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SubjectRe: [PATCH] posix-timers: CLOCK_MONOTONIC_RAW: fix the usage of ->it_clock
On Sat, 20 Dec 2008, Oleg Nesterov wrote:

> (compile tested)
>
> common_timer_create() and common_timer_set() blindly pass ->it_clock to
> hrtimer_init() as clock_id. This used to work until CLOCK_MONOTONIC_RAW
> was introduced, now we should be careful.
>
> Perhaps it makes sense to add BUG_ON(clock_id >= HRTIMER_MAX_CLOCK_BASES)
> to __hrtimer_init(), the wrong clock_id leads to catastrophe.
>
> Reported-by: Eric Sesterhenn <snakebyte@gmx.de>
> Signed-off-by: Oleg Nesterov <oleg@redhat.com>
>
> --- K-28/kernel/posix-timers.c~CLOCK_MONOTONIC_RAW 2008-12-02 17:12:40.000000000 +0100
> +++ K-28/kernel/posix-timers.c 2008-12-20 18:23:28.000000000 +0100
> @@ -191,12 +191,20 @@ static inline int common_clock_set(const
> return do_sys_settimeofday(tp, NULL);
> }
>
> -static int common_timer_create(struct k_itimer *new_timer)
> +static inline int
> +__common_timer_init(struct k_itimer *timer, enum hrtimer_mode mode)
> {
> - hrtimer_init(&new_timer->it.real.timer, new_timer->it_clock, 0);
> + clockid_t clock_id = timer->it_clock ?
> + CLOCK_MONOTONIC : CLOCK_REALTIME;
> + hrtimer_init(&timer->it.real.timer, clock_id, mode);
> return 0;
> }

No, this is wrong. We do not want to create a timer for
CLOCK_MONOTONIC_RAW.

tglx


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