Messages in this thread | | | From | "Rafael J. Wysocki" <> | Date | Tue, 7 Sep 2021 15:41:23 +0200 | Subject | Re: [PATCH] cpufreq: intel_pstate: Fix for HWP interrupt before driver is ready |
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On Mon, Sep 6, 2021 at 9:57 PM Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com> wrote: > > On Mon, 2021-09-06 at 20:25 +0200, Rafael J. Wysocki wrote: > > On Mon, Sep 6, 2021 at 8:14 PM Srinivas Pandruvada > > <srinivas.pandruvada@linux.intel.com> wrote: > > > > > > On Mon, 2021-09-06 at 19:54 +0200, Rafael J. Wysocki wrote: > > > > > [...] > > > > > > > > We are handling offline for other thermal interrupt sources from > > > same > > > interrupt in therm-throt.c, where we do similar in offline path (by > > > TGLX). If cpufreq offline can cause such issue of changing CPU, > > > > This is not cpufreq offline, but intel_pstate_update_status() which > > may be triggered via sysfs. And again, the theoretically problematic > > thing is dereferencing cpudata (which may be cleared by a remote CPU) > > from the interrupt handler without protection. > > This will be a problem. > > > > > > I can call intel_pstate_disable_hwp_interrupt() via override from > > > https://elixir.bootlin.com/linux/latest/C/ident/thermal_throttle_offline > > > after masking APIC interrupt. > > > > But why would using RCU be harder than this? > I think, this will require all_cpu_data and cpu_data to be rcu > protected. This needs to be well tested. > > I think better to revert the patch for the next release.
Done, thanks!
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