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    Subject[KJ] audit return code handling for kernel_thread [8/11]
    Audit/Cleanup of kernel_thread calls, specifically checking of return codes.
    Problems seemed to fall into 3 main categories:

    1) callers of kernel_thread were inconsistent about meaning of a zero return
    code. Some callers considered a zero return code to mean success, others took
    it to mean failure. a zero return code, while not actually possible in the
    current implementation, should be considered a success (pid 0 is/should be
    valid). fixed all callers to treat zero return as success

    2) caller of kernel_thread saved return code of kernel_thread for later use
    without ever checking its value. Callers who did this tended to assume a
    non-zero return was success, and would often wait for a completion queue to be
    woken up, implying that an error (negative return code) from kernel_thread could
    lead to deadlock. Repaired by checking return code at call time, and setting
    saved return code to zero in the event of an error.

    3) callers of kernel_thread never bothered to check the return code at all.
    This can lead to seemingly unrelated errors later in execution. Fixed by
    checking return code at call time and printing a warning message on failure.

    Regards
    Neil

    Signed-off-by: Neil Horman <nhorman@tuxdriver.com>


    drivers/ieee1394/nodemgr.c | 3 ++-
    1 file changed, 2 insertions(+), 1 deletion(-)
    --- a/drivers/ieee1394/nodemgr.c
    +++ b/drivers/ieee1394/nodemgr.c
    @@ -426,7 +426,8 @@ static ssize_t fw_set_rescan(struct bus_
    * something stupid and spawn this a lot of times, but that's
    * root's fault. */
    if (state == 1)
    - kernel_thread(nodemgr_rescan_bus_thread, NULL, CLONE_KERNEL);
    + if (kernel_thread(nodemgr_rescan_bus_thread, NULL, CLONE_KERNEL) < 0)
    + printk(KERN_WARNING "Could not start 1394 bus rescan thread\n");

    return count;
    }
    -
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