drm/virtio: exbuf->fence_fd unmodified on interrupted wait

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 <ryanneph@chromium.org>
Reviewed-by: Rob Clark <robdclark@gmail.com>
Reviewed-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Signed-off-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230203233345.2477767-1-ryanneph@chromium.org

diff --git a/drivers/gpu/drm/virtio/virtgpu_ioctl.c b/drivers/gpu/drm/virtio/virtgpu_ioctl.c
index 9f4a904..da45215 100644 (file)
--- 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 0512fde..7b158fc 100644 (file)
--- 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;