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    Subject[tip:timers/urgent] alarmtimer: Fix bug where relative alarm timers were treated as absolute
    Commit-ID:  16927776ae757d0d132bdbfabbfe2c498342bd59
    Gitweb: http://git.kernel.org/tip/16927776ae757d0d132bdbfabbfe2c498342bd59
    Author: John Stultz <john.stultz@linaro.org>
    AuthorDate: Mon, 7 Jul 2014 14:06:11 -0700
    Committer: Thomas Gleixner <tglx@linutronix.de>
    CommitDate: Tue, 8 Jul 2014 10:49:36 +0200

    alarmtimer: Fix bug where relative alarm timers were treated as absolute

    Sharvil noticed with the posix timer_settime interface, using the
    CLOCK_REALTIME_ALARM or CLOCK_BOOTTIME_ALARM clockid, if the users
    tried to specify a relative time timer, it would incorrectly be
    treated as absolute regardless of the state of the flags argument.

    This patch corrects this, properly checking the absolute/relative flag,
    as well as adds further error checking that no invalid flag bits are set.

    Reported-by: Sharvil Nanavati <sharvil@google.com>
    Signed-off-by: John Stultz <john.stultz@linaro.org>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: Ingo Molnar <mingo@kernel.org>
    Cc: Prarit Bhargava <prarit@redhat.com>
    Cc: Sharvil Nanavati <sharvil@google.com>
    Cc: stable <stable@vger.kernel.org> #3.0+
    Link: http://lkml.kernel.org/r/1404767171-6902-1-git-send-email-john.stultz@linaro.org
    Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
    ---
    kernel/time/alarmtimer.c | 20 ++++++++++++++++++--
    1 file changed, 18 insertions(+), 2 deletions(-)

    diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c
    index 88c9c65..fe75444 100644
    --- a/kernel/time/alarmtimer.c
    +++ b/kernel/time/alarmtimer.c
    @@ -585,9 +585,14 @@ static int alarm_timer_set(struct k_itimer *timr, int flags,
    struct itimerspec *new_setting,
    struct itimerspec *old_setting)
    {
    + ktime_t exp;
    +
    if (!rtcdev)
    return -ENOTSUPP;

    + if (flags & ~TIMER_ABSTIME)
    + return -EINVAL;
    +
    if (old_setting)
    alarm_timer_get(timr, old_setting);

    @@ -597,8 +602,16 @@ static int alarm_timer_set(struct k_itimer *timr, int flags,

    /* start the timer */
    timr->it.alarm.interval = timespec_to_ktime(new_setting->it_interval);
    - alarm_start(&timr->it.alarm.alarmtimer,
    - timespec_to_ktime(new_setting->it_value));
    + exp = timespec_to_ktime(new_setting->it_value);
    + /* Convert (if necessary) to absolute time */
    + if (flags != TIMER_ABSTIME) {
    + ktime_t now;
    +
    + now = alarm_bases[timr->it.alarm.alarmtimer.type].gettime();
    + exp = ktime_add(now, exp);
    + }
    +
    + alarm_start(&timr->it.alarm.alarmtimer, exp);
    return 0;
    }

    @@ -730,6 +743,9 @@ static int alarm_timer_nsleep(const clockid_t which_clock, int flags,
    if (!alarmtimer_get_rtcdev())
    return -ENOTSUPP;

    + if (flags & ~TIMER_ABSTIME)
    + return -EINVAL;
    +
    if (!capable(CAP_WAKE_ALARM))
    return -EPERM;


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