fd = exbuf->fence_fd;
        int out_fence_fd = -1;
        void *buf;
        uint64_t fence_ctx;
@@ -152,13 +151,11 @@ static int virtio_gpu_execbuffer_ioctl(struct drm_device 
*dev, void *data,
                ring_idx = exbuf->ring_idx;
        }
 
-       exbuf->fence_fd = -1;
-
        virtio_gpu_create_context(dev, file);
        if (exbuf->flags & VIRTGPU_EXECBUF_FENCE_FD_IN) {
                struct dma_fence *in_fence;
 
-               in_fence = sync_file_get_fence(in_fence_fd);
+               in_fence = sync_file_get_fence(exbuf->fence_fd);
 
                if (!in_fence)
                        return -EINVAL;
diff --git a/include/uapi/drm/virtgpu_drm.h b/include/uapi/drm/virtgpu_drm.h
index 0512fde5e697..7b158fcb02b4 100644
--- a/include/uapi/drm/virtgpu_drm.h
+++ b/include/uapi/drm/virtgpu_drm.h
@@ -64,6 +64,7 @@ struct drm_virtgpu_map {
        __u32 pad;
 };
 
+/* fence_fd is modified on success if VIRTGPU_EXECBUF_FENCE_FD_OUT flag is 
set. */
 struct drm_virtgpu_execbuffer {
        __u32 flags;
        __u32 size;
-- 
2.39.1.519.gcb327c4b5f-goog

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