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    Subject[PATCH 4.4 098/183] signal/cifs: Fix cifs_put_tcp_session to call send_sig instead of force_sig
    Date
    From: Eric W. Biederman <ebiederm@xmission.com>

    [ Upstream commit 72abe3bcf0911d69b46c1e8bdb5612675e0ac42c ]

    The locking in force_sig_info is not prepared to deal with a task that
    exits or execs (as sighand may change). The is not a locking problem
    in force_sig as force_sig is only built to handle synchronous
    exceptions.

    Further the function force_sig_info changes the signal state if the
    signal is ignored, or blocked or if SIGNAL_UNKILLABLE will prevent the
    delivery of the signal. The signal SIGKILL can not be ignored and can
    not be blocked and SIGNAL_UNKILLABLE won't prevent it from being
    delivered.

    So using force_sig rather than send_sig for SIGKILL is confusing
    and pointless.

    Because it won't impact the sending of the signal and and because
    using force_sig is wrong, replace force_sig with send_sig.

    Cc: Namjae Jeon <namjae.jeon@samsung.com>
    Cc: Jeff Layton <jlayton@primarydata.com>
    Cc: Steve French <smfrench@gmail.com>
    Fixes: a5c3e1c725af ("Revert "cifs: No need to send SIGKILL to demux_thread during umount"")
    Fixes: e7ddee9037e7 ("cifs: disable sharing session and tcon and add new TCP sharing code")
    Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    fs/cifs/connect.c | 2 +-
    1 file changed, 1 insertion(+), 1 deletion(-)

    diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
    index 63108343124af..b608ce741444f 100644
    --- a/fs/cifs/connect.c
    +++ b/fs/cifs/connect.c
    @@ -2246,7 +2246,7 @@ cifs_put_tcp_session(struct TCP_Server_Info *server, int from_reconnect)

    task = xchg(&server->tsk, NULL);
    if (task)
    - force_sig(SIGKILL, task);
    + send_sig(SIGKILL, task, 1);
    }

    static struct TCP_Server_Info *
    --
    2.20.1


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