Messages in this thread | | | From | Rusty Russell <> | Subject | Re: [PATCH 4/12] arch/mips: remove references to cpu_*_map. | Date | Thu, 16 Feb 2012 10:29:24 +1030 |
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On Wed, 15 Feb 2012 14:50:02 +0530, "Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com> wrote: > > - cpu_clear(smp_processor_id(), mask); > > - for_each_cpu_mask(cpu, mask) > > - if (cpu_context(cpu, mm)) > > + for_each_online_cpu(cpu) { > > + if (cpu != smp_processor_id() && cpu_context(cpu, mm)) > > cpu_context(cpu, mm) = 0; > > + } > > > Strictly speaking, this one is not a mere cleanup. It causes a subtle change in > behaviour: earlier, it used to iterate over a local copy of cpu_online_mask, which > wouldn't change. However, with this patch, it will iterate directly over > cpu_online_mask, which can change underneath. (The preempt_disable() won't stop > new CPUs from coming in.. it only prevents CPUs from going offline, that too > provided that we use stop_machine stuff for CPU offline, which we do currently.)
There's a preempt_disable() around this whole function, so online_mask can't change.
Same with the others. > > + mask = *cpu_online_mask; > > + cpumask_clear(&mask, cpu); > > > This should be cpumask_clear_cpu(cpu, &mask);
Good catch. I copied the bitmask ops, and continually regret it.
I've rolled all these together with your fixes, added your ia64 patch, and am rebasing to -next now, so I can hand this all across to akpm.
Thanks, Rusty.
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