[PATCH] drm/virtgpu: Use ERR_PTR for fb_create callback error return

[PATCH] drm/virtgpu: Use ERR_PTR for fb_create callback error return

[liuqiangneo]

From: Qiang Liu <liuqiang@kylinos.cn>

The fb_create callback returns an error code encoded with ERR_PTR()
on failure. This lets the caller see the actual error code instead of
just a generic failure.

Signed-off-by: Qiang Liu <liuqiang@kylinos.cn>
---
 drivers/gpu/drm/virtio/virtgpu_display.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/virtio/virtgpu_display.c b/drivers/gpu/drm/virtio/virtgpu_display.c
index 44ffffec550f..85ea252c658e 100644
--- a/drivers/gpu/drm/virtio/virtgpu_display.c
+++ b/drivers/gpu/drm/virtio/virtgpu_display.c
@@ -344,7 +344,7 @@ virtio_gpu_user_framebuffer_create(struct drm_device *dev,
 	if (ret) {
 		kfree(virtio_gpu_fb);
 		drm_gem_object_put(obj);
-		return NULL;
+		return ERR_PTR(ret);
 	}
 
 	return &virtio_gpu_fb->base;
-- 
2.43.0

Claude review: drm/virtgpu: Use ERR_PTR for fb_create callback error return

[Claude Code Review Bot]

Overall Series Review

Subject: drm/virtgpu: Use ERR_PTR for fb_create callback error return
Author: liuqiangneo@163.com
Patches: 1
Reviewed: 2026-06-05T06:40:48.679987

---

This is a single-patch series that fixes a real bug in the `virtio_gpu_user_framebuffer_create` function. The `fb_create` callback contract (documented in `drm_mode_config.h:78-81`) explicitly states it must return "a negative error code encoded with ERR_PTR()" on failure. However, one error path was returning `NULL` instead, which violates this contract and would cause the DRM core caller to misinterpret the error.

The fix is correct, minimal, and consistent with the other error paths in the same function, which all already use `ERR_PTR()`. This is a clear bug fix — **recommend accepting**.

---
Generated by Claude Code Patch Reviewer

Claude review: drm/virtgpu: Use ERR_PTR for fb_create callback error return

[Claude Code Review Bot]

Patch Review

**Correctness: Good.** The `fb_create` callback's return contract is documented in `include/drm/drm_mode_config.h:78-81`:

> RETURNS: A new framebuffer with an initial reference count of 1 or a negative error code encoded with ERR_PTR().

The caller in the DRM core will use `IS_ERR()` to check the return value. Returning `NULL` instead of `ERR_PTR()` means the caller would not detect the error — it would treat `NULL` as a valid framebuffer pointer, leading to a null pointer dereference.

**Consistency: Good.** Looking at the patched function (`virtgpu_display.c:318-351`), the three other error paths in `virtio_gpu_user_framebuffer_create` already return `ERR_PTR()` correctly:

```c
return ERR_PTR(-ENOENT);   // line 330 - bad pixel format
return ERR_PTR(-EINVAL);   // line 335 - object lookup failure
return ERR_PTR(-ENOMEM);   // line 340 - allocation failure
```

Only the `virtio_gpu_framebuffer_init` failure path (the one being fixed) was inconsistent, returning `NULL`. The fix changes it to `ERR_PTR(ret)`, which correctly propagates the actual error code from `virtio_gpu_framebuffer_init`.

**No issues found.** Clean, minimal, correct fix.

---
Generated by Claude Code Patch Reviewer