Commit 7eec9f33 authored Jun 30, 2020 by Eric Dumazet Committed by Greg Kroah-Hartman Jul 22, 2020

tcp: fix SO_RCVLOWAT possible hangs under high mem pressure



[ Upstream commit ba3bb0e76ccd464bb66665a1941fabe55dadb3ba ]

Whenever tcp_try_rmem_schedule() returns an error, we are under
trouble and should make sure to wakeup readers so that they
can drain socket queues and eventually make room.

Fixes: 03f45c88 ("tcp: avoid extra wakeups for SO_RCVLOWAT users")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 9b7fd81c

net/ipv4/tcp_input.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -4564,6 +4564,7 @@ static void tcp_data_queue_ofo(struct sock sk, struct sk_buff skb)

		if (unlikely(tcp_try_rmem_schedule(sk, skb, skb->truesize))) {
		NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPOFODROP);
		sk->sk_data_ready(sk);
		tcp_drop(sk, skb);
		return;
		}
		@@ -4807,6 +4808,7 @@ static void tcp_data_queue(struct sock sk, struct sk_buff skb)
		sk_forced_mem_schedule(sk, skb->truesize);
		else if (tcp_try_rmem_schedule(sk, skb, skb->truesize)) {
		NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPRCVQDROP);
		sk->sk_data_ready(sk);
		goto drop;
		}