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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