[PATCH 5.15.y] drm/virtio: Fix error code in virtio_gpu_object_shmem_init()

[Harshit Mogalapalli]

In virtio_gpu_object_shmem_init() we are passing NULL to PTR_ERR, which
is returning 0/success.

Fix this by storing error value in 'ret' variable before assigning
shmem->pages to NULL.

Found using static analysis with Smatch.

Fixes: 64b88afbd92f ("drm/virtio: Correct drm_gem_shmem_get_sg_table() error handling")
Signed-off-by: Harshit Mogalapalli <harshit.m.mogalapalli@xxxxxxxxxx>
---
Only compile tested.

Upstream commit b5c9ed70d1a9 ("drm/virtio: Improve DMA API usage for shmem BOs")
deleted this code, so this patch is not necessary in linux-6.1.y and
linux-6.2.y.
---
 drivers/gpu/drm/virtio/virtgpu_object.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/virtio/virtgpu_object.c b/drivers/gpu/drm/virtio/virtgpu_object.c
index 7e75fb0fc7bd..25d399b00404 100644
--- a/drivers/gpu/drm/virtio/virtgpu_object.c
+++ b/drivers/gpu/drm/virtio/virtgpu_object.c
@@ -169,8 +169,9 @@ static int virtio_gpu_object_shmem_init(struct virtio_gpu_device *vgdev,
 	shmem->pages = drm_gem_shmem_get_sg_table(&bo->base);
 	if (IS_ERR(shmem->pages)) {
 		drm_gem_shmem_unpin(&bo->base);
+		ret = PTR_ERR(shmem->pages);
 		shmem->pages = NULL;
-		return PTR_ERR(shmem->pages);
+		return ret;
 	}
 
 	if (use_dma_api) {
-- 
2.31.1