From: Eric Dumazet edumazet@google.com

stable inclusion from stable-v4.19.316 commit 4f3ae7d846b4565c0b80d65ed607c3277bc984d4 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/IAMPH5

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...

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[ Upstream commit 581073f626e387d3e7eed55c48c8495584ead7ba ]

trafgen performance considerably sank on hosts with many cores after the blamed commit.

packet_read_pending() is very expensive, and calling it in af_packet fast path defeats Daniel intent in commit b013840810c2 ("packet: use percpu mmap tx frame pending refcount")

tpacket_destruct_skb() makes room for one packet, we can immediately wakeup a producer, no need to completely drain the tx ring.

Fixes: 89ed5b519004 ("af_packet: Block execution of tasks waiting for transmit to complete in AF_PACKET") Signed-off-by: Eric Dumazet edumazet@google.com Cc: Neil Horman nhorman@tuxdriver.com Cc: Daniel Borkmann daniel@iogearbox.net Reviewed-by: Willem de Bruijn willemb@google.com Link: https://lore.kernel.org/r/20240515163358.4105915-1-edumazet@google.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org Signed-off-by: Dong Chenchen dongchenchen2@huawei.com --- net/packet/af_packet.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c index c64bcba21e47..e26ee0486ded 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -2437,8 +2437,7 @@ static void tpacket_destruct_skb(struct sk_buff *skb) ts = __packet_set_timestamp(po, ph, skb); __packet_set_status(po, ph, TP_STATUS_AVAILABLE | ts);

- if (!packet_read_pending(&po->tx_ring)) - complete(&po->skb_completion); + complete(&po->skb_completion); }

sock_wfree(skb);