Messages in this thread | | | Date | Thu, 30 Aug 2012 00:53:53 +0100 | From | Russell King - ARM Linux <> | Subject | Re: [RFC/PATCH] ARM: smp: Fix cpu_up() racing with sys_reboot |
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On Tue, Aug 21, 2012 at 09:03:49PM -0700, Stephen Boyd wrote: > Nothing stops a process from hotplugging in a CPU concurrently > with a sys_reboot() call. In such a situation we could have > ipi_cpu_stop() mark a cpu as 'offline' and _cpu_up() ignore the > fact that the CPU is not really offline and call the > CPU_UP_PREPARE notifier. When this happens stop_machine code will > complain that the cpu thread already exists and BUG_ON().
This puts us at odds with x86, which is a bad thing without first investigating whether a generic solution which fixes all arches would be more appropriate.
A better solution may be to mark those CPUs as being not-present, which will prevent them being hot-plugged back.
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