From 8f20660f053cefd4693e69cfff9cf58f4f7c4929 Mon Sep 17 00:00:00 2001
From: Ryan Neph <ryanneph@chromium.org>
Date: Fri, 3 Feb 2023 15:33:44 -0800
Subject: [PATCH] drm/virtio: exbuf->fence_fd unmodified on interrupted wait
Git-commit: 8f20660f053cefd4693e69cfff9cf58f4f7c4929
Patch-mainline: v6.2-rc8
References: git-fixes

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
Acked-by: Takashi Iwai <tiwai@suse.de>

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

--- a/drivers/gpu/drm/virtio/virtgpu_ioctl.c
+++ b/drivers/gpu/drm/virtio/virtgpu_ioctl.c
@@ -86,7 +86,6 @@ static int virtio_gpu_execbuffer_ioctl(s
 	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;
 
@@ -96,13 +95,11 @@ static int virtio_gpu_execbuffer_ioctl(s
 	if ((exbuf->flags & ~VIRTGPU_EXECBUF_FLAGS))
 		return -EINVAL;
 
-	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;
--- a/include/uapi/drm/virtgpu_drm.h
+++ b/include/uapi/drm/virtgpu_drm.h
@@ -61,6 +61,7 @@ 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;