Claude review: drm/i915: Remove drm_dev_unregister() from the error path during i915_driver_register()

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

Patch Review

**Verdict: Looks good.**

The commit message accurately describes the problem and the fix. I verified each claim:

1. **`drm_dev_register()` cleans up after itself on failure.** Confirmed in `drm_drv.c:1115-1123` — on error, `drm_dev_register()` jumps to `err_minors` which calls `remove_compat_control_link()`, `drm_minor_unregister()` for all three minor types, then returns the error. So calling `drm_dev_unregister()` after a failed `drm_dev_register()` is indeed double-cleanup.

2. **`drm_client_sysrq_register()` is only called on success.** Confirmed at `drm_drv.c:1105` — `drm_client_sysrq_register(dev)` is called just before the success return, after both `err_unload` and `err_minors` labels. If `drm_dev_register()` fails, this call never executes.

3. **`drm_client_sysrq_unregister()` triggers a WARN_ON.** Confirmed at `drm_client_sysrq.c:58` — `drm_client_sysrq_unregister()` does `drm_WARN_ON(dev, list_empty(&dev->client_sysrq_list))`. Since `drm_client_sysrq_register()` was never called, the list head is in its initialized (empty) state, triggering the warning.

4. **The remaining error path is correct.** After removing the `drm_dev_unregister()` call, the error path at `i915_driver.c:639-645` still correctly unwinds `i915_pmu_register()` and `i915_gem_driver_register()` which were called earlier in the function at lines 632-633. The `intel_vgpu_register()` at line 635 does not appear to have an unregister counterpart needed in this path (it's a no-op on non-VF), so the cleanup sequence is correct.

5. **Additionally, `drm_dev_unregister()` does more than just undo `drm_dev_register()`** — it also calls `drm_client_dev_unregister()`, `drm_modeset_unregister_all()`, and `drm_debugfs_dev_fini()` (`drm_drv.c:1146-1166`). Calling these when their corresponding register functions were never called (because `drm_dev_register()` failed) is wrong and could cause further issues beyond the WARN_ON.

No concerns with this patch. 

Reviewed-by is warranted.

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Generated by Claude Code Patch Reviewer