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    SubjectRe: [PATCH] connector: Fix regression introduced by sid connector
    Sorry about that. Dont know how this escaped.  It was probably hiding between
    all the sparse warnings I get in kernel/* and a lack of knowledge in this
    Here is a new version:

    since commit 02b51df1b07b4e9ca823c89284e704cadb323cd1 (proc connector: add event
    for process becoming session leader) we have the following warning:
    Badness at kernel/softirq.c:143
    Krnl PSW : 0404c00180000000 00000000001481d4 (local_bh_enable+0xb0/0xe0)
    Call Trace:
    ([<000000013fe04100>] 0x13fe04100)
    [<000000000048a946>] sk_filter+0x9a/0xd0
    [<000000000049d938>] netlink_broadcast+0x2c0/0x53c
    [<00000000003ba9ae>] cn_netlink_send+0x272/0x2b0
    [<00000000003baef0>] proc_sid_connector+0xc4/0xd4
    [<0000000000142604>] __set_special_pids+0x58/0x90
    [<0000000000159938>] sys_setsid+0xb4/0xd8
    [<00000000001187fe>] sysc_noemu+0x10/0x16
    [<00000041616cb266>] 0x41616cb266

    The warning is
    ---> WARN_ON_ONCE(in_irq() || irqs_disabled());

    The network code must not be called with disabled interrupts but
    sys_setsid holds the tasklist_lock with spinlock_irq while calling
    the connector.
    After a discussion we agreed that we can move proc_sid_connector
    from __set_special_pids to sys_setsid.
    We also agreed that it is sufficient to change the check from
    task_session(curr) != pid into err > 0, since if we don't change the
    session, this means we were already the leader and return -EPERM.

    One last thing:
    There is also daemonize(), and some people might want to get a
    notification in that case. Since daemonize() is only needed if a user
    space does kernel_thread this does not look important (and there seems
    to be no consensus if this connector should be called in daemonize). If
    we really want this, we can add proc_sid_connector to daemonize() in an
    additional patch (Scott?)

    Signed-off-by: Christian Borntraeger <>
    CCed: Scott James Remnant <>
    CCed: Matt Helsley <>
    CCed: David S. Miller <>
    Acked-by: Oleg Nesterov <>
    Acked-by: Evgeniy Polyakov <>
    kernel/exit.c | 4 +---
    kernel/sys.c | 2 ++
    2 files changed, 3 insertions(+), 3 deletions(-)

    Index: linux-2.6/kernel/exit.c
    --- linux-2.6.orig/kernel/exit.c
    +++ linux-2.6/kernel/exit.c
    @@ -359,10 +359,8 @@ void __set_special_pids(struct pid *pid)
    struct task_struct *curr = current->group_leader;

    - if (task_session(curr) != pid) {
    + if (task_session(curr) != pid)
    change_pid(curr, PIDTYPE_SID, pid);
    - proc_sid_connector(curr);
    - }

    if (task_pgrp(curr) != pid)
    change_pid(curr, PIDTYPE_PGID, pid);
    Index: linux-2.6/kernel/sys.c
    --- linux-2.6.orig/kernel/sys.c
    +++ linux-2.6/kernel/sys.c
    @@ -1110,6 +1110,8 @@ SYSCALL_DEFINE0(setsid)
    err = session;
    + if (err > 0)
    + proc_sid_connector(group_leader);
    return err;

     \ /
      Last update: 2009-10-02 08:19    [W:0.047 / U:0.152 seconds]
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