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From: Viresh Kumar <viresh.kumar@linaro.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>,
	Linaro Kernel Mailman List <linaro-kernel@lists.linaro.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 1/2] hrtimer: update '->active_bases' before calling hrtimer_force_reprogram()
Date: Thu, 2 Apr 2015 19:53:59 +0530	[thread overview]
Message-ID: <CAKohponHP9yhjrRt_igvA9554DwU7cUUR=VC4cLOapcgXBrZxA@mail.gmail.com> (raw)
In-Reply-To: <20150402141633.GC23123@twins.programming.kicks-ass.net>

On 2 April 2015 at 19:46, Peter Zijlstra <peterz@infradead.org> wrote:
> So then I'm not seeing how its a bug. Sure __hrtimer_get_next_event()
> will iterate all the bases again, and it will not skip the just empty
> one. But I don't see how that is anything but an inefficiency. By virtue
> of the base being empty it cannot find an event there, so its a
> pointless check.
>
> What am I missing?

Hmm. It was a bug for me because I was doing this unconditionally:
timer = container_of(timerqueue_getnext(&base->active),
+                                    struct hrtimer, node);

And this will give a container-of over NULL, as timerqueue_getnext() can
return NULL..

And so it will crash in my case.

But I understand your point, its inefficiency only :(

  reply	other threads:[~2015-04-02 14:24 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-04-02 10:51 [PATCH 0/2] hrtimer: Only iterate over active bases Viresh Kumar
2015-04-02 10:51 ` [PATCH 1/2] hrtimer: update '->active_bases' before calling hrtimer_force_reprogram() Viresh Kumar
2015-04-02 13:47   ` Peter Zijlstra
2015-04-02 13:53     ` Viresh Kumar
2015-04-02 14:16       ` Peter Zijlstra
2015-04-02 14:23         ` Viresh Kumar [this message]
2015-04-02 10:51 ` [PATCH 2/2] hrtimer: create for_each_active_base() to iterate over active clock-bases Viresh Kumar
2015-04-02 13:45   ` Peter Zijlstra
2015-04-03  5:42     ` viresh kumar

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