tcp: Do not tack on TSO data to non-TSO packet (6828b92b) · Commits · 戴 / test

If a socket starts out on a non-TSO route, and then switches to a TSO route, then we will tack on data to the tail of the tx queue even if it started out life as non-TSO. This is suboptimal because all of it will then be copied and checksummed unnecessarily. This patch fixes this by ensuring that skb->ip_summed is set to CHECKSUM_PARTIAL before appending extra data beyond the MSS. Signed-off-by:

Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by:

David S. Miller <davem@davemloft.net>

net/ipv4/tcp.c

+10 −5

Original line number	Diff line number	Diff line
		@@ -903,13 +903,17 @@ int tcp_sendmsg(struct kiocb iocb, struct socket sock, struct msghdr *msg,
		iov++;

		while (seglen > 0) {
		int copy;
		int copy = 0;
		int max = size_goal;

		skb = tcp_write_queue_tail(sk);
		if (tcp_send_head(sk)) {
		if (skb->ip_summed == CHECKSUM_NONE)
		max = mss_now;
		copy = max - skb->len;
		}

		if (!tcp_send_head(sk) \|\|
		(copy = size_goal - skb->len) <= 0) {

		if (copy <= 0) {
		new_segment:
		/* Allocate new segment. If the interface is SG,
		* allocate skb fitting to single page.
		@@ -930,6 +934,7 @@ new_segment:

		skb_entail(sk, skb);
		copy = size_goal;
		max = size_goal;
		}

		/* Try to append data to the end of skb. */
		@@ -1028,7 +1033,7 @@ new_segment:
		if ((seglen -= copy) == 0 && iovlen == 0)
		goto out;

		if (skb->len < size_goal \|\| (flags & MSG_OOB))
		if (skb->len < max \|\| (flags & MSG_OOB))
		continue;

		if (forced_push(tp)) {

Admin message