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authorLoic Poulain <loic.poulain@linaro.org>2021-02-04 09:40:00 +0100
committerJakub Kicinski <kuba@kernel.org>2021-02-06 20:28:45 +0100
commitc1fcda2bdfd04179dbc81320a24baa539b476281 (patch)
treeccd182e7cab27ae99bfe73823a491c570ac55d65 /drivers/net/mhi_net.c
parentnet: qualcomm: rmnet: Fix rx_handler for non-linear skbs (diff)
downloadlinux-c1fcda2bdfd04179dbc81320a24baa539b476281.tar.xz
linux-c1fcda2bdfd04179dbc81320a24baa539b476281.zip
net: mhi-net: Add re-aggregation of fragmented packets
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 <loic.poulain@linaro.org> Acked-by: Jesse Brandeburg <jesse.brandeburg@intel.com> Link: https://lore.kernel.org/r/1612428002-12333-1-git-send-email-loic.poulain@linaro.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'drivers/net/mhi_net.c')
-rw-r--r--drivers/net/mhi_net.c74
1 files changed, 64 insertions, 10 deletions
diff --git a/drivers/net/mhi_net.c b/drivers/net/mhi_net.c
index 4f512531b7d0..880099193734 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);
}