linux-kernel - Re: [PATCH v2 01/26] genirq: add irq

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Message-ID: <53FCDA8F.7070703@codeaurora.org>
Date:	Tue, 26 Aug 2014 12:05:51 -0700
From:	Stephen Boyd <sboyd@...eaurora.org>
To:	Marc Zyngier <marc.zyngier@....com>
CC:	Mark Rutland <Mark.Rutland@....com>,
	"tony@...mide.com" <tony@...mide.com>,
	Catalin Marinas <Catalin.Marinas@....com>,
	"linux@...nrisc.net" <linux@...nrisc.net>,
	Will Deacon <Will.Deacon@....com>,
	Vladimir Murzin <Vladimir.Murzin@....com>,
	"tglx@...utronix.de" <tglx@...utronix.de>,
	"jonas@...thpole.se" <jonas@...thpole.se>,
	Lorenzo Pieralisi <Lorenzo.Pieralisi@....com>,
	"linux@....linux.org.uk" <linux@....linux.org.uk>,
	"shc_work@...l.ru" <shc_work@...l.ru>,
	"shawn.guo@...escale.com" <shawn.guo@...escale.com>,
	"khilman@...aro.org" <khilman@...aro.org>,
	"jason@...edaemon.net" <jason@...edaemon.net>,
	"stefan.kristiansson@...nalahti.fi" 
	<stefan.kristiansson@...nalahti.fi>,
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	<linux-arm-kernel@...ts.infradead.org>,
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	Sudeep Holla <Sudeep.Holla@....com>,
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	"maxime.ripard@...e-electrons.com" <maxime.ripard@...e-electrons.com>,
	"vkale@....com" <vkale@....com>
Subject: Re: [PATCH v2 01/26] genirq: add irq_domain-aware core IRQ handler

On 08/26/14 11:46, Stephen Boyd wrote:
> On 08/26/14 11:07, Marc Zyngier wrote:
>> Digging into my email, one of the traces looked like this:
>>
>> stack backtrace:
>> CPU: 0 PID: 0 Comm: swapper/0 Not tainted 3.16.0-rc1+ #135
>> Call trace:
>> [<ffffffc0000882cc>] dump_backtrace+0x0/0x12c
>> [<ffffffc000088408>] show_stack+0x10/0x1c
>> [<ffffffc0004ee5f0>] dump_stack+0x74/0xc4
>> [<ffffffc0000edfbc>] lockdep_rcu_suspicious+0xe8/0x124
>> [<ffffffc00010218c>] irq_find_mapping+0x16c/0x198
>> [<ffffffc00008130c>] gic_handle_irq+0x38/0xcc
>>
>> Most drivers call irq_find_mapping outside of irq_enter()/irq_exit(), as
>> this is in handle_IRQ().
>>
> Ah ok. This is the multi-irq handler case? Has this been broken since
> v3.2 at least for the gic users? Now that we call irq_enter()/irq_exit()
> a lot more code runs, including things like updating jiffies when
> interrupts arrive and invoking softirq? Do we only call irq_exit() on
> the IPI path otherwise?
>
> Are there any plans to send this back to stable trees? Not calling
> irq_enter()/irq_exit() when we get an interrupt seems like a big problem.
>

Hmm I see we still call handle_IRQ eventually. So it's not as bad as I
first thought.

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