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[78.2.9.45]) by smtp.gmail.com with ESMTPSA id 4fb4d7f45d1cf-6a67f952c1bsm2043758a12.26.2026.09.03.01.27.15 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 03 Sep 2026 01:27:16 -0700 (PDT) Message-ID: Date: Thu, 3 Sep 2026 10:27:15 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH net v3] net: wwan: qcom_bam_dmux: account network packets To: Stephan Gerhold Cc: 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 References: <20260902124506.363174-1-sinyavin@gmail.com> Content-Language: en-US From: Dmitry Sinyavin In-Reply-To: <20260902124506.363174-1-sinyavin@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit The delayed Sashiko review of v2 identified a valid teardown race that also affects v3. I will address it in v4. pw-bot: changes-requested 02.09.2026 14:45, Dmitry Sinyavin wrote: > 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 their DMA completion and 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 > Reviewed-by: Loic Poulain > --- > 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. > > 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. > Hardware-tested on an MDM9607-based device: three 32-byte ICMP probes completed > without loss, and the RX and TX counters each advanced by three packets and > 180 bytes. > > drivers/net/wwan/qcom_bam_dmux.c | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/drivers/net/wwan/qcom_bam_dmux.c b/drivers/net/wwan/qcom_bam_dmux.c > index cc6ace8d6437..ef3356200b3e 100644 > --- a/drivers/net/wwan/qcom_bam_dmux.c > +++ b/drivers/net/wwan/qcom_bam_dmux.c > @@ -177,8 +177,12 @@ static void bam_dmux_tx_callback(void *data) > { > struct bam_dmux_skb_dma *skb_dma = data; > struct sk_buff *skb = skb_dma->skb; > + struct net_device *netdev = skb->dev; > > bam_dmux_tx_done(skb_dma); > + if (netdev) > + dev_sw_netstats_tx_add(netdev, 1, > + ((struct bam_dmux_hdr *)skb->data)->len); > dev_consume_skb_any(skb); > } > > @@ -368,6 +372,7 @@ static netdev_tx_t bam_dmux_netdev_start_xmit(struct sk_buff *skb, > > 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 +407,7 @@ 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 +427,7 @@ 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 +540,7 @@ 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