• Robert Varga's avatar
    tcp: fix CONFIG_TCP_MD5SIG + CONFIG_PREEMPT timer BUG() · 657e9649
    Robert Varga authored
    
    
    I have recently came across a preemption imbalance detected by:
    
    <4>huh, entered ffffffff80644630 with preempt_count 00000102, exited with 00000101?
    <0>------------[ cut here ]------------
    <2>kernel BUG at /usr/src/linux/kernel/timer.c:664!
    <0>invalid opcode: 0000 [1] PREEMPT SMP
    
    with ffffffff80644630 being inet_twdr_hangman().
    
    This appeared after I enabled CONFIG_TCP_MD5SIG and played with it a
    bit, so I looked at what might have caused it.
    
    One thing that struck me as strange is tcp_twsk_destructor(), as it
    calls tcp_put_md5sig_pool() -- which entails a put_cpu(), causing the
    detected imbalance. Found on 2.6.23.9, but 2.6.31 is affected as well,
    as far as I can tell.
    Signed-off-by: default avatarRobert Varga <nite@hq.alert.sk>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    657e9649