freedreno/drm/virtio: Fix deadlock on exit

We don't want the retire work to be the one to drop the last reference
to the pipe, as that would result in trying to free the retire_queue
from the retire_queue thread.

Signed-off-by: Rob Clark <robdclark@chromium.org>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/28531>

src/freedreno/drm/freedreno_pipe.c

@@ -152,6 +152,9 @@ fd_pipe_purge(struct fd_pipe *pipe)
       fd_fence_flush(unflushed_fence);
       fd_fence_del(unflushed_fence);
    }
+
+   if (pipe->funcs->finish)
+      pipe->funcs->finish(pipe);
 }
 
 int

src/freedreno/drm/freedreno_priv.h

@@ -314,6 +314,7 @@ struct fd_pipe_funcs {
     * the pipe implementation)
     */
    void (*flush)(struct fd_pipe *pipe, uint32_t fence);
+   void (*finish)(struct fd_pipe *pipe);
 
    int (*get_param)(struct fd_pipe *pipe, enum fd_param_id param,
                     uint64_t *value);

src/freedreno/drm/virtio/virtio_pipe.c

@@ -112,6 +112,14 @@ virtio_pipe_get_param(struct fd_pipe *pipe, enum fd_param_id param,
    }
 }
 
+static void
+virtio_pipe_finish(struct fd_pipe *pipe)
+{
+   struct virtio_pipe *virtio_pipe = to_virtio_pipe(pipe);
+   if (util_queue_is_initialized(&virtio_pipe->retire_queue))
+      util_queue_finish(&virtio_pipe->retire_queue);
+}
+
 static int
 virtio_pipe_wait(struct fd_pipe *pipe, const struct fd_fence *fence, uint64_t timeout)
 {
@@ -208,6 +216,7 @@ static const struct fd_pipe_funcs funcs = {
    .ringbuffer_new_object = fd_ringbuffer_sp_new_object,
    .submit_new = virtio_submit_new,
    .flush = fd_pipe_sp_flush,
+   .finish = virtio_pipe_finish,
    .get_param = virtio_pipe_get_param,
    .wait = virtio_pipe_wait,
    .destroy = virtio_pipe_destroy,