Claude review: drm/drm_ras: Add clear-error-counter netlink command to drm_ras

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

Patch Review

**Overall**: Solid implementation that mirrors the existing `get-error-counter` doit pattern. The YAML anchor usage to avoid duplicating the attribute list is a nice touch.

**Error code for missing callback**: In `drm_ras_nl_clear_error_counter_doit()`:

```c
	node = xa_load(&drm_ras_xa, node_id);
	if (!node || !node->clear_error_counter)
		return -ENOENT;
```

When the node exists but the driver hasn't implemented `clear_error_counter`, returning `-ENOENT` is misleading — the node *was* found. Consider returning `-EOPNOTSUPP` (or `-ENOTSUPP`) for the missing-callback case, and `-ENOENT` only for the node-not-found case. This would give userspace a meaningful distinction:

```c
	node = xa_load(&drm_ras_xa, node_id);
	if (!node)
		return -ENOENT;
	if (!node->clear_error_counter)
		return -EOPNOTSUPP;
```

This is consistent with how other kernel subsystems signal "operation not supported by this driver." The existing `get_node_error_counter()` has the same conflation of the two cases (`!node || !node->query_error_counter`), but since `query_error_counter` is effectively mandatory for any registered node, it's less of a practical issue there. For `clear_error_counter`, which is explicitly optional, the distinction matters more.

**Pre-existing leak in `doit_reply_value()`** (not introduced by this patch, just noting): At line ~202-205 of the existing code, if `get_node_error_counter()` fails, `msg` is leaked:

```c
	msg = genlmsg_new(NLMSG_GOODSIZE, GFP_KERNEL);
	...
	ret = get_node_error_counter(node_id, error_id, &error_name, &value);
	if (ret)
		return ret;  /* msg leaked */
```

Not blocking for this series, but worth a separate fix.

**Everything else looks correct**:
- The YAML spec properly uses an anchor `&id-attrs` on the `get-error-counter` request attributes and references it with `*id-attrs` in `clear-error-counter`. Clean.
- The NLA policy correctly requires both `NODE_ID` and `ERROR_ID` as `NLA_U32`.
- The genl_split_ops entry correctly uses `GENL_ADMIN_PERM | GENL_CMD_CAP_DO` — admin-only, doit-only (no dump), which is appropriate for a destructive/write operation.
- The `clear_error_counter` callback in `struct drm_ras_node` is well-documented and has the right signature.
- The range check mirrors `get_node_error_counter()` exactly, which is good.

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Generated by Claude Code Patch Reviewer