Re: [PATCH 2/3] percpu_stats: Simple per-cpu statistics count helper functions

From	Tejun Heo <tj@kernel.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH 2/3] percpu_stats: Simple per-cpu statistics count helper functions
Date	2016-04-07 01:00 +0200
Message-ID	<rl4Az-2wG-41@gated-at.bofh.it> (permalink)
References	<rjkgq-5Ym-3@gated-at.bofh.it> <rjkgq-5Ym-9@gated-at.bofh.it> <rkfeG-5Fz-21@gated-at.bofh.it> <rl3Et-1Ox-11@gated-at.bofh.it>
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Hello,

On Wed, Apr 06, 2016 at 05:51:45PM -0400, Waiman Long wrote:
> >>+	/*
> >>+	 * If a statistics count is in the middle of being updated, it
> >>+	 * is possible that the above clearing may not work. So we need
> >>+	 * to double check again to make sure that the counters are really
> >>+	 * cleared. Still there is a still a very small chance that the
> >>+	 * second clearing does not work.
> >>+	 */
> >>+	for_each_possible_cpu(cpu) {
> >>+		unsigned long *pstats =  per_cpu_ptr(pcs->stats, cpu);
> >>+		int stat;
> >>+
> >>+		for (stat = 0; stat<  pcs->nstats; stat++, pstats++)
> >>+			if (*pstats)
> >>+				*pstats = 0;
> >>+	}
> >I don't think this is acceptable.
> 
> I am not sure what you mean here by not acceptable. Please enlighten me on
> that.

Hmmm... I thought that was pretty clear.  Try-twice-and-we-are-probably-okay
is simply not acceptable.  Please make it watertight.

Thanks.

-- 
tejun

Thread

Re: [PATCH 2/3] percpu_stats: Simple per-cpu statistics count helper  functions Tejun Heo <tj@kernel.org> - 2016-04-04 18:10 +0200
  Re: [PATCH 2/3] percpu_stats: Simple per-cpu statistics count helper  functions Waiman Long <waiman.long@hpe.com> - 2016-04-06 22:10 +0200
  Re: [PATCH 2/3] percpu_stats: Simple per-cpu statistics count helper  functions Waiman Long <waiman.long@hpe.com> - 2016-04-07 00:00 +0200
    Re: [PATCH 2/3] percpu_stats: Simple per-cpu statistics count helper  functions Tejun Heo <tj@kernel.org> - 2016-04-07 01:00 +0200
      Re: [PATCH 2/3] percpu_stats: Simple per-cpu statistics count helper  functions Waiman Long <waiman.long@hpe.com> - 2016-04-07 18:00 +0200
        Re: [PATCH 2/3] percpu_stats: Simple per-cpu statistics count helper  functions Tejun Heo <tj@kernel.org> - 2016-04-07 18:10 +0200
          Re: [PATCH 2/3] percpu_stats: Simple per-cpu statistics count helper  functions Tejun Heo <tj@kernel.org> - 2016-04-07 21:00 +0200
            Re: [PATCH 2/3] percpu_stats: Simple per-cpu statistics count helper  functions Waiman Long <waiman.long@hpe.com> - 2016-04-07 22:40 +0200
              Re: [PATCH 2/3] percpu_stats: Simple per-cpu statistics count helper  functions Tejun Heo <tj@kernel.org> - 2016-04-07 22:50 +0200
                Re: [PATCH 2/3] percpu_stats: Simple per-cpu statistics count helper  functions Waiman Long <waiman.long@hpe.com> - 2016-04-07 23:40 +0200
          Re: [PATCH 2/3] percpu_stats: Simple per-cpu statistics count helper  functions Waiman Long <waiman.long@hpe.com> - 2016-04-07 21:10 +0200

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