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    Subject[RT PATCH 1/2 v2] kernel/cpu_chill: use schedule_hrtimeout()
    If a task calls cpu_chill() and gets woken up by a regular or spurious
    wakeup and has a signal pending, then it exits the sleep loop in
    do_nanosleep() and sets up the restart block. If restart->nanosleep.type is
    not TI_NONE then this results in accessing a stale user pointer from a
    previously interrupted syscall and a copy to user based on the stale
    pointer or a BUG() when 'type' is not supported in nanosleep_copyout().

    Instead all this trouble, use schedule_hrtimeout().

    Cc: stable-rt@vger.kernel.org
    Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
    ---
    kernel/time/hrtimer.c | 9 ++++-----
    1 file changed, 4 insertions(+), 5 deletions(-)

    diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c
    index 6c77643eaf02..c0efc22ba635 100644
    --- a/kernel/time/hrtimer.c
    +++ b/kernel/time/hrtimer.c
    @@ -1873,14 +1873,13 @@ COMPAT_SYSCALL_DEFINE2(nanosleep, struct compat_timespec __user *, rqtp,
    */
    void cpu_chill(void)
    {
    - struct timespec64 tu = {
    - .tv_nsec = NSEC_PER_MSEC,
    - };
    + ktime_t chill_time;
    unsigned int freeze_flag = current->flags & PF_NOFREEZE;

    + chill_time = ktime_set(0, NSEC_PER_MSEC);
    + set_current_state(TASK_UNINTERRUPTIBLE);
    current->flags |= PF_NOFREEZE;
    - __hrtimer_nanosleep(&tu, HRTIMER_MODE_REL_HARD, CLOCK_MONOTONIC,
    - TASK_UNINTERRUPTIBLE);
    + schedule_hrtimeout(&chill_time, HRTIMER_MODE_REL_HARD);
    if (!freeze_flag)
    current->flags &= ~PF_NOFREEZE;
    }
    --
    2.16.2
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