|WARNING| common/cnxk: fix duplicate mbox alloc in NPA aura pool init

[dpdklab at iol.unh.edu]

Test-Label: ai-code-review
Test-Status: WARNING
https://dpdk.org/patch/169091

_AI Code Review_

=== Patch Review: series.patch (via Claude) ===
Review date: 2026-09-04

# DPDK Patch Review

## Summary
This patch fixes a critical double-allocation bug in `npa_aura_pool_init()` that was introduced when CN20K support was added. The duplicate allocation causes the first (correctly initialized) mbox message to be orphaned, while an uninitialized message is sent to the AF firmware.

---

## Errors

### 1. Resource Leak (Correctness Bug)
**File**: drivers/common/cnxk/roc_npa.c  
**Lines**: 106-113 (before patch)

The code allocates a mbox message twice without freeing the first allocation:
```c
if (roc_model_is_cn20k()) {
    pool_init_req = mbox_alloc_msg_npa_pool_aq_enq(mbox);
} else {
    pool_init_req = mbox_alloc_msg_npa_aq_enq(mbox);
}
pool_init_req = mbox_alloc_msg_npa_aq_enq(mbox);  /* LEAK: overwrites pointer */
```

The first allocated message (from line 106-110) is never freed and becomes unreachable when `pool_init_req` is overwritten at line 112. This leaks mbox resources on every call to `npa_aura_pool_init()`.

**Impact**: Memory leak in mbox message pool; repeated calls will exhaust available mbox slots.

**Fix**: The patch correctly removes the duplicate allocation at line 112.

---

## Warnings

None identified. The patch is minimal and correct.

---

## Info

### Positive Observations

1. **Correct fix**: Removing the duplicate allocation is the right approach rather than trying to free the first message, since the model-specific allocation should be the only one.

2. **Good commit message**: Clearly explains:
   - What the bug is (duplicate allocation)
   - Why it matters (orphaned message with uninitialized fields sent to AF)
   - On which platforms it occurs (non-CN20K)
   - The root cause (line 112 not removed when model-specific branch added)

3. **Proper tags**: Includes `Fixes:` with the commit that introduced the bug, `Cc: stable at dpdk.org` for backport, and original author Cc.

4. **Minimal scope**: One-line deletion, no unnecessary changes.

---

## Conclusion

**Verdict**: The patch correctly fixes a resource leak and undefined behavior bug. No style, API, or documentation issues identified. The fix is appropriate for stable backport.

**Recommendation**: Accept after standard review process (maintainer ack, CI validation).