From 5e6729ef1e7a1e3136965debb2f302c6b5570c45 Mon Sep 17 00:00:00 2001 From: Sebastian Andrzej Siewior Date: Mon, 21 Aug 2017 15:09:13 +0200 Subject: [PATCH 335/365] net: take the tcp_sk_lock lock with BH disabled Lockdep may complain about an unsafe locking scenario: | CPU0 CPU1 | ---- ---- | lock((tcp_sk_lock).lock); | lock(&per_cpu(local_softirq_locks[i], __cpu).lock); | lock((tcp_sk_lock).lock); | lock(&per_cpu(local_softirq_locks[i], __cpu).lock); in the call paths: do_current_softirqs -> tcp_v4_send_ack() vs tcp_v4_send_reset -> do_current_softirqs(). This should not happen since local_softirq_locks is per CPU. Reversing the order makes lockdep happy. Change-Id: I4b773f3dd84f8bda96067e319cfd27469f3c5dfe Reported-by: Jacek Konieczny Signed-off-by: Sebastian Andrzej Siewior --- net/ipv4/tcp_ipv4.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index 89d986d0d77d..736bd9f45c7f 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -705,8 +705,8 @@ static void tcp_v4_send_reset(const struct sock *sk, struct sk_buff *skb) arg.tos = ip_hdr(skb)->tos; arg.uid = sock_net_uid(net, sk && sk_fullsock(sk) ? sk : NULL); - local_lock(tcp_sk_lock); local_bh_disable(); + local_lock(tcp_sk_lock); 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, @@ -714,8 +714,8 @@ static void tcp_v4_send_reset(const struct sock *sk, struct sk_buff *skb) __TCP_INC_STATS(net, TCP_MIB_OUTSEGS); __TCP_INC_STATS(net, TCP_MIB_OUTRSTS); - local_bh_enable(); local_unlock(tcp_sk_lock); + local_bh_enable(); #ifdef CONFIG_TCP_MD5SIG out: @@ -793,16 +793,16 @@ static void tcp_v4_send_ack(const struct sock *sk, arg.bound_dev_if = oif; arg.tos = tos; arg.uid = sock_net_uid(net, sk_fullsock(sk) ? sk : NULL); - local_lock(tcp_sk_lock); local_bh_disable(); + local_lock(tcp_sk_lock); 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); - local_bh_enable(); local_unlock(tcp_sk_lock); + local_bh_enable(); } static void tcp_v4_timewait_ack(struct sock *sk, struct sk_buff *skb) -- 2.28.0