|WARNING| net/mana: fix Tx stall from send queue free-space unit mismatch

[dpdklab at iol.unh.edu]

Test-Label: ai-code-review
Test-Status: WARNING
https://dpdk.org/patch/169521

_AI Code Review_

=== Patch Review: series.patch (via Claude) ===
Review date: 2026-09-14

# DPDK Patch Review

## Summary
This patch fixes a unit mismatch bug in the MANA driver's send queue accounting that causes premature -EBUSY returns. The fix is correct and well-explained.

---

## Correctness Review

**No correctness bugs found.**

The patch correctly identifies and fixes a unit mismatch:
- **Before**: `queue->count - (queue->head - queue->tail)` mixed entry count with WQE unit count
- **After**: `queue->size / GDMA_WQE_ALIGNMENT_UNIT_SIZE - (queue->head - queue->tail)` uses consistent WQE units

The change is safe: `queue->size` is already validated during queue setup, and the division by `GDMA_WQE_ALIGNMENT_UNIT_SIZE` (a compile-time constant power-of-two) cannot overflow or produce incorrect results.

---

## C Coding Style

### Error: Multi-line comment style violation

The added comment uses incorrect formatting:

```c
/* head/tail count WQE alignment units, so the capacity they are compared
 * against must too: queue->count is in entries and undercounts the
 * queue, stalling Tx well below capacity.
 */
```

**Fix**: DPDK requires asterisks aligned on continuation lines:

```c
/*
 * head/tail count WQE alignment units, so the capacity they are compared
 * against must too: queue->count is in entries and undercounts the
 * queue, stalling Tx well below capacity.
 */
```

>From AGENTS.md:
```c
/*
 * Multi-line comments look like this. Make them real sentences. Fill
 * them so they look like real paragraphs.
 */
```

---

## API and Documentation

**No issues.** This is an internal driver fix with no API impact. Release notes are not required (internal correctness fix in a single driver).

---

## Final Recommendation

**Accept with style fix.** The patch solves a real correctness bug (Tx stall) with the right approach. Only the comment formatting needs adjustment before merge.