tcp: fix retransmission in repair mode

Currently if a socket was repaired with a few packet in a write queue, a kernel bug may be triggered: kernel BUG at net/ipv4/tcp_output.c:2330! RIP: 0010:[<ffffffff8155784f>] tcp_retransmit_skb+0x5ff/0x610 According to the initial realization v3.4-rc2-963-gc0e88ff, all skb-s should look like already posted. This patch fixes code according with this sentence. Here are three points, which were not done in the initial patch: 1. A tcp send head should not be changed 2. Initialize TSO state of a skb 3. Reset the retransmission time This patch moves logic from tcp_sendmsg to tcp_write_xmit. A packet passes the ussual way, but isn't sent to network. This patch solves all described problems and handles tcp_sendpages. Cc: Pavel Emelyanov <[email protected]> Cc: "David S. Miller" <[email protected]> Cc: Alexey Kuznetsov <[email protected]> Cc: James Morris <[email protected]> Cc: Hideaki YOSHIFUJI <[email protected]> Cc: Patrick McHardy <[email protected]> Signed-off-by: Andrey Vagin <[email protected]> Acked-by: Pavel Emelyanov <[email protected]> Signed-off-by: David S. Miller <[email protected]>
koalo · Nov 15, 2012 · ec34232 · ec34232
1 parent 0da9a0c
commit ec34232
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Showing 2 changed files with 6 additions and 2 deletions.
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
@@ -1212,7 +1212,7 @@ int tcp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
 wait_for_sndbuf:
 			set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
 wait_for_memory:
-			if (copied && likely(!tp->repair))
+			if (copied)
 				tcp_push(sk, flags & ~MSG_MORE, mss_now, TCP_NAGLE_PUSH);
 
 			if ((err = sk_stream_wait_memory(sk, &timeo)) != 0)
@@ -1223,7 +1223,7 @@ int tcp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
 	}
 
 out:
-	if (copied && likely(!tp->repair))
+	if (copied)
 		tcp_push(sk, flags, mss_now, tp->nonagle);
 	release_sock(sk);
 	return copied + copied_syn;

diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
@@ -1986,6 +1986,9 @@ static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle,
 		tso_segs = tcp_init_tso_segs(sk, skb, mss_now);
 		BUG_ON(!tso_segs);
 
+		if (unlikely(tp->repair) && tp->repair_queue == TCP_SEND_QUEUE)
+			goto repair; /* Skip network transmission */
+
 		cwnd_quota = tcp_cwnd_test(tp, skb);
 		if (!cwnd_quota)
 			break;
@@ -2026,6 +2029,7 @@ static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle,
 		if (unlikely(tcp_transmit_skb(sk, skb, 1, gfp)))
 			break;
 
+repair:
 		/* Advance the send_head.  This one is sent out.
 		 * This call will increment packets_out.
 		 */