Claude review: drm/exec: Make the drm_exec_until_all_locked() macro more readable

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

Patch Review

**Assessment: Good.**

```c
#define __drm_exec_until_all_locked(exec, _label)			 \
_label:									 \
	for (void *const __maybe_unused __drm_exec_retry_ptr = &&_label; \
	     drm_exec_cleanup(exec);)
```

Three improvements here:
1. `__UNIQUE_ID` for the label name instead of `__PASTE(__drm_exec_, __LINE__)` — consistent with patch 1 and standard kernel idiom.
2. `__maybe_unused` instead of `(void)__drm_exec_retry_ptr` cast — cleaner.
3. `void *const` — prevents accidental reassignment of the jump target.

Note that `__drm_exec_retry_ptr` itself is deliberately *not* uniquified, since `drm_exec_retry_on_contention()` (and the new `drm_exec_retry()` from patch 3) reference it by name. This is the correct design — the variable name forms the contract between the loop macro and the retry macros.

One minor observation: the comment block is moved from the `drm_exec_until_all_locked` kdoc to the helper, which is appropriate since the implementation detail about label scoping belongs with the helper.

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Generated by Claude Code Patch Reviewer