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[23.128.96.18]) by mx.google.com with ESMTP id n3si12832662ejh.49.2021.02.02.08.12.03; Tue, 02 Feb 2021 08:12:03 -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=O4nU54pI; 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 S236130AbhBBQL1 (ORCPT + 7 others); Tue, 2 Feb 2021 11:11:27 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48792 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236104AbhBBQJK (ORCPT ); Tue, 2 Feb 2021 11:09:10 -0500 Received: from mail-wm1-x32f.google.com (mail-wm1-x32f.google.com [IPv6:2a00:1450:4864:20::32f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 51F01C0613D6 for ; Tue, 2 Feb 2021 08:08:29 -0800 (PST) Received: by mail-wm1-x32f.google.com with SMTP id e15so2799625wme.0 for ; Tue, 02 Feb 2021 08:08:29 -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=I72tFhBGRzGArbTD6liOesUdXAfRQUF4SchJqYsqSSM=; b=O4nU54pILwA7XAPfd5F+ifqTrR/mODJtHpYiPNUe9lHg2joI+6OzA06BERZIGwPr/Z 9+MQWKjRnXVXe03S5lF3yRUReiiyBC+qhrZ9jJacIAYqnzsQzejvDXzza1EqFsA2txPf SMIIUw50ntFy0gzYFCyhaMCo1gSU6oukmZUcGabyQSoz7C+TE8jY0E/UCKRN7E08pzST c29VV7SC6mFuX2SnMukM/+L0GMFEu/q4tYqD9HACOI4RmzXuuCuvKAcQxEbfyo/y/VgY R1LcIYhl2+U33LzkuGma5gIXAWtKKlDBBiQSVZt8UMUT3F5YJH1rx3moRlGaMo0KOtOT 4P7A== 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=I72tFhBGRzGArbTD6liOesUdXAfRQUF4SchJqYsqSSM=; b=oflGmOgs5sY05l5lMC0x9FE4109k+XCZte57OBW+Y9aLFkMb1uzFmNrownOhFu3lVO Qf6yxwgqwb7MEk4ywKaY5a4IZqYT6+8KHFsC51bHv+A2TSW/OTeCZ1jy1wHx88Nzguw3 hazQum9D4frROeX2Fgvw0Tm1EKehWYBw4wMOqGz+dlWk/w3yhGuEDBJn94uiOAJWH5pO L9jNieCvbvLHbWJKUtKDeIwck7H0OjYQ7CogkcTog3VSKCGYUMUomALd72ZZtMXSDxOg Ocj+sn9WbP6FGmM+I+CdPIRXxFCQSXpc2fJWt6qcfcAxiUmhYuWP63FV5vHWD3kn5I5g BwsA== X-Gm-Message-State: AOAM533wzSgYjULLy6Gu9oDxu1MSYyXjibDsOAlq2rZRFRiF8UzB/y4s ziLL3rkir/ICPJwW8sFnTAF1Rg== X-Received: by 2002:a1c:408a:: with SMTP id n132mr4273380wma.86.1612282107920; Tue, 02 Feb 2021 08:08:27 -0800 (PST) Received: from localhost.localdomain ([88.122.66.28]) by smtp.gmail.com with ESMTPSA id y6sm3900491wma.19.2021.02.02.08.08.26 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Tue, 02 Feb 2021 08:08:27 -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 v2 1/2] net: mhi-net: Add de-aggeration support Date: Tue, 2 Feb 2021 17:16:07 +0100 Message-Id: <1612282568-14094-1-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 previoulsy 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. drivers/net/mhi_net.c | 79 ++++++++++++++++++++++++++++++++++++++++++++------- 1 file changed, 69 insertions(+), 10 deletions(-) -- 2.7.4 diff --git a/drivers/net/mhi_net.c b/drivers/net/mhi_net.c index 4f512531..be39779 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 +134,37 @@ 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; + + /* data_len is normally the size of paged data, in our case there is no + * paged data (nr_frags = 0), so it represents the size of chained skbs, + * This way, net core will consider skb->frag_list. + */ + 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 +175,42 @@ 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 +225,6 @@ static void mhi_net_dl_callback(struct mhi_device *mhi_dev, break; } - skb_put(skb, mhi_res->bytes_xferd); netif_rx(skb); } @@ -267,6 +322,7 @@ 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 +357,9 @@ 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); }