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[23.128.96.18]) by mx.google.com with ESMTP id r11si1203343edh.225.2021.02.03.05.15.09; Wed, 03 Feb 2021 05:15:10 -0800 (PST) Received-SPF: pass (google.com: domain of netdev-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; dkim=pass header.i=@linaro.org header.s=google header.b=FQXZReHE; spf=pass (google.com: domain of netdev-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=netdev-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=linaro.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231535AbhBCNOX (ORCPT + 7 others); Wed, 3 Feb 2021 08:14:23 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38948 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229979AbhBCNOQ (ORCPT ); Wed, 3 Feb 2021 08:14:16 -0500 Received: from mail-wm1-x32e.google.com (mail-wm1-x32e.google.com [IPv6:2a00:1450:4864:20::32e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 178DAC0613D6 for ; Wed, 3 Feb 2021 05:13:36 -0800 (PST) Received: by mail-wm1-x32e.google.com with SMTP id m1so5189215wml.2 for ; Wed, 03 Feb 2021 05:13:36 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=from:to:cc:subject:date:message-id; bh=f60+WgcNyeXJlxMaCb+V4GQ7soQ9kBKD34a4oS4TIGU=; b=FQXZReHEBQgf71+AyMQ/AvOjm1YC/ZbCiz1b0uWQadCOOd48/TpElkS8iM7/7fn03M OWjdyvI9a3JijMxN8JkRrT04sbs3Ein+svx4LvYYLkIja45S4dKWeKIjHTzWaQgXmEOt nYensxLf1yz3t6hvhFLuVzGoqi8v4U+t+62FxPyi5tTUbL7M08BzGHglIf/k1c5o9zAl Gg0hvNooNM0YxctQN4fsUPhlSXHWJHoij+P1coc3bDvgPaLd0hnxEAdtjiKJ3N4f5d9o RDayzp5i8UTt1YTWDioK32AtMpJddaz0WiW9MUbxjoEap5z9CjiB1gpzTybUCtDIeLiC wdwA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id; bh=f60+WgcNyeXJlxMaCb+V4GQ7soQ9kBKD34a4oS4TIGU=; b=UDsaS49Lm7DeT1gH+6M9gYMG2sEMYStwwrcD55RNUYTII12Dfs/yUMiVa2LgQCBPjf 6ScVxBkgrvPNWS0CgILdj093wd48bcVTFtsWsVKaMlSp+2jXPEh5dcjU0mjJbx8Oh+VL XJTSie7anq86pc+Yd2yKtA1/aEtaSay5myig4czakfowvRCTIy62P8p8+0UOithm4/hT 806DSf7uJJvtTBAM0HBlgdj2jcjhrQ8pOpp9mvm/hYxxRtPtOqP9ibZKsymFhbB9QI5N Mq47Yb6w+OlQ84U/UZ9G3eQqMpRBHhccfxDtOPww3iWwIuA4na92ygOYgkvDgw/V0Veo hV0A== X-Gm-Message-State: AOAM530kKBei6SStNYQAINJ5OL6LK1Rs3wwogUu7rY+nzeFmUesN0x3k SoCmYbL5M+wUh0YDZpAsH6tABQ== X-Received: by 2002:a1c:6a02:: with SMTP id f2mr2862448wmc.36.1612358014727; Wed, 03 Feb 2021 05:13:34 -0800 (PST) Received: from localhost.localdomain ([88.122.66.28]) by smtp.gmail.com with ESMTPSA id l14sm3852472wrq.87.2021.02.03.05.13.33 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Wed, 03 Feb 2021 05:13:34 -0800 (PST) From: Loic Poulain To: kuba@kernel.org, davem@davemloft.net Cc: willemdebruijn.kernel@gmail.com, netdev@vger.kernel.org, stranche@codeaurora.org, subashab@codeaurora.org, Loic Poulain Subject: [PATCH net-next v3 1/2] net: mhi-net: Add de-aggeration support Date: Wed, 3 Feb 2021 14:21:15 +0100 Message-Id: <1612358476-19556-1-git-send-email-loic.poulain@linaro.org> X-Mailer: git-send-email 2.7.4 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org When device side MTU is larger than host side MTU, the packets (typically rmnet packets) are split over multiple MHI transfers. In that case, fragments must be re-aggregated to recover the packet before forwarding to upper layer. A fragmented packet result in -EOVERFLOW MHI transaction status for each of its fragments, except the final one. Such transfer was previously considered as error and fragments were simply dropped. This change adds re-aggregation mechanism using skb chaining, via skb frag_list. A warning (once) is printed since this behavior usually comes from a misconfiguration of the device (e.g. modem MTU). Signed-off-by: Loic Poulain --- v2: use zero-copy skb chaining instead of skb_copy_expand. v3: Fix nit in commit msg + remove misleading inline comment for frag_list drivers/net/mhi_net.c | 74 ++++++++++++++++++++++++++++++++++++++++++++------- 1 file changed, 64 insertions(+), 10 deletions(-) -- 2.7.4 diff --git a/drivers/net/mhi_net.c b/drivers/net/mhi_net.c index 4f512531..8800991 100644 --- a/drivers/net/mhi_net.c +++ b/drivers/net/mhi_net.c @@ -32,6 +32,8 @@ struct mhi_net_stats { struct mhi_net_dev { struct mhi_device *mdev; struct net_device *ndev; + struct sk_buff *skbagg_head; + struct sk_buff *skbagg_tail; struct delayed_work rx_refill; struct mhi_net_stats stats; u32 rx_queue_sz; @@ -132,6 +134,32 @@ static void mhi_net_setup(struct net_device *ndev) ndev->tx_queue_len = 1000; } +static struct sk_buff *mhi_net_skb_agg(struct mhi_net_dev *mhi_netdev, + struct sk_buff *skb) +{ + struct sk_buff *head = mhi_netdev->skbagg_head; + struct sk_buff *tail = mhi_netdev->skbagg_tail; + + /* This is non-paged skb chaining using frag_list */ + if (!head) { + mhi_netdev->skbagg_head = skb; + return skb; + } + + if (!skb_shinfo(head)->frag_list) + skb_shinfo(head)->frag_list = skb; + else + tail->next = skb; + + head->len += skb->len; + head->data_len += skb->len; + head->truesize += skb->truesize; + + mhi_netdev->skbagg_tail = skb; + + return mhi_netdev->skbagg_head; +} + static void mhi_net_dl_callback(struct mhi_device *mhi_dev, struct mhi_result *mhi_res) { @@ -142,19 +170,42 @@ static void mhi_net_dl_callback(struct mhi_device *mhi_dev, free_desc_count = mhi_get_free_desc_count(mhi_dev, DMA_FROM_DEVICE); if (unlikely(mhi_res->transaction_status)) { - dev_kfree_skb_any(skb); - - /* MHI layer stopping/resetting the DL channel */ - if (mhi_res->transaction_status == -ENOTCONN) + switch (mhi_res->transaction_status) { + case -EOVERFLOW: + /* Packet can not fit in one MHI buffer and has been + * split over multiple MHI transfers, do re-aggregation. + * That usually means the device side MTU is larger than + * the host side MTU/MRU. Since this is not optimal, + * print a warning (once). + */ + netdev_warn_once(mhi_netdev->ndev, + "Fragmented packets received, fix MTU?\n"); + skb_put(skb, mhi_res->bytes_xferd); + mhi_net_skb_agg(mhi_netdev, skb); + break; + case -ENOTCONN: + /* MHI layer stopping/resetting the DL channel */ + dev_kfree_skb_any(skb); return; - - u64_stats_update_begin(&mhi_netdev->stats.rx_syncp); - u64_stats_inc(&mhi_netdev->stats.rx_errors); - u64_stats_update_end(&mhi_netdev->stats.rx_syncp); + default: + /* Unknown error, simply drop */ + dev_kfree_skb_any(skb); + u64_stats_update_begin(&mhi_netdev->stats.rx_syncp); + u64_stats_inc(&mhi_netdev->stats.rx_errors); + u64_stats_update_end(&mhi_netdev->stats.rx_syncp); + } } else { + skb_put(skb, mhi_res->bytes_xferd); + + if (mhi_netdev->skbagg_head) { + /* Aggregate the final fragment */ + skb = mhi_net_skb_agg(mhi_netdev, skb); + mhi_netdev->skbagg_head = NULL; + } + u64_stats_update_begin(&mhi_netdev->stats.rx_syncp); u64_stats_inc(&mhi_netdev->stats.rx_packets); - u64_stats_add(&mhi_netdev->stats.rx_bytes, mhi_res->bytes_xferd); + u64_stats_add(&mhi_netdev->stats.rx_bytes, skb->len); u64_stats_update_end(&mhi_netdev->stats.rx_syncp); switch (skb->data[0] & 0xf0) { @@ -169,7 +220,6 @@ static void mhi_net_dl_callback(struct mhi_device *mhi_dev, break; } - skb_put(skb, mhi_res->bytes_xferd); netif_rx(skb); } @@ -267,6 +317,7 @@ static int mhi_net_probe(struct mhi_device *mhi_dev, dev_set_drvdata(dev, mhi_netdev); mhi_netdev->ndev = ndev; mhi_netdev->mdev = mhi_dev; + mhi_netdev->skbagg_head = NULL; SET_NETDEV_DEV(ndev, &mhi_dev->dev); SET_NETDEV_DEVTYPE(ndev, &wwan_type); @@ -301,6 +352,9 @@ static void mhi_net_remove(struct mhi_device *mhi_dev) mhi_unprepare_from_transfer(mhi_netdev->mdev); + if (mhi_netdev->skbagg_head) + kfree_skb(mhi_netdev->skbagg_head); + free_netdev(mhi_netdev->ndev); }