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    Subject[67/80] genirq: Fix race condition when stopping the irq thread
    3.0-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Ido Yariv <ido@wizery.com>

    commit 550acb19269d65f32e9ac4ddb26c2b2070e37f1c upstream.

    In irq_wait_for_interrupt(), the should_stop member is verified before
    setting the task's state to TASK_INTERRUPTIBLE and calling schedule().
    In case kthread_stop sets should_stop and wakes up the process after
    should_stop is checked by the irq thread but before the task's state
    is changed, the irq thread might never exit:

    kthread_stop irq_wait_for_interrupt
    ------------ ----------------------

    ...
    ... while (!kthread_should_stop()) {
    kthread->should_stop = 1;
    wake_up_process(k);
    wait_for_completion(&kthread->exited);
    ...
    set_current_state(TASK_INTERRUPTIBLE);

    ...

    schedule();
    }

    Fix this by checking if the thread should stop after modifying the
    task's state.

    [ tglx: Simplified it a bit ]

    Signed-off-by: Ido Yariv <ido@wizery.com>
    Link: http://lkml.kernel.org/r/1322740508-22640-1-git-send-email-ido@wizery.com
    Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
    Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

    ---
    kernel/irq/manage.c | 5 ++++-
    1 file changed, 4 insertions(+), 1 deletion(-)

    --- a/kernel/irq/manage.c
    +++ b/kernel/irq/manage.c
    @@ -620,8 +620,9 @@ static irqreturn_t irq_nested_primary_ha

    static int irq_wait_for_interrupt(struct irqaction *action)
    {
    + set_current_state(TASK_INTERRUPTIBLE);
    +
    while (!kthread_should_stop()) {
    - set_current_state(TASK_INTERRUPTIBLE);

    if (test_and_clear_bit(IRQTF_RUNTHREAD,
    &action->thread_flags)) {
    @@ -629,7 +630,9 @@ static int irq_wait_for_interrupt(struct
    return 0;
    }
    schedule();
    + set_current_state(TASK_INTERRUPTIBLE);
    }
    + __set_current_state(TASK_RUNNING);
    return -1;
    }




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