tcp: do not assume TCP code is non preemptible
We want to to make TCP stack preemptible, as draining prequeue
and backlog queues can take lot of time.
Many SNMP updates were assuming that BH (and preemption) was disabled.
Need to convert some __NET_INC_STATS() calls to NET_INC_STATS()
and some __TCP_INC_STATS() to TCP_INC_STATS()
Before using this_cpu_ptr(net->ipv4.tcp_sk) in tcp_v4_send_reset()
and tcp_v4_send_ack(), we add an explicit preempt disabled section.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 87b173b..761bc49 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -692,6 +692,7 @@
offsetof(struct inet_timewait_sock, tw_bound_dev_if));
arg.tos = ip_hdr(skb)->tos;
+ preempt_disable();
ip_send_unicast_reply(*this_cpu_ptr(net->ipv4.tcp_sk),
skb, &TCP_SKB_CB(skb)->header.h4.opt,
ip_hdr(skb)->saddr, ip_hdr(skb)->daddr,
@@ -699,6 +700,7 @@
__TCP_INC_STATS(net, TCP_MIB_OUTSEGS);
__TCP_INC_STATS(net, TCP_MIB_OUTRSTS);
+ preempt_enable();
#ifdef CONFIG_TCP_MD5SIG
out:
@@ -774,12 +776,14 @@
if (oif)
arg.bound_dev_if = oif;
arg.tos = tos;
+ preempt_disable();
ip_send_unicast_reply(*this_cpu_ptr(net->ipv4.tcp_sk),
skb, &TCP_SKB_CB(skb)->header.h4.opt,
ip_hdr(skb)->saddr, ip_hdr(skb)->daddr,
&arg, arg.iov[0].iov_len);
__TCP_INC_STATS(net, TCP_MIB_OUTSEGS);
+ preempt_enable();
}
static void tcp_v4_timewait_ack(struct sock *sk, struct sk_buff *skb)
@@ -1151,12 +1155,12 @@
return false;
if (hash_expected && !hash_location) {
- __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMD5NOTFOUND);
+ NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMD5NOTFOUND);
return true;
}
if (!hash_expected && hash_location) {
- __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMD5UNEXPECTED);
+ NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMD5UNEXPECTED);
return true;
}
@@ -1342,7 +1346,7 @@
return newsk;
exit_overflow:
- __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENOVERFLOWS);
+ NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENOVERFLOWS);
exit_nonewsk:
dst_release(dst);
exit:
@@ -1432,8 +1436,8 @@
return 0;
csum_err:
- __TCP_INC_STATS(sock_net(sk), TCP_MIB_CSUMERRORS);
- __TCP_INC_STATS(sock_net(sk), TCP_MIB_INERRS);
+ TCP_INC_STATS(sock_net(sk), TCP_MIB_CSUMERRORS);
+ TCP_INC_STATS(sock_net(sk), TCP_MIB_INERRS);
goto discard;
}
EXPORT_SYMBOL(tcp_v4_do_rcv);