linux-kernel - Re: [PATCH V6 07/13] perf: Generic pci uncore device support

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <4FDE9B1B.8080707@intel.com>
Date:	Mon, 18 Jun 2012 11:06:03 +0800
From:	"Yan, Zheng" <zheng.z.yan@...el.com>
To:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
CC:	mingo@...e.hu, jolsa@...hat.com, eranian@...gle.com,
	andi@...stfloor.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH V6 07/13] perf: Generic pci uncore device support

On 06/16/2012 12:02 AM, Peter Zijlstra wrote:
> On Fri, 2012-06-15 at 14:31 +0800, Yan, Zheng wrote:
>> @@ -305,6 +310,22 @@ struct intel_uncore_box *uncore_alloc_box(int cpu)
>>  static struct intel_uncore_box *
>>  uncore_pmu_to_box(struct intel_uncore_pmu *pmu, int cpu)
>>  {
>> +       static struct intel_uncore_box *box;
>> +
>> +       box =  *per_cpu_ptr(pmu->box, cpu);
>> +       if (box)
>> +               return box;
>> +
>> +       raw_spin_lock(&uncore_box_lock);
>> +       list_for_each_entry(box, &pmu->box_list, list) {
>> +               if (box->phys_id == topology_physical_package_id(cpu)) {
>> +                       atomic_inc(&box->refcnt);
>> +                       *per_cpu_ptr(pmu->box, cpu) = box;
>> +                       break;
>> +               }
>> +       }
>> +       raw_spin_unlock(&uncore_box_lock);
>> +
>>         return *per_cpu_ptr(pmu->box, cpu);
>>  } 
> 
> So why can't we do that lookup from a hotplug notifier?
> 
We can. But I personally prefer not to mix pci uncore initialization
code with cpu hotplug notifier. Because pci hotplug and cpu hotplug
are separate process, I'm not completely sure which one happens first.

Regards
Yan, Zheng 

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/