From: Peter Zijlstra <peterz@infradead.org>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>, Rik van Riel <riel@redhat.com>,
Tejun Heo <tj@kernel.org>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 6/6] stop_machine: kill stop_cpus_lock and lg_double_lock/unlock()
Date: Sun, 2 Aug 2015 00:36:09 +0200 [thread overview]
Message-ID: <20150801223609.GD25159@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <20150801105718.GA13901@redhat.com>
On Sat, Aug 01, 2015 at 12:57:18PM +0200, Oleg Nesterov wrote:
> > > + if (stop_work_pending(stopper1) != stop_work_pending(stopper2))
> > > + goto unlock;
> >
> > You could DoS/false positive this by running stop_one_cpu() in a loop,
> > and thereby 'always' having work pending on one but not the other.
>
> IIRC no. I am pretty sure stop_one_cpu() doesn't use stopper->stop_work,
> only stop_machine() does.
Urgh, I missed you were testing the cpu_stopper::stop_work not the
cpu_stopper::works list.
next prev parent reply other threads:[~2015-08-01 22:36 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-21 19:22 [PATCH v2 0/6] stop_machine: cleanups, fix, remove lglock Oleg Nesterov
2015-07-21 19:22 ` [PATCH v2 1/6] stop_machine: move cpu_stopper_task and stop_cpus_work into struct cpu_stopper Oleg Nesterov
2015-07-21 19:22 ` [PATCH v2 2/6] stop_machine: don't do for_each_cpu() twice in queue_stop_cpus_work() Oleg Nesterov
2015-07-21 19:22 ` [PATCH v2 3/6] stop_machine: unexport __stop_machine() Oleg Nesterov
2015-07-21 19:22 ` [PATCH v2 4/6] stop_machine: use cpu_stop_fn_t where possible Oleg Nesterov
2015-07-21 19:22 ` [PATCH v2 5/6] stop_machine: cpu_stop_park() should remove cpu_stop_work's from list Oleg Nesterov
2015-07-21 19:22 ` [PATCH v2 6/6] stop_machine: kill stop_cpus_lock and lg_double_lock/unlock() Oleg Nesterov
2015-07-30 21:55 ` Peter Zijlstra
2015-07-31 11:12 ` Peter Zijlstra
2015-07-31 14:17 ` Peter Zijlstra
2015-08-03 14:58 ` Oleg Nesterov
2015-08-01 10:57 ` Oleg Nesterov
2015-08-01 22:36 ` Peter Zijlstra [this message]
2015-08-03 14:58 ` Oleg Nesterov
2015-07-30 17:34 ` [PATCH v2 0/6] stop_machine: cleanups, fix, remove lglock Peter Zijlstra
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