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>

1 files changed, 6 insertions, 6 deletions

diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 52914714b923..7bdc9c9c231b 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -649,12 +649,12 @@ static bool tcp_v6_inbound_md5_hash(const struct sock *sk,
                 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;
         }
 
@@ -825,9 +825,9 @@ static void tcp_v6_send_response(const struct sock *sk, struct sk_buff *skb, u32
         if (!IS_ERR(dst)) {
                 skb_dst_set(buff, dst);
                 ip6_xmit(ctl_sk, buff, &fl6, NULL, tclass);
-                __TCP_INC_STATS(net, TCP_MIB_OUTSEGS);
+                TCP_INC_STATS(net, TCP_MIB_OUTSEGS);
                 if (rst)
-                        __TCP_INC_STATS(net, TCP_MIB_OUTRSTS);
+                        TCP_INC_STATS(net, TCP_MIB_OUTRSTS);
                 return;
         }
 
@@ -1276,8 +1276,8 @@ discard:
         kfree_skb(skb);
         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;