On 04/08/2013 07:53 AM, Rik van Riel wrote:
On 04/08/2013 08:47 AM, Prarit Bhargava wrote:
When we change the system time to a low value like this, the value of
timekeeper->offs_real will be a negative value.
It seems that the WARN occurs because an hrtimer has been started in
the time
between the releasing of the timekeeper lock and the IPI call (via a
call to
on_each_cpu) in clock_was_set() in the do_settimeofday() code. The
end result
is that a REALTIME_CLOCK timer has been added with softexpires =
expires =
KTIME_MAX. The hrtimer_interrupt() fires/is called and the loop at
kernel/hrtimer.c:1289 is executed. In this loop the code subtracts the
clock base's offset (which was set to timekeeper->offs_real in
do_settimeofday()) from the current hrtimer_cpu_base->expiry value
(which
was KTIME_MAX):
KTIME_MAX - (a negative value) = overflow
A simple check for an overflow can resolve this problem. Using
KTIME_MAX
instead of the overflow value will result in the hrtimer function
being run,
and the reprogramming of the timer after that.
>
Signed-off-by: Prarit Bhargava <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: John Stultz <[email protected]>
Reviewed-by: Rik van Riel <[email protected]>
Queued in my fortglx/3.10/time branch.
thanks
-john
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
