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[174.29.1.49]) by smtp.gmail.com with ESMTPSA id 586e51a60fabf-4a6df871f44sm596045fac.1.2026.10.13.13.35.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 13 Oct 2026 13:35:45 -0700 (PDT) From: James Hilliard Date: Tue, 13 Oct 2026 14:35:42 -0600 Subject: [PATCH net] net: stmmac: avoid duplicate XSK TX completions Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20261013-submit-stmmac-xsk-tx-completion-v1-v1-1-f21b9d098e62@gmail.com> X-B4-Tracking: v=1; b=H4sIAAAAAAAC/yWN0QrCMAxFf2Xk2UA7YU5/RXzoaqZR240mjsLYv xv18Ry4564gVJgETs0KhRYWnrKB3zUQ7yHfCPlqDK1rO++cR3kPiRVFUwoRqzxRK8YpzS9S2+L ise8PnRvDcfBuDxaaC41cfydnyKRw+UtLPSjqNw/b9gFVMlp9iwAAAA== X-Change-ID: 20261001-submit-stmmac-xsk-tx-completion-v1-88760fa9b103 To: Maxime Chevallier , Andrew Lunn , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Maxime Coquelin , Alexandre Torgue , Ong Boon Leong Cc: netdev@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Magnus Karlsson , Maciej Fijalkowski , Stanislav Fomichev , bpf@vger.kernel.org, James Hilliard X-Mailer: b4 0.15.2 stmmac_tx_clean() reports completed AF_XDP TX descriptors through xsk_tx_completed(), but leaves their buffer type as STMMAC_TXBUF_T_XSK_TX. The slots retain that type until they are reused for another buffer type. On interface close or XDP teardown, dma_free_tx_skbufs() walks the entire TX ring, not just the dirty_tx..cur_tx range. stmmac_free_tx_buffer() counts the stale XSK_TX slots again, causing xsk_tx_completed() to advance the completion-ring producer for buffers that have already been returned. This publishes completion entries without matching outstanding TX reservations and corrupts completion accounting for a socket which stays bound across the teardown. Reset the XSK buffer type after counting the completion in both stmmac_tx_clean() and stmmac_free_tx_buffer(). XSK TX slots have a NULL skb pointer and no per-slot DMA mapping, so the SKB type represents an empty slot. Pending XSK descriptors keep their type until they are completed or released, and a released slot can no longer be counted again by a later cleanup. Fixes: 132c32ee5bc0 ("net: stmmac: Add TX via XDP zero-copy socket") Signed-off-by: James Hilliard --- Assisted-by: Codex:gpt-6-astra --- drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/ne= t/ethernet/stmicro/stmmac/stmmac_main.c index b837e8e27a35..1527e03711cc 100644 --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c @@ -1742,8 +1742,10 @@ static void stmmac_free_tx_buffer(struct stmmac_priv= *priv, tx_q->xdpf[i] =3D NULL; } =20 - if (tx_q->tx_skbuff_dma[i].buf_type =3D=3D STMMAC_TXBUF_T_XSK_TX) + if (tx_q->tx_skbuff_dma[i].buf_type =3D=3D STMMAC_TXBUF_T_XSK_TX) { tx_q->xsk_frames_done++; + tx_q->tx_skbuff_dma[i].buf_type =3D STMMAC_TXBUF_T_SKB; + } =20 if (tx_q->tx_skbuff[i] && tx_q->tx_skbuff_dma[i].buf_type =3D=3D STMMAC_TXBUF_T_SKB) { @@ -2926,8 +2928,11 @@ static int stmmac_tx_clean(struct stmmac_priv *priv,= int budget, u32 queue, tx_q->xdpf[entry] =3D NULL; } =20 - if (tx_q->tx_skbuff_dma[entry].buf_type =3D=3D STMMAC_TXBUF_T_XSK_TX) + if (tx_q->tx_skbuff_dma[entry].buf_type =3D=3D STMMAC_TXBUF_T_XSK_TX) { tx_q->xsk_frames_done++; + /* Teardown must not count this slot again. */ + tx_q->tx_skbuff_dma[entry].buf_type =3D STMMAC_TXBUF_T_SKB; + } =20 if (tx_q->tx_skbuff_dma[entry].buf_type =3D=3D STMMAC_TXBUF_T_SKB) { if (likely(skb)) { --- base-commit: 513444cc62e231a11c9b15ea88de0890da9b2b4f change-id: 20261001-submit-stmmac-xsk-tx-completion-v1-88760fa9b103 Best regards, -- =20 James Hilliard