a boolean. I like that the most, but perhaps some ancient, not-really-networking protocol would suffer. 3) make TCP ignore the errors It is not entirely clear to me what benefit TCP gets from interpreting the result of ip_queue_xmit()? Specifically once the connection is established and we're pushing data - packet loss is just packet loss? 4) this fix Ignore the rc in the Qdisc-less+GSO case, since it's unreliable. We already always return OK in the TCQ_F_CAN_BYPASS case. In the Qdisc-less case let's be a bit more conservative and only mask the GSO errors. This path is taken by non-IP-"networks" like CAN, MCTP etc, so we could regress some ancient thing. This is the simplest, but also maybe the hackiest fix? Similar fix has been proposed by Eric in the past but never committed because original reporter was working with an OOT driver and wasn't providing feedback (see Link). Link: https://lore.kernel.org/CANn89iJcLepEin7EtBETrZ36bjoD9LrR=k4cfwWh046GB+4f9A@mail.gmail.com Fixes: 1f59533f9ca5 ("qdisc: validate frames going through the direct_xmit path") Signed-off-by: Jakub Kicinski Reviewed-by: Eric Dumazet Link: https://patch.msgid.link/20260223235100.108939-1-kuba@kernel.org Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin --- net/core/dev.c | 23 ++++++++++++++++++----- 1 file changed, 18 insertions(+), 5 deletions(-) diff --git a/net/core/dev.c b/net/core/dev.c index 60a26208cbd87..062415cc3e5a4 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -4818,6 +4818,8 @@ int __dev_queue_xmit(struct sk_buff *skb, struct net_device *sb_dev) * to -1 or to their cpu id, but not to our id. */ if (READ_ONCE(txq->xmit_lock_owner) != cpu) { + bool is_list = false; + if (dev_xmit_recursion()) goto recursion_alert; @@ -4828,17 +4830,28 @@ int __dev_queue_xmit(struct sk_buff *skb, struct net_device *sb_dev) HARD_TX_LOCK(dev, txq, cpu); if (!netif_xmit_stopped(txq)) { + is_list = !!skb->next; + dev_xmit_recursion_inc(); skb = dev_hard_start_xmit(skb, dev, txq, &rc); dev_xmit_recursion_dec(); - if (dev_xmit_complete(rc)) { - HARD_TX_UNLOCK(dev, txq); - goto out; - } + + /* GSO segments a single SKB into + * a list of frames. TCP expects error + * to mean none of the data was sent. + */ + if (is_list) + rc = NETDEV_TX_OK; } HARD_TX_UNLOCK(dev, txq); + if (!skb) /* xmit completed */ + goto out; + net_crit_ratelimited("Virtual device %s asks to queue packet!\n", dev->name); + /* NETDEV_TX_BUSY or queue was stopped */ + if (!is_list) + rc = -ENETDOWN; } else { /* Recursion is detected! It is possible, * unfortunately @@ -4846,10 +4859,10 @@ int __dev_queue_xmit(struct sk_buff *skb, struct net_device *sb_dev) recursion_alert: net_crit_ratelimited("Dead loop on virtual device %s, fix it urgently!\n", dev->name); + rc = -ENETDOWN; } } - rc = -ENETDOWN; rcu_read_unlock_bh(); dev_core_stats_tx_dropped_inc(dev); -- 2.51.0[PATCH 6.19 501/844] net: consume xmit errors of GSO framesSasha Levin undefinedlinux-kernel@vger.kernel.org, stable@vger.kernel.org undefined undefined undefined undefined undefinedĄd†§{