[PATCH v2] net/bnxt: add Tx DMA error stat counter

[Stephen Hemminger]

On Sun, 20 Sep 2026 20:27:03 -0600
Mohammad Shuab Siddique <mohammad-shuab.siddique at broadcom.com> wrote:

> From: Mohammad Shuab Siddique <mohammad-shuab.siddique at broadcom.com>
> 
> Hardware already reports an invalid/bad DMA address on a Tx BD via
> the TX_CMPL_ERRORS_DMA_ERROR bit in the Tx completion record, but the
> driver never inspected it, so a bad mbuf->buf_iova on Tx completed
> silently with no visibility.
> 
> Check the bit in bnxt_handle_tx_cp() and in the AVX2/SSE vector
> Tx-completion handlers, and count occurrences in a new per-queue
> tx_dma_err counter. The counter is folded into the standard oerrors
> stat and also exposed as a named xstat (tx_dma_err_pkts) for
> finer-grained visibility.
> 
> Signed-off-by: Mohammad Shuab Siddique <mohammad-shuab.siddique at broadcom.com>
> ---

[PATCH v2] net/bnxt: add Tx DMA error stat counter

Warning: tx_dma_err is a per-queue, single-writer counter but uses
rte_atomic_fetch_add_explicit() in the completion fast path. That is
a locked RMW for no benefit. Use a plain increment. The existing
tx_mbuf_drop pattern is not a reason to extend it.

Warning: bnxt_handle_tx_cp_vec() in bnxt_rxtx_vec_neon.c is not
updated. arm64 never counts DMA errors.

Warning: the release note says "per-queue xstat", but the patch
exposes a single port-wide sum. Fix one or the other.

Info: "tx_dma_err_pkts" counts completions, not packets. Vector
completions cover opaque packets, and with the following coalescing
patch one completion covers many. Rename the xstat or count packets.