From e2e8009ff72ad2a795b67785f3238af152146368 Mon Sep 17 00:00:00 2001 From: Renato Westphal Date: Mon, 19 Oct 2015 18:51:34 -0200 Subject: [PATCH] tcp: remove improper preemption check in tcp_xmit_probe_skb() Commit e520af48c7e5a introduced the following bug when setting the TCP_REPAIR sockoption: [ 2860.657036] BUG: using __this_cpu_add() in preemptible [00000000] code: daemon/12164 [ 2860.657045] caller is __this_cpu_preempt_check+0x13/0x20 [ 2860.657049] CPU: 1 PID: 12164 Comm: daemon Not tainted 4.2.3 #1 [ 2860.657051] Hardware name: Dell Inc. PowerEdge R210 II/0JP7TR, BIOS 2.0.5 03/13/2012 [ 2860.657054] ffffffff81c7f071 ffff880231e9fdf8 ffffffff8185d765 0000000000000002 [ 2860.657058] 0000000000000001 ffff880231e9fe28 ffffffff8146ed91 ffff880231e9fe18 [ 2860.657062] ffffffff81cd1a5d ffff88023534f200 ffff8800b9811000 ffff880231e9fe38 [ 2860.657065] Call Trace: [ 2860.657072] [] dump_stack+0x4f/0x7b [ 2860.657075] [] check_preemption_disabled+0xe1/0xf0 [ 2860.657078] [] __this_cpu_preempt_check+0x13/0x20 [ 2860.657082] [] tcp_xmit_probe_skb+0xc7/0x100 [ 2860.657085] [] tcp_send_window_probe+0x2d/0x30 [ 2860.657089] [] do_tcp_setsockopt.isra.29+0x74c/0x830 [ 2860.657093] [] tcp_setsockopt+0x2c/0x30 [ 2860.657097] [] sock_common_setsockopt+0x14/0x20 [ 2860.657100] [] SyS_setsockopt+0x71/0xc0 [ 2860.657104] [] entry_SYSCALL_64_fastpath+0x16/0x75 Since tcp_xmit_probe_skb() can be called from process context, use NET_INC_STATS() instead of NET_INC_STATS_BH(). Fixes: e520af48c7e5 ("tcp: add TCPWinProbe and TCPKeepAlive SNMP counters") Signed-off-by: Renato Westphal Signed-off-by: David S. Miller --- net/ipv4/tcp_output.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index 1100ffe4a722..3dbee0d83b15 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -3405,7 +3405,7 @@ static int tcp_xmit_probe_skb(struct sock *sk, int urgent, int mib) */ tcp_init_nondata_skb(skb, tp->snd_una - !urgent, TCPHDR_ACK); skb_mstamp_get(&skb->skb_mstamp); - NET_INC_STATS_BH(sock_net(sk), mib); + NET_INC_STATS(sock_net(sk), mib); return tcp_transmit_skb(sk, skb, 0, GFP_ATOMIC); } -- 2.20.1