Claude review: drm/buddy: Move internal helpers to buddy.c

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

Patch Review

**Overall Assessment:** This patch appropriately hides implementation details by moving unused-externally functions from the header to the source file. The claim of "no functional changes" appears accurate.

**Detailed Comments:**

#### Functions Being Made Static

```c
+static unsigned int
+gpu_buddy_block_state(struct gpu_buddy_block *block)
+{
+	return block->header & GPU_BUDDY_HEADER_STATE;
+}
```

**Good:** Reasonable to make static if only used internally.

**Code style:** Kernel style typically puts return type on same line as function name for static functions, though this appears consistent with existing code style in this file.

```c
+static bool
+gpu_buddy_block_is_allocated(struct gpu_buddy_block *block)
+{
+	return gpu_buddy_block_state(block) == GPU_BUDDY_ALLOCATED;
+}
+
+static bool
+gpu_buddy_block_is_split(struct gpu_buddy_block *block)
+{
+	return gpu_buddy_block_state(block) == GPU_BUDDY_SPLIT;
+}
```

**Good:** These are simple wrappers that were unused externally.

#### Function Being Removed

```c
-/**
- * gpu_get_buddy - get buddy address
- *
- * @block: GPU buddy block
- *
- * Returns the corresponding buddy block for @block, or NULL
- * if this is a root block and can't be merged further.
- * Requires some kind of locking to protect against
- * any concurrent allocate and free operations.
- */
-struct gpu_buddy_block *
-gpu_get_buddy(struct gpu_buddy_block *block)
-{
-	return __get_buddy(block);
-}
-EXPORT_SYMBOL(gpu_get_buddy);
```

**Critical Question:** This removes an EXPORT_SYMBOL(). Was this symbol truly unused? A simple wrapper removal seems fine, but removing an exported symbol requires verification:

1. Was this checked with `git grep gpu_get_buddy` across the entire kernel tree?
2. Are there any out-of-tree drivers that might use this?
3. Should there be a deprecation period?

**If truly unused:** Removing unused exports is good hygiene.

**If potentially used:** This would break external modules and needs coordination.

#### Function Being Kept

```c
 static inline bool
-gpu_buddy_block_is_allocated(struct gpu_buddy_block *block)
+gpu_buddy_block_is_free(struct gpu_buddy_block *block)
 {
-	return gpu_buddy_block_state(block) == GPU_BUDDY_ALLOCATED;
+	return (block->header & GPU_BUDDY_HEADER_STATE) == GPU_BUDDY_FREE;
 }
```

**From v2 changelog:** "Keep gpu_buddy_block_is_free() in header since it's now used by drm_buddy.c"

**Good:** The commit message explains why this stays in the header.

**Code change:** The implementation changed from calling `gpu_buddy_block_state()` to directly accessing the header. This is necessary since `gpu_buddy_block_state()` is now static.

**Question:** Since this is inlined and used externally, is there any performance impact from the more complex expression `(block->header & GPU_BUDDY_HEADER_STATE) == GPU_BUDDY_FREE` vs the old two-step approach? Probably not, the compiler should optimize identically.

#### Header Declaration Removal

```c
-struct gpu_buddy_block *
-gpu_get_buddy(struct gpu_buddy_block *block);
```

**Good:** Correctly removes the declaration matching the removed export.

**Summary for Patch 2:**
- The internal API cleanup is sound
- Moving internal functions to .c file is appropriate
- **Critical concern:** Need confirmation that `gpu_get_buddy()` removal won't break anything
- The `gpu_buddy_block_is_free()` handling is well-explained
- Code changes match commit message

---

## FINAL RECOMMENDATIONS

**Patch 1:**
1. Clarify what was "corrected" regarding tree index values
2. Document unused header bits 8:6 explicitly
3. Consider revising "physically contiguous" terminology
4. Minor: Clarify what "cleared/zeroed" means in GPU context

**Patch 2:**
1. **Critical:** Confirm `gpu_get_buddy()` has no users (in-tree or out-of-tree considerations)
2. Consider whether ABI compatibility concerns exist

**Series:**
- Generally well-executed cleanup
- Documentation is a valuable addition
- Code movement is appropriate
- Version 2 changes address reviewer feedback appropriately

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Generated by Claude Code Patch Reviewer