Messages in this thread | | | Date | Thu, 13 Oct 2022 21:50:10 +0800 | From | Chen Yu <> | Subject | Re: [PATCH] thermal: intel_powerclamp: Use first online CPU as control_cpu |
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On 2022-10-13 at 15:27:30 +0200, Rafael J. Wysocki wrote: > On Thu, Oct 13, 2022 at 3:10 PM Chen Yu <yu.c.chen@intel.com> wrote: > > > > On 2022-10-13 at 14:50:28 +0200, Rafael J. Wysocki wrote: > > > From: Rafael J. Wysocki <rafael.j.wysocki@intel.com> > > > > > > Commit 68b99e94a4a2 ("thermal: intel_powerclamp: Use get_cpu() instead > > > of smp_processor_id() to avoid crash") fixed an issue related to using > > > smp_processor_id() in preemptible context by replacing it with a pair > > > of get_cpu()/put_cpu(), but what is needed there really is any online > > > CPU and not necessarily the one currently running the code. Arguably, > > > getting the one that's running the code in there is confusing. > > > > > > For this reason, simply give the control CPU role to the first online > > > one which automatically will be CPU0 if it is online, so one check > > > can be dropped from the code for an added benefit. > > > > > > Link: https://lore.kernel.org/linux-pm/20221011113646.GA12080@duo.ucw.cz/ > > > Fixes: 68b99e94a4a2 ("thermal: intel_powerclamp: Use get_cpu() instead of smp_processor_id() to avoid crash") > > > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> > > > --- > > > drivers/thermal/intel/intel_powerclamp.c | 6 +----- > > > 1 file changed, 1 insertion(+), 5 deletions(-) > > > > > > Index: linux-pm/drivers/thermal/intel/intel_powerclamp.c > > > =================================================================== > > > --- linux-pm.orig/drivers/thermal/intel/intel_powerclamp.c > > > +++ linux-pm/drivers/thermal/intel/intel_powerclamp.c > > > @@ -516,11 +516,7 @@ static int start_power_clamp(void) > > > cpus_read_lock(); > > > > > > /* prefer BSP */ > > Above comment line is not true any more, might delete it as well? > > Well, why not? If CPU0 is the BSP, it is still preferred as before. > I see. Got it.
thanks, Chenyu > > Reviewed-by: Chen Yu <yu.c.chen@intel.com> > > Thanks! > > > > - control_cpu = 0; > > > - if (!cpu_online(control_cpu)) { > > > - control_cpu = get_cpu(); > > > - put_cpu(); > > > - } > > > + control_cpu = cpumask_first(cpu_online_mask); > > > > > > clamping = true; > > > schedule_delayed_work(&poll_pkg_cstate_work, 0); > > > > > > > > >
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