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[78.2.18.104]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-c260d52dbc7sm142564066b.29.2026.09.04.11.37.37 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 04 Sep 2026 11:37:38 -0700 (PDT) From: Dmitry Sinyavin To: Stephan Gerhold Cc: Dmitry Sinyavin , Stephan Gerhold , Loic Poulain , Sergey Ryazanov , Johannes Berg , Andrew Lunn , "David S . Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , linux-arm-msm@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH net v4] net: wwan: qcom_bam_dmux: account network packets Date: Fri, 4 Sep 2026 20:37:37 +0200 Message-ID: <20260904183737.2994139-1-sinyavin@gmail.com> X-Mailer: git-send-email 2.53.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit The BAM-DMUX data path does not update the network device packet and byte counters. As a result, userspace sees zero traffic even while packets are being transferred. Use the standard per-CPU software statistics helpers. Account transmitted packets after the driver has prepared and accepted them, before returning NETDEV_TX_OK. The asynchronous DMA completion may run after the network device has been unregistered. Account received packets after removing the BAM-DMUX header and padding. Fixes: 21a0ffd9b38c ("net: wwan: Add Qualcomm BAM-DMUX WWAN network driver") Signed-off-by: Dmitry Sinyavin --- v4: - Move TX accounting from the asynchronous DMA completion to the transmit path, avoiding access to statistics after netdev unregistration. v3: - Count packets discarded by the transmit error path. v2: - Read the TX payload length after unmapping the DMA buffer and combine the network-device checks. v3: https://lore.kernel.org/netdev/20260902124506.363174-1-sinyavin@gmail.com/ v2: https://lore.kernel.org/netdev/20260831181006.1382372-1-sinyavin@gmail.com/ v1: https://lore.kernel.org/netdev/20260830085400.2542956-1-sinyavin@gmail.com/ Build-tested for ARM with Clang and W=1 using allmodconfig and allyesconfig. Tested on a ZTE MF283V with an MDM9607. The modem registered on LTE and three 32-byte ICMP echo requests increased both wwan0 RX and TX counters by three packets and 180 bytes. Bringing the interface down afterwards produced no DMA, BAM-DMUX, or kernel fault messages. drivers/net/wwan/qcom_bam_dmux.c | 16 +++++++++++----- 1 file changed, 11 insertions(+), 5 deletions(-) diff --git a/drivers/net/wwan/qcom_bam_dmux.c b/drivers/net/wwan/qcom_bam_dmux.c index cc6ace8d6437..03360301c8ee 100644 --- a/drivers/net/wwan/qcom_bam_dmux.c +++ b/drivers/net/wwan/qcom_bam_dmux.c @@ -335,6 +335,7 @@ static netdev_tx_t bam_dmux_netdev_start_xmit(struct sk_buff *skb, struct bam_dmux_netdev *bndev = netdev_priv(netdev); struct bam_dmux *dmux = bndev->dmux; struct bam_dmux_skb_dma *skb_dma; + unsigned int len = skb->len; int active, ret; skb_dma = bam_dmux_tx_queue(dmux, skb); @@ -357,17 +358,19 @@ static netdev_tx_t bam_dmux_netdev_start_xmit(struct sk_buff *skb, if (!atomic_long_fetch_or(BIT(skb_dma - dmux->tx_skbs), &dmux->tx_deferred_skb)) queue_pm_work(&dmux->tx_wakeup_work); - return NETDEV_TX_OK; - } + } else { + if (!bam_dmux_skb_dma_submit_tx(skb_dma)) + goto drop; - if (!bam_dmux_skb_dma_submit_tx(skb_dma)) - goto drop; + dma_async_issue_pending(dmux->tx); + } - dma_async_issue_pending(dmux->tx); + dev_sw_netstats_tx_add(netdev, 1, len); return NETDEV_TX_OK; drop: bam_dmux_tx_done(skb_dma); + dev_core_stats_tx_dropped_inc(netdev); dev_kfree_skb_any(skb); return NETDEV_TX_OK; } @@ -402,6 +405,7 @@ static const struct net_device_ops bam_dmux_ops = { .ndo_open = bam_dmux_netdev_open, .ndo_stop = bam_dmux_netdev_stop, .ndo_start_xmit = bam_dmux_netdev_start_xmit, + .ndo_get_stats64 = dev_get_tstats64, }; static const struct device_type wwan_type = { @@ -421,6 +425,7 @@ static void bam_dmux_netdev_setup(struct net_device *dev) dev->needed_headroom = sizeof(struct bam_dmux_hdr); dev->needed_tailroom = sizeof(u32); /* word-aligned */ dev->tx_queue_len = DEFAULT_TX_QUEUE_LEN; + dev->pcpu_stat_type = NETDEV_PCPU_STAT_TSTATS; /* This perm addr will be used as interface identifier by IPv6 */ dev->addr_assign_type = NET_ADDR_RANDOM; @@ -533,6 +538,7 @@ static void bam_dmux_cmd_data(struct bam_dmux_skb_dma *skb_dma) break; } + dev_sw_netstats_rx_add(netdev, skb->len); netif_receive_skb(skb); } base-commit: 2188569e7e1b0bc3f3b557dc97ab7a02befc11c8 -- 2.53.0