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Commit dca0aaf8 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

tcp: defer sacked assignment 



While chasing tcp_xmit_retransmit_queue() kasan issue, I found
that we could avoid reading sacked field of skb that we wont send,
possibly removing one cache line miss.

Very minor change in slow path, but why not ? ;)

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Acked-by: default avatarNeal Cardwell <ncardwell@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 53e43f39

net/ipv4/tcp_output.c

+2 −1
Original line number Diff line number Diff line
@@ -2776,7 +2776,7 @@ void tcp_xmit_retransmit_queue(struct sock *sk) 


	max_segs = tcp_tso_autosize(sk, tcp_current_mss(sk));

	tcp_for_write_queue_from(skb, sk) {

		__u8 sacked = TCP_SKB_CB(skb)->sacked;

		__u8 sacked;

		int segs;



		if (skb == tcp_send_head(sk))
@@ -2788,6 +2788,7 @@ void tcp_xmit_retransmit_queue(struct sock *sk) 
		segs = tp->snd_cwnd - tcp_packets_in_flight(tp);

		if (segs <= 0)

			return;

		sacked = TCP_SKB_CB(skb)->sacked;

		/* In case tcp_shift_skb_data() have aggregated large skbs,

		 * we need to make sure not sending too bigs TSO packets

		 */