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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Felix Fietkau , linux-kernel@vger.kernel.org (open list) Subject: [PATCH net] net: bgmac: fix TX DMA unmapping on fragment mapping failure Date: Sun, 18 Oct 2026 16:13:48 -0700 Message-ID: <20261018231348.36884-1-rosenp@gmail.com> X-Mailer: git-send-email 2.56.0 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit When mapping a fragment fails, bgmac_dma_tx_add() unwinds with the wrong slots. It passes the failed fragment's slot->dma_addr, which holds the mapping error, to dma_unmap_single() for the head. The fragment loop indexes from ring->end instead of ring->end + 1, so it unmaps the head a second time as a page and leaves the last mapped fragment mapped. None of the affected slots get their dma_addr cleared either, which includes the head slot when mapping the head fails. bgmac_dma_tx_ring_free() unmaps every slot with a non-zero dma_addr, so tearing down the ring unmaps these addresses again. Unmap the head and each mapped fragment from their own slots, and clear dma_addr on every slot the failed packet touched. Fixes: 9cde94506eac ("bgmac: implement scatter/gather support") Signed-off-by: Rosen Penev --- drivers/net/ethernet/broadcom/bgmac.c | 21 +++++++++++++-------- 1 file changed, 13 insertions(+), 8 deletions(-) diff --git a/drivers/net/ethernet/broadcom/bgmac.c b/drivers/net/ethernet/broadcom/bgmac.c index 1835266fdd09..134eff89f787 100644 --- a/drivers/net/ethernet/broadcom/bgmac.c +++ b/drivers/net/ethernet/broadcom/bgmac.c @@ -208,19 +208,24 @@ static netdev_tx_t bgmac_dma_tx_add(struct bgmac *bgmac, return NETDEV_TX_OK; err_dma: - dma_unmap_single(dma_dev, slot->dma_addr, skb_headlen(skb), - DMA_TO_DEVICE); + slot->dma_addr = 0; while (i-- > 0) { - int index = (ring->end + i) % BGMAC_TX_RING_SLOTS; - struct bgmac_slot_info *slot = &ring->slots[index]; - u32 ctl1 = le32_to_cpu(ring->cpu_base[index].ctl1); - int len = ctl1 & BGMAC_DESC_CTL1_LEN; - - dma_unmap_page(dma_dev, slot->dma_addr, len, DMA_TO_DEVICE); + index = (ring->end + 1 + i) % BGMAC_TX_RING_SLOTS; + slot = &ring->slots[index]; + dma_unmap_page(dma_dev, slot->dma_addr, + skb_frag_size(&skb_shinfo(skb)->frags[i]), + DMA_TO_DEVICE); + slot->dma_addr = 0; } + slot = &ring->slots[ring->end % BGMAC_TX_RING_SLOTS]; + dma_unmap_single(dma_dev, slot->dma_addr, skb_headlen(skb), + DMA_TO_DEVICE); + err_dma_head: + slot->dma_addr = 0; + netdev_err(bgmac->net_dev, "Mapping error of skb on ring 0x%X\n", ring->mmio_base); -- 2.56.0