Re: [RFC,PATCH 1/2] cputimers/proc: do_task_stat()->task_times()can race with getrusage()

[Stanislaw Gruszka]

On Fri, Mar 26, 2010 at 08:37:23AM +0100, Stanislaw Gruszka wrote:
> On Fri, Mar 26, 2010 at 09:23:44AM +0530, Balbir Singh wrote:
> > * Oleg Nesterov <oleg@xxxxxxxxxx> [2010-03-24 21:45:50]:
> > 
> > > do_task_stat()->task_times() can race with getrusage(), they both can
> > > try to update task->prev_Xtime at the same time.
> > > 
> > > Remove this bit of d180c5bc "sched: Introduce task_times() to replace
> > > task_{u,s}time()".
> > 
> > One of the reasons for adding this accuracy was to avoid sampling
> > based noise and errors that occur with utime and stime.
> > 
> > As long as there is no preemption during the assignment, I think we
> > should be OK. 
> > 
> > I see two options
> > 
> > 1. Disable preemption around assignment
> That one sounds very good.
No. Preemption will not help here.

Stanislaw
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/