On Mon, Oct 16, 2023 at 11:50:34AM -0700, srinivas pandruvada wrote: I'll respond to the rest tomorrow, it's far too late. > > > Also, same question as to the amd folks; what serializes those > > > static > > > variables? > > > > That's a good one. > > This function which is checking static variables is called from cpufreq > ->init callback. Which in turn is called from a function which is > passed as startup() function pointer to > cpuhp_setup_state_nocalls_cpuslocked(). > > I see that startup() callbacks are called under a mutex > cpuhp_state_mutex for each present CPUs. So if some tear down happen, > that is also protected by the same mutex. The assumption is here is > that cpuhp_invoke_callback() in hotplug state machine is not called in > parallel on two CPUs by the hotplug state machine. But I see activity > on parallel bringup, so this is questionable now. Parallel bringup should still serialise this. It mostly only does the hardware bringup in parallel. Having a pointer back to the cpu hotplug lock would make it easier to untangle this code though.
