• Renato Westphal's avatar
    tcp: remove improper preemption check in tcp_xmit_probe_skb() · e2e8009f
    Renato Westphal authored
    Commit e520af48 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]  [<ffffffff8185d765>] dump_stack+0x4f/0x7b
    [ 2860.657075]  [<ffffffff8146ed91>] check_preemption_disabled+0xe1/0xf0
    [ 2860.657078]  [<ffffffff8146edd3>] __this_cpu_preempt_check+0x13/0x20
    [ 2860.657082]  [<ffffffff817e0bc7>] tcp_xmit_probe_skb+0xc7/0x100
    [ 2860.657085]  [<ffffffff817e1e2d>] tcp_send_window_probe+0x2d/0x30
    [ 2860.657089]  [<ffffffff817d1d8c>] do_tcp_setsockopt.isra.29+0x74c/0x830
    [ 2860.657093]  [<ffffffff817d1e9c>] tcp_setsockopt+0x2c/0x30
    [ 2860.657097]  [<ffffffff81767b74>] sock_common_setsockopt+0x14/0x20
    [ 2860.657100]  [<ffffffff817669e1>] SyS_setsockopt+0x71/0xc0
    [ 2860.657104]  [<ffffffff81865172>] 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: e520af48 ("tcp: add TCPWinProbe and TCPKeepAlive SNMP counters")
    Signed-off-by: default avatarRenato Westphal <renatow@taghos.com.br>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    e2e8009f
tcp_output.c 101 KB