linux-kernel - Re: [PATCH 06/15] irqdomain: Ensure type settings match for an existing mapping

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Message-ID: <56EBD976.7090107@nvidia.com>
Date:	Fri, 18 Mar 2016 10:33:26 +0000
From:	Jon Hunter <jonathanh@...dia.com>
To:	Grygorii Strashko <grygorii.strashko@...com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Jason Cooper <jason@...edaemon.net>,
	Marc Zyngier <marc.zyngier@....com>,
	Benoît Cousson <bcousson@...libre.com>,
	Tony Lindgren <tony@...mide.com>,
	Rob Herring <robh+dt@...nel.org>,
	Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	"Kumar Gala" <galak@...eaurora.org>,
	Stephen Warren <swarren@...dotorg.org>,
	"Thierry Reding" <thierry.reding@...il.com>
CC:	Kevin Hilman <khilman@...nel.org>,
	Geert Uytterhoeven <geert@...ux-m68k.org>,
	Lars-Peter Clausen <lars@...afoo.de>,
	Linus Walleij <linus.walleij@...aro.org>,
	<linux-tegra@...r.kernel.org>, <linux-omap@...r.kernel.org>,
	<devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 06/15] irqdomain: Ensure type settings match for an
 existing mapping


On 18/03/16 10:03, Grygorii Strashko wrote:
> On 03/17/2016 08:18 PM, Jon Hunter wrote:
>>
>> On 17/03/16 14:19, Jon Hunter wrote:
>>> When mapping an IRQ, if a mapping already exists, then we simply return
>>> the virtual IRQ number. However, we do not check that the type settings
>>> for the existing mapping match those for the mapping that is about to be
>>> created. It may be unlikely that the type settings would not match, but
>>> check for this and don't return a valid IRQ mapping if the type settings
>>> do not match.
>>>
>>> WARN if the type return by irq_domain_translate() has bits outside the
>>> sense mask set and then clear these bits. If these bits are not cleared
>>> then this will cause the comparision of the type settings for an
>>> existing mapping to fail with that of the new mapping even if the sense
>>> bit themselves match. The reason being is that the existing type
>>> settings are read by calling irq_get_trigger_type() which will clear
>>> any bits outside the sense mask. This will allow us to detect irqchips
>>> that are not correctly clearing these bits and fix them.
>>>
>>> Signed-off-by: Jon Hunter <jonathanh@...dia.com>
>>> ---
>>>   kernel/irq/irqdomain.c | 59
>>> ++++++++++++++++++++++++++++++++++++--------------
>>>   1 file changed, 43 insertions(+), 16 deletions(-)
>>>
>>> diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c
>>> index 3a519a01118b..0ea285baa619 100644
>>> --- a/kernel/irq/irqdomain.c
>>> +++ b/kernel/irq/irqdomain.c
>>> @@ -549,6 +549,13 @@ static int irq_domain_translate(struct
>>> irq_domain *d,
>>>                        fwspec->param, fwspec->param_count,
>>>                        hwirq, type);
>>>
> 
> 
>>> +    /*
>>> +     * WARN if the irqchip returns a type with bits
>>> +     * outside the sense mask set and clear these bits.
>>> +     */
>>> +    if (WARN_ON(*type & ~IRQ_TYPE_SENSE_MASK))
>>> +        *type &= IRQ_TYPE_SENSE_MASK;
> 
> Not sure that this warn and in this place make sense.
> type will come unchanged here from caller irq_create_fwspec_mapping()

Yes you are right. I missed the return statement. I can move to
irq_create_fwspec_mapping().

Cheers
Jon