Messages in this thread | | | Subject | Re: [PATCH] cpu/hotplug: Fix rollback during error-out in takedown_cpu() | From | Neeraj Upadhyay <> | Date | Thu, 6 Sep 2018 08:26:20 +0530 |
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On 09/05/2018 06:47 PM, Thomas Gleixner wrote: > On Wed, 5 Sep 2018, Neeraj Upadhyay wrote: >> On 09/05/2018 05:53 PM, Thomas Gleixner wrote: >>> And looking closer this is a general issue. Just that the TEARDOWN state >>> makes it simple to observe. It's universaly broken, when the first teardown >>> callback fails because, st->state is only decremented _AFTER_ the callback >>> returns success, but undo_cpu_down() increments unconditionally. >>> >> As per my understanding, there are 2 problems here; one is fixed with your >> patch, and other is cpuhp_reset_state() is used during rollback from non-AP to >> AP state, which seem to result in 2 increments of st->state (one increment >> done by cpuhp_reset_state() and another by cpu_thread_fun()) . > And how did your hack fix that up magically? I'll have a look later today. > > Thanks, > > tglx
The hack fixes it by not calling cpuhp_reset_state() and doing rollback state reset inline in _cpu_down().
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