Commit d5b38a71 authored by Eric Dumazet's avatar Eric Dumazet Committed by Jakub Kicinski
Browse files

tcp: call tcp_set_skb_tso_segs() from tcp_write_xmit() 



tcp_write_xmit() calls tcp_init_tso_segs()
to set gso_size and gso_segs on the packet.

tcp_init_tso_segs() requires the stack to maintain
an up to date tcp_skb_pcount(), and this makes sense
for packets in rtx queue. Not so much for packets
still in the write queue.

In the following patch, we don't want to deal with
tcp_skb_pcount() when moving payload from 2nd
skb to 1st skb in the write queue.

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20240418214600.1291486-3-edumazet@google.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 22555032

net/ipv4/tcp_output.c

+14 −12
Original line number Diff line number Diff line
@@ -1502,18 +1502,22 @@ static void tcp_queue_skb(struct sock *sk, struct sk_buff *skb) 
}



/* Initialize TSO segments for a packet. */

static void tcp_set_skb_tso_segs(struct sk_buff *skb, unsigned int mss_now)

static int tcp_set_skb_tso_segs(struct sk_buff *skb, unsigned int mss_now)

{

	int tso_segs;



	if (skb->len <= mss_now) {

		/* Avoid the costly divide in the normal

		 * non-TSO case.

		 */

		tcp_skb_pcount_set(skb, 1);

		TCP_SKB_CB(skb)->tcp_gso_size = 0;

	} else {

		tcp_skb_pcount_set(skb, DIV_ROUND_UP(skb->len, mss_now));

		TCP_SKB_CB(skb)->tcp_gso_size = mss_now;

		tcp_skb_pcount_set(skb, 1);

		return 1;

	}

	TCP_SKB_CB(skb)->tcp_gso_size = mss_now;

	tso_segs = DIV_ROUND_UP(skb->len, mss_now);

	tcp_skb_pcount_set(skb, tso_segs);

	return tso_segs;

}



/* Pcount in the middle of the write queue got changed, we need to do various
@@ -2097,10 +2101,9 @@ static int tcp_init_tso_segs(struct sk_buff *skb, unsigned int mss_now) 
{

	int tso_segs = tcp_skb_pcount(skb);



	if (!tso_segs || (tso_segs > 1 && tcp_skb_mss(skb) != mss_now)) {

		tcp_set_skb_tso_segs(skb, mss_now);

		tso_segs = tcp_skb_pcount(skb);

	}

	if (!tso_segs || (tso_segs > 1 && tcp_skb_mss(skb) != mss_now))

		return tcp_set_skb_tso_segs(skb, mss_now);



	return tso_segs;

}
@@ -2733,9 +2736,6 @@ static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle, 
		if (tcp_pacing_check(sk))

			break;



		tso_segs = tcp_init_tso_segs(skb, mss_now);

		BUG_ON(!tso_segs);



		cwnd_quota = tcp_cwnd_test(tp);

		if (!cwnd_quota) {

			if (push_one == 2)
@@ -2745,6 +2745,8 @@ static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle, 
				break;

		}



		tso_segs = tcp_set_skb_tso_segs(skb, mss_now);



		if (unlikely(!tcp_snd_wnd_test(tp, skb, mss_now))) {

			is_rwnd_limited = true;

			break;