work_on_cpu: don't try to get_online_cpus() in work_on_cpu.
Impact: remove potential circular lock dependency with cpu hotplug lock This has caused more problems than it solved, with a pile of cpu hotplug locking issues. Followup patches will get_online_cpus() in callers that need it, but if they don't do it they're no worse than before when they were using set_cpus_allowed without locking. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Mike Travis <travis@sgi.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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@ -991,8 +991,8 @@ static void do_work_for_cpu(struct work_struct *w)
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* @fn: the function to run
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* @arg: the function arg
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*
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* This will return -EINVAL in the cpu is not online, or the return value
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* of @fn otherwise.
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* This will return the value @fn returns.
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* It is up to the caller to ensure that the cpu doesn't go offline.
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*/
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long work_on_cpu(unsigned int cpu, long (*fn)(void *), void *arg)
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{
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@ -1001,14 +1001,8 @@ long work_on_cpu(unsigned int cpu, long (*fn)(void *), void *arg)
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INIT_WORK(&wfc.work, do_work_for_cpu);
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wfc.fn = fn;
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wfc.arg = arg;
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get_online_cpus();
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if (unlikely(!cpu_online(cpu)))
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wfc.ret = -EINVAL;
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else {
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schedule_work_on(cpu, &wfc.work);
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flush_work(&wfc.work);
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}
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put_online_cpus();
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return wfc.ret;
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}
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