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Message-ID: <87si5t3mcu.fsf@ashishki-desk.ger.corp.intel.com> Date: Fri, 02 Oct 2015 07:50:25 +0300 From: Alexander Shishkin <alexander.shishkin@...ux.intel.com> To: Mathieu Poirier <mathieu.poirier@...aro.org> Cc: Greg KH <gregkh@...uxfoundation.org>, a.p.zijlstra@...llo.nl, Arnaldo Carvalho de Melo <acme@...nel.org>, Ingo Molnar <mingo@...hat.com>, Jon Corbet <corbet@....net>, Adrian Hunter <adrian.hunter@...el.com>, Chunyan Zhang <zhang.chunyan@...aro.org>, Mike Leach <mike.leach@....com>, Tor Jeremiassen <tor@...com>, Al Grant <al.grant@....com>, Paweł Moll <pawel.moll@....com>, "linux-arm-kernel\@lists.infradead.org" <linux-arm-kernel@...ts.infradead.org>, linux-doc@...r.kernel.org, "linux-kernel\@vger.kernel.org" <linux-kernel@...r.kernel.org> Subject: Re: [RFC PATCH 15/20] coresight: etm-perf: implementing 'setup_aux()' API Mathieu Poirier <mathieu.poirier@...aro.org> writes: > On 30 September 2015 at 05:50, Alexander Shishkin > <alexander.shishkin@...ux.intel.com> wrote: >> Mathieu Poirier <mathieu.poirier@...aro.org> writes: >> >>> +static void *etm_setup_aux(int cpu, void **pages, >>> + int nr_pages, bool overwrite) >>> +{ >>> + struct coresight_device *csdev; >>> + >>> + if (cpu == -1) >>> + cpu = smp_processor_id(); >>> + >>> + csdev = per_cpu(csdev_sink, cpu); >>> + if (!csdev) >>> + return NULL; >>> + >>> + return sink_ops(csdev)->setup_aux(csdev, cpu, pages, >>> + nr_pages, overwrite); >> >> Is it guaranteed that this sink would always have .setup_aux()? > > A setup_aux() is vital to the design, both on Intel and ARM. I really > don't see how one could go without it. I can return NULL if it hasn't > been provided - that way the setup will fail without triggering a core > dump. It wasn't clear to me that the sink that ends up in csdev_sink will always be the one that does have .setup_aux(). And if it indeed doesn't, it's better to refuse to setup a buffer than crash. Regards, -- Alex -- 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/
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