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From: Mark Rutland <mark.rutland@arm.com>
To: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: fu.wei@linaro.org, rjw@rjwysocki.net, lenb@kernel.org,
	daniel.lezcano@linaro.org, tglx@linutronix.de,
	marc.zyngier@arm.com, sudeep.holla@arm.com,
	hanjun.guo@linaro.org, linux-arm-kernel@lists.infradead.org,
	linaro-acpi@lists.linaro.org, linux-kernel@vger.kernel.org,
	linux-acpi@vger.kernel.org, rruigrok@codeaurora.org,
	harba@codeaurora.org, cov@codeaurora.org, timur@codeaurora.org,
	graeme.gregory@linaro.org, al.stone@linaro.org, jcm@redhat.com,
	wei@redhat.com, arnd@arndb.de, catalin.marinas@arm.com,
	will.deacon@arm.com, Suravee.Suthikulpanit@amd.com,
	leo.duran@amd.com, wim@iguana.be, linux@roeck-us.net,
	linux-watchdog@vger.kernel.org, tn@semihalf.com,
	christoffer.dall@linaro.org, julien.grall@arm.com
Subject: Re: [PATCH v24 09/11] acpi/arm64: Add memory-mapped timer support in GTDT driver
Date: Wed, 19 Apr 2017 16:07:25 +0100	[thread overview]
Message-ID: <20170419150725.GH27829@leverpostej> (raw)
In-Reply-To: <20170418172107.GA1401@red-moon>

On Tue, Apr 18, 2017 at 06:21:07PM +0100, Lorenzo Pieralisi wrote:
> On Sat, Apr 15, 2017 at 02:40:12AM +0800, fu.wei@linaro.org wrote:

> > +error:
> > +	for (i = 0; i < ARCH_TIMER_MEM_MAX_FRAMES; i++) {
> > +		frame = &timer_mem->frame[i];
> > +		if (frame->phys_irq > 0)
> > +			acpi_unregister_irq(frame->phys_irq);
> > +		if (frame->virt_irq > 0)
> > +			acpi_unregister_irq(frame->virt_irq);
> > +	}
> 
> There are three error paths, none of them reset [i,gtdt_frame],
> correct ?

Correct.

> If yes, why can't it simply be written like this ?
> 
> for (; i >= 0; i--, gtdt_frame--) {
> 	frame = &timer_mem->frame[gtdt_frame->frame_number];
> 
> 	/* not sure this check is actually needed */
> 	if (gtdt_frame->common_flags & ACPI_GTDT_GT_IS_SECURE_TIMER)
> 		continue;
> 
> 	if (frame->phys_irq > 0)
> 		acpi_unregister_gsi(gtdt_frame->timer_interrupt);
> 	if (frame->virt_irq > 0)
> 		acpi_unregister_gsi(gtdt_frame->virtual_timer_interrupt);
> }

A reverse loop of this form will work.

That requires some restructuring, and care to avoid going out of bounds
instantaneously with the gtdt_frame--, so as to not invoke nasal demons.

I've attacked this locally, and will send this out after testing. I'll
drop the new ACPI API patch.

Thanks,
Mark.

WARNING: multiple messages have this Message-ID (diff)
From: mark.rutland@arm.com (Mark Rutland)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v24 09/11] acpi/arm64: Add memory-mapped timer support in GTDT driver
Date: Wed, 19 Apr 2017 16:07:25 +0100	[thread overview]
Message-ID: <20170419150725.GH27829@leverpostej> (raw)
In-Reply-To: <20170418172107.GA1401@red-moon>

On Tue, Apr 18, 2017 at 06:21:07PM +0100, Lorenzo Pieralisi wrote:
> On Sat, Apr 15, 2017 at 02:40:12AM +0800, fu.wei at linaro.org wrote:

> > +error:
> > +	for (i = 0; i < ARCH_TIMER_MEM_MAX_FRAMES; i++) {
> > +		frame = &timer_mem->frame[i];
> > +		if (frame->phys_irq > 0)
> > +			acpi_unregister_irq(frame->phys_irq);
> > +		if (frame->virt_irq > 0)
> > +			acpi_unregister_irq(frame->virt_irq);
> > +	}
> 
> There are three error paths, none of them reset [i,gtdt_frame],
> correct ?

Correct.

> If yes, why can't it simply be written like this ?
> 
> for (; i >= 0; i--, gtdt_frame--) {
> 	frame = &timer_mem->frame[gtdt_frame->frame_number];
> 
> 	/* not sure this check is actually needed */
> 	if (gtdt_frame->common_flags & ACPI_GTDT_GT_IS_SECURE_TIMER)
> 		continue;
> 
> 	if (frame->phys_irq > 0)
> 		acpi_unregister_gsi(gtdt_frame->timer_interrupt);
> 	if (frame->virt_irq > 0)
> 		acpi_unregister_gsi(gtdt_frame->virtual_timer_interrupt);
> }

A reverse loop of this form will work.

That requires some restructuring, and care to avoid going out of bounds
instantaneously with the gtdt_frame--, so as to not invoke nasal demons.

I've attacked this locally, and will send this out after testing. I'll
drop the new ACPI API patch.

Thanks,
Mark.

  reply	other threads:[~2017-04-19 15:07 UTC|newest]

Thread overview: 41+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-04-14 18:40 [PATCH v24 00/11] acpi, clocksource: add GTDT driver and GTDT support in arm_arch_timer fu.wei
2017-04-14 18:40 ` fu.wei at linaro.org
2017-04-14 18:40 ` [PATCH v24 01/11] clocksource: arm_arch_timer: split dt-only rate handling fu.wei
2017-04-14 18:40   ` fu.wei at linaro.org
2017-04-14 18:40 ` [PATCH v24 02/11] clocksource: arm_arch_timer: refactor arch_timer_needs_probing fu.wei
2017-04-14 18:40   ` fu.wei at linaro.org
2017-04-14 18:40 ` [PATCH v24 03/11] clocksource: arm_arch_timer: move arch_timer_needs_of_probing into DT init call fu.wei
2017-04-14 18:40   ` fu.wei at linaro.org
2017-04-14 18:40 ` [PATCH v24 04/11] clocksource: arm_arch_timer: add structs to describe MMIO timer fu.wei
2017-04-14 18:40   ` fu.wei at linaro.org
     [not found] ` <20170414184014.8524-1-fu.wei-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
2017-04-14 18:40   ` [PATCH v24 05/11] clocksource: arm_arch_timer: split MMIO timer probing fu.wei-QSEj5FYQhm4dnm+yROfE0A
2017-04-14 18:40     ` fu.wei at linaro.org
2017-04-14 18:40     ` fu.wei
2017-04-14 18:40   ` [PATCH v24 06/11] acpi/arm64: Add GTDT table parse driver fu.wei-QSEj5FYQhm4dnm+yROfE0A
2017-04-14 18:40     ` fu.wei at linaro.org
2017-04-14 18:40     ` fu.wei
2017-04-14 18:40 ` [PATCH v24 07/11] clocksource: arm_arch_timer: simplify ACPI support code fu.wei
2017-04-14 18:40   ` fu.wei at linaro.org
2017-04-14 18:40 ` [PATCH v24 08/11] acpi: Introduce acpi_unregister_irq function fu.wei
2017-04-14 18:40   ` fu.wei at linaro.org
2017-04-18 15:58   ` Mark Rutland
2017-04-18 15:58     ` Mark Rutland
2017-04-19 15:09     ` Mark Rutland
2017-04-19 15:09       ` Mark Rutland
2017-04-14 18:40 ` [PATCH v24 09/11] acpi/arm64: Add memory-mapped timer support in GTDT driver fu.wei
2017-04-14 18:40   ` fu.wei at linaro.org
2017-04-18 17:21   ` Lorenzo Pieralisi
2017-04-18 17:21     ` Lorenzo Pieralisi
2017-04-19 15:07     ` Mark Rutland [this message]
2017-04-19 15:07       ` Mark Rutland
2017-04-19 15:45       ` Mark Rutland
2017-04-19 15:45         ` Mark Rutland
2017-04-19 15:45         ` Mark Rutland
2017-04-19 15:56         ` Lorenzo Pieralisi
2017-04-19 15:56           ` Lorenzo Pieralisi
2017-04-19 15:56           ` Lorenzo Pieralisi
2017-04-14 18:40 ` [PATCH v24 10/11] clocksource: arm_arch_timer: add GTDT support for memory-mapped timer fu.wei
2017-04-14 18:40   ` fu.wei at linaro.org
2017-04-14 18:40 ` [PATCH v24 11/11] acpi/arm64: Add SBSA Generic Watchdog support in GTDT driver fu.wei
2017-04-14 18:40   ` fu.wei at linaro.org
2017-04-14 18:40   ` fu.wei

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