diff options
| author | Eric Dumazet <edumazet@google.com> | 2021-03-11 12:35:04 -0800 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2021-03-11 18:35:31 -0800 |
| commit | f4dae54e486d528d4dd98df116e7a522bbf12667 (patch) | |
| tree | 513a55d017f0e693e19f60f325ee82bf2cda5ccb | |
| parent | 8176f8c0f095c9df44994a33f19b55e7c847df7f (diff) | |
tcp: plug skb_still_in_host_queue() to TSQ
Jakub and Neil reported an increase of RTO timers whenever
TX completions are delayed a bit more (by increasing
NIC TX coalescing parameters)
Main issue is that TCP stack has a logic preventing a packet
being retransmit if the prior clone has not yet been
orphaned or freed.
This logic came with commit 1f3279ae0c13 ("tcp: avoid
retransmits of TCP packets hanging in host queues")
Thankfully, in the case skb_still_in_host_queue() detects
the initial clone is still in flight, it can use TSQ logic
that will eventually retry later, at the moment the clone
is freed or orphaned.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Neil Spring <ntspring@fb.com>
Reported-by: Jakub Kicinski <kuba@kernel.org>
Cc: Neal Cardwell <ncardwell@google.com>
Cc: Yuchung Cheng <ycheng@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | include/linux/skbuff.h | 2 | ||||
| -rw-r--r-- | net/ipv4/tcp_output.c | 12 |
2 files changed, 9 insertions, 5 deletions
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index 0503c917d773..483e89348f78 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -1140,7 +1140,7 @@ static inline bool skb_fclone_busy(const struct sock *sk, return skb->fclone == SKB_FCLONE_ORIG && refcount_read(&fclones->fclone_ref) > 1 && - fclones->skb2.sk == sk; + READ_ONCE(fclones->skb2.sk) == sk; } /** diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index fbf140a770d8..0dbf208a4f2f 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -2775,13 +2775,17 @@ bool tcp_schedule_loss_probe(struct sock *sk, bool advancing_rto) * a packet is still in a qdisc or driver queue. * In this case, there is very little point doing a retransmit ! */ -static bool skb_still_in_host_queue(const struct sock *sk, +static bool skb_still_in_host_queue(struct sock *sk, const struct sk_buff *skb) { if (unlikely(skb_fclone_busy(sk, skb))) { - NET_INC_STATS(sock_net(sk), - LINUX_MIB_TCPSPURIOUS_RTX_HOSTQUEUES); - return true; + set_bit(TSQ_THROTTLED, &sk->sk_tsq_flags); + smp_mb__after_atomic(); + if (skb_fclone_busy(sk, skb)) { + NET_INC_STATS(sock_net(sk), + LINUX_MIB_TCPSPURIOUS_RTX_HOSTQUEUES); + return true; + } } return false; } |