Messages in this thread | | | Date | Thu, 25 Jun 2015 21:18:02 +0200 | From | Peter Zijlstra <> | Subject | Re: [RFC][PATCH 12/13] stop_machine: Remove lglock |
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On Tue, Jun 23, 2015 at 07:24:16PM +0200, Oleg Nesterov wrote: > IOW. Suppose we add ->work_mutex into struct cpu_stopper. Btw, > I think we should move all per-cpu variables there... > > Now, > > lock_stop_cpus_works(cpumask) > { > for_each_cpu(cpu, cpumask) > mutex_lock(per_cpu(cpu_stopper_task, cpu).work_mutex); > } > > unlock_stop_cpus_works(cpumask) > { > for_each_cpu(cpu, cpumask) > mutex_lock(...); > } > > which should be used instead of stop_cpus_mutex. After this change > stop_two_cpus() can just use stop_cpus().
Right, lockdep annotating that will be 'interesting' though. And stop_two_cpus() then has the problem of allocating a cpumask. Simpler to let it keep 'abuse' the queueing spinlock in there.
> Off-topic. Can't we make __stop_machine() static? The only caller, > _cpu_down() can safely call stop_machine(), get_online_cpus() is > fine under cpu_hotplug_begin().
Can do I think.
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