Claude review: vgaarb: pass errors from pci_set_vga_state() up

[Claude Code Review Bot <claude-review@example.com>]

Patch Review

**Verdict: Correct but has a concern.**

The approach of wrapping the error in `ERR_PTR()` to fit the existing pointer return type of `__vga_tryget()` is reasonable. The `vga_get()` caller is properly updated with `IS_ERR()`/`PTR_ERR()` checks.

However, there is a missed caller: `vga_tryget()` at `drivers/pci/vgaarb.c:529`:

```c
if (__vga_tryget(vgadev, rsrc))
    rc = -EBUSY;
```

After this patch, `__vga_tryget()` can return `ERR_PTR(-EIO)` (or other error pointers). Since `ERR_PTR()` returns a non-NULL pointer, this truthiness check won't crash — it correctly enters the error branch. But it will unconditionally report `-EBUSY` instead of the actual error code (e.g., `-EIO`). This masks the real failure reason. It should be updated to something like:

```c
conflict = __vga_tryget(vgadev, rsrc);
if (IS_ERR(conflict))
    rc = PTR_ERR(conflict);
else if (conflict)
    rc = -EBUSY;
```

**State inconsistency concern:** When `pci_set_vga_state()` fails while disabling a conflicting device (line 311-313), the function returns immediately. At this point, earlier conflicting devices in the loop iteration may have already had their VGA state disabled and their `owns` bits cleared (line 314). When the error propagates up and `vga_get()` breaks out of its loop, no rollback occurs — those previously-disabled conflicts remain disabled with no owner. This is arguably acceptable since the alternative (complex rollback logic) is fragile, and the VGA arbiter state may self-correct on the next successful `vga_get()`. But it's worth the author considering whether a `dev_warn()` or similar diagnostic would be appropriate when this happens.

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Generated by Claude Code Patch Reviewer