[PATCH v6 2/4] perf: add arm64 smmuv3 pmu driver

Shameerali Kolothum Thodi shameerali.kolothum.thodi at huawei.com
Mon Mar 25 02:14:35 PDT 2019



> -----Original Message-----
> From: linux-arm-kernel [mailto:linux-arm-kernel-bounces at lists.infradead.org]
> On Behalf Of Robin Murphy
> Sent: 21 March 2019 15:04
> To: Shameerali Kolothum Thodi <shameerali.kolothum.thodi at huawei.com>;
> lorenzo.pieralisi at arm.com
> Cc: mark.rutland at arm.com; vkilari at codeaurora.org;
> neil.m.leeder at gmail.com; jean-philippe.brucker at arm.com;
> pabba at codeaurora.org; John Garry <john.garry at huawei.com>;
> will.deacon at arm.com; rruigrok at codeaurora.org; Linuxarm
> <linuxarm at huawei.com>; linux-kernel at vger.kernel.org;
> linux-acpi at vger.kernel.org; Guohanjun (Hanjun Guo)
> <guohanjun at huawei.com>; andrew.murray at arm.com;
> linux-arm-kernel at lists.infradead.org
> Subject: Re: [PATCH v6 2/4] perf: add arm64 smmuv3 pmu driver

[...]

> Ah, apologies for leading you wrong on this, but it has turned out to be
> bogus - perf_pmu_register() does things for which preemption should not
> be disabled, and it flares up particularly on PREEMPT_RT. For now, I
> think the best thing to do is to bring the put_cpu() call up here (or
> just use raw_smp_processor_id() instead) and accept that those
> vanishingly-unlikely-in-practice race conditions exist until someone can
> make the registration dance more robust in the perf core itself.
> 
> Beyond that, though, I'm trusting that everything I didn't comment on
> last time and doesn't appear at a glance to have changed is still good,
> so with the comments above addressed,
> 
> Reviewed-by: Robin Murphy <robin.murphy at arm.com>
> 
> FYI, both Will and Mark are out for a while, so whilst I expect v7
> should be good to merge, don't expect any maintainer final say for at
> least a couple of weeks yet.
> 

Thanks Robin. I will address the comments and sent out v7 soon.

Cheers,
Shameer



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