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From: Russell King - ARM Linux <linux@arm.linux.org.uk>
To: Daniel Thompson <daniel.thompson@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>,
	Jason Cooper <jason@lakedaemon.net>,
	linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org, patches@linaro.org,
	linaro-kernel@lists.linaro.org,
	John Stultz <john.stultz@linaro.org>,
	Sumit Semwal <sumit.semwal@linaro.org>,
	Dirk Behme <dirk.behme@de.bosch.com>,
	Daniel Drake <drake@endlessm.com>,
	Dmitry Pervushin <dpervushin@gmail.com>,
	Tim Sander <tim@krieglstein.org>,
	Stephen Boyd <sboyd@codeaurora.org>
Subject: Re: [RFC PATCH 5/5] arm: perf: Use FIQ to handle PMU events.
Date: Mon, 19 Jan 2015 17:48:18 +0000	[thread overview]
Message-ID: <20150119174818.GD26493@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <1421166931-14134-6-git-send-email-daniel.thompson@linaro.org>

On Tue, Jan 13, 2015 at 04:35:31PM +0000, Daniel Thompson wrote:
> +/*
> + * This handler is called *unconditionally* from the default NMI/FIQ
> + * handler. The irq may not be anything to do with us so the main
> + * job of this function is to figure out if the irq passed in is ours
> + * or not.
> + */
> +void cpu_pmu_handle_fiq(int irq)
> +{
> +	int cpu = smp_processor_id();

This can be either debug_smp_processor_id() or raw_smp_processor_id().
raw_smp_processor_id() is fine from FIQ contexts, as seems to be
debug_smp_processor_id(), but only because we guarantee that
irqs_disabled() in there will be true.

> +
> +	if (irq != get_cpu_var(cpu_pmu_irqs))
> +		return;

get_cpu_var() needs put_cpu_var() to undo its effects.  get_cpu_var()
calls preempt_disable(), which calls into lockdep...  I think we
determined that was fine last time we went digging?  put_cpu_var()
would call preempt_enable() which I'd hope would be safe in FIQ/NMI
contexts?

> +
> +	(void)armpmu_dispatch_irq(irq,
> +				  get_cpu_ptr(&cpu_pmu->hw_events->percpu_pmu));

Again, get_cpu_xxx() needs to be balanced with a put_cpu_xxx().


-- 
FTTC broadband for 0.8mile line: currently at 10.5Mbps down 400kbps up
according to speedtest.net.

WARNING: multiple messages have this Message-ID (diff)
From: linux@arm.linux.org.uk (Russell King - ARM Linux)
To: linux-arm-kernel@lists.infradead.org
Subject: [RFC PATCH 5/5] arm: perf: Use FIQ to handle PMU events.
Date: Mon, 19 Jan 2015 17:48:18 +0000	[thread overview]
Message-ID: <20150119174818.GD26493@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <1421166931-14134-6-git-send-email-daniel.thompson@linaro.org>

On Tue, Jan 13, 2015 at 04:35:31PM +0000, Daniel Thompson wrote:
> +/*
> + * This handler is called *unconditionally* from the default NMI/FIQ
> + * handler. The irq may not be anything to do with us so the main
> + * job of this function is to figure out if the irq passed in is ours
> + * or not.
> + */
> +void cpu_pmu_handle_fiq(int irq)
> +{
> +	int cpu = smp_processor_id();

This can be either debug_smp_processor_id() or raw_smp_processor_id().
raw_smp_processor_id() is fine from FIQ contexts, as seems to be
debug_smp_processor_id(), but only because we guarantee that
irqs_disabled() in there will be true.

> +
> +	if (irq != get_cpu_var(cpu_pmu_irqs))
> +		return;

get_cpu_var() needs put_cpu_var() to undo its effects.  get_cpu_var()
calls preempt_disable(), which calls into lockdep...  I think we
determined that was fine last time we went digging?  put_cpu_var()
would call preempt_enable() which I'd hope would be safe in FIQ/NMI
contexts?

> +
> +	(void)armpmu_dispatch_irq(irq,
> +				  get_cpu_ptr(&cpu_pmu->hw_events->percpu_pmu));

Again, get_cpu_xxx() needs to be balanced with a put_cpu_xxx().


-- 
FTTC broadband for 0.8mile line: currently at 10.5Mbps down 400kbps up
according to speedtest.net.

  parent reply	other threads:[~2015-01-19 17:48 UTC|newest]

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-01-13 16:35 [RFC PATCH 0/5] irq: Allow irqs to be routed to NMI/FIQ Daniel Thompson
2015-01-13 16:35 ` Daniel Thompson
2015-01-13 16:35 ` [RFC PATCH 1/5] arm: irq: Add a __nmi_count stat Daniel Thompson
2015-01-13 16:35   ` Daniel Thompson
2015-01-13 16:35 ` [RFC PATCH 2/5] irq: Allow interrupts to routed to NMI (or similar) Daniel Thompson
2015-01-13 16:35   ` Daniel Thompson
2015-01-19 16:21   ` Joshua Clayton
2015-01-19 16:21     ` Joshua Clayton
2015-01-19 17:33     ` Daniel Thompson
2015-01-19 17:33       ` Daniel Thompson
2015-01-13 16:35 ` [RFC PATCH 3/5] irq: gic: Add support for NMI routing Daniel Thompson
2015-01-13 16:35   ` Daniel Thompson
2015-01-13 16:35 ` [RFC PATCH 4/5] arm: perf: Make v7 support FIQ-safe Daniel Thompson
2015-01-13 16:35   ` Daniel Thompson
2015-01-13 16:35 ` [RFC PATCH 5/5] arm: perf: Use FIQ to handle PMU events Daniel Thompson
2015-01-13 16:35   ` Daniel Thompson
2015-01-19 16:35   ` Joshua Clayton
2015-01-19 16:35     ` Joshua Clayton
2015-01-20 10:18     ` Daniel Thompson
2015-01-20 10:18       ` Daniel Thompson
2015-01-20 17:35       ` Joshua Clayton
2015-01-20 17:35         ` Joshua Clayton
2015-01-19 17:48   ` Russell King - ARM Linux [this message]
2015-01-19 17:48     ` Russell King - ARM Linux
2015-01-20 10:04     ` Daniel Thompson
2015-01-20 10:04       ` Daniel Thompson
2015-01-21 17:03 ` [RFC PATCH v2 0/5] irq: Allow irqs to be routed to NMI/FIQ Daniel Thompson
2015-01-21 17:03   ` Daniel Thompson
2015-01-21 17:03   ` [RFC PATCH v2 1/5] arm: irq: Add a __nmi_count stat Daniel Thompson
2015-01-21 17:03     ` Daniel Thompson
2015-01-21 17:03   ` [RFC PATCH v2 2/5] irq: Allow interrupts to routed to NMI (or similar) Daniel Thompson
2015-01-21 17:03     ` Daniel Thompson
2015-01-24 23:37     ` Thomas Gleixner
2015-01-24 23:37       ` Thomas Gleixner
2015-01-21 17:03   ` [RFC PATCH v2 3/5] irq: gic: Add support for NMI routing Daniel Thompson
2015-01-21 17:03     ` Daniel Thompson
2015-01-21 17:03   ` [RFC PATCH v2 4/5] arm: perf: Make v7 support FIQ-safe Daniel Thompson
2015-01-21 17:03     ` Daniel Thompson
2015-01-21 17:03   ` [RFC PATCH v2 5/5] arm: perf: Use FIQ to handle PMU events Daniel Thompson
2015-01-21 17:03     ` Daniel Thompson

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