linux-kernel - Re: [PATCH V5 4/9] genirq: Add runtime power management support for IRQ chips

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <7htwh2c6o9.fsf@baylibre.com>
Date:	Thu, 09 Jun 2016 15:56:54 -0700
From:	Kevin Hilman <khilman@...libre.com>
To:	Jon Hunter <jonathanh@...dia.com>
Cc:	Grygorii Strashko <grygorii.strashko@...com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Jason Cooper <jason@...edaemon.net>,
	Marc Zyngier <marc.zyngier@....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>,
	Geert Uytterhoeven <geert@...ux-m68k.org>,
	Lars-Peter Clausen <lars@...afoo.de>,
	Linus Walleij <linus.walleij@...aro.org>,
	<linux-tegra@...r.kernel.org>, <devicetree@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH V5 4/9] genirq: Add runtime power management support for IRQ chips

Jon Hunter <jonathanh@...dia.com> writes:

> On 06/06/16 15:36, Grygorii Strashko wrote:
>> On 06/06/2016 05:30 PM, Jon Hunter wrote:
>>>
>>> On 06/06/16 15:13, Grygorii Strashko wrote:
>>>> On 06/06/2016 02:53 PM, Jon Hunter wrote:
>>>>> Some IRQ chips may be located in a power domain outside of the CPU
>>>>> subsystem and hence will require device specific runtime power
>>>>> management. In order to support such IRQ chips, add a pointer for a
>>>>> device structure to the irq_chip structure, and if this pointer is
>>>>> populated by the IRQ chip driver and CONFIG_PM is selected in the kernel
>>>>> configuration, then the pm_runtime_get/put APIs for this chip will be
>>>>> called when an IRQ is requested/freed, respectively.
>>>>>
>>>>> Signed-off-by: Jon Hunter <jonathanh@...dia.com>
>>>>> Reviewed-by: Kevin Hilman <khilman@...libre.com>
>>>>> Reviewed-by: Marc Zyngier <marc.zyngier@....com>
>>>>> ---
>>>>>    include/linux/irq.h    |  4 ++++
>>>>>    kernel/irq/chip.c      | 35 +++++++++++++++++++++++++++++++++++
>>>>>    kernel/irq/internals.h |  1 +
>>>>>    kernel/irq/manage.c    | 31 ++++++++++++++++++++++++++++++-
>>>>>    4 files changed, 70 insertions(+), 1 deletion(-)
>>>>>
>>>>> diff --git a/include/linux/irq.h b/include/linux/irq.h
>>>>> index 4d758a7c604a..6c92a847394d 100644
>>>>> --- a/include/linux/irq.h
>>>>> +++ b/include/linux/irq.h
>>>>> @@ -315,6 +315,7 @@ static inline irq_hw_number_t irqd_to_hwirq(struct irq_data *d)
>>>>>    /**
>>>>>     * struct irq_chip - hardware interrupt chip descriptor
>>>>>     *
>>>>> + * @parent_device:	pointer to parent device for irqchip
>>>>>     * @name:		name for /proc/interrupts
>>>>>     * @irq_startup:	start up the interrupt (defaults to ->enable if NULL)
>>>>>     * @irq_shutdown:	shut down the interrupt (defaults to ->disable if NULL)
>>>>> @@ -354,6 +355,7 @@ static inline irq_hw_number_t irqd_to_hwirq(struct irq_data *d)
>>>>>     * @flags:		chip specific flags
>>>>>     */
>>>>>    struct irq_chip {
>>>>> +	struct device	*parent_device;
>>>>>    	const char	*name;
>>>>>    	unsigned int	(*irq_startup)(struct irq_data *data);
>>>>>    	void		(*irq_shutdown)(struct irq_data *data);
>>>>> @@ -488,6 +490,8 @@ extern void handle_bad_irq(struct irq_desc *desc);
>>>>>    extern void handle_nested_irq(unsigned int irq);
>>>>>    
>>>>>    extern int irq_chip_compose_msi_msg(struct irq_data *data, struct msi_msg *msg);
>>>>> +extern int irq_chip_pm_get(struct irq_data *data);
>>>>> +extern int irq_chip_pm_put(struct irq_data *data);
>>>>>    #ifdef	CONFIG_IRQ_DOMAIN_HIERARCHY
>>>>>    extern void irq_chip_enable_parent(struct irq_data *data);
>>>>>    extern void irq_chip_disable_parent(struct irq_data *data);
>>>>> diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c
>>>>> index 2f9f2b0e79f2..b09226e895c7 100644
>>>>> --- a/kernel/irq/chip.c
>>>>> +++ b/kernel/irq/chip.c
>>>>> @@ -1093,3 +1093,38 @@ int irq_chip_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
>>>>>    
>>>>>    	return 0;
>>>>>    }
>>>>> +
>>>>> +/**
>>>>> + * irq_chip_pm_get - Enable power for an IRQ chip
>>>>> + * @data:	Pointer to interrupt specific data
>>>>> + *
>>>>> + * Enable the power to the IRQ chip referenced by the interrupt data
>>>>> + * structure.
>>>>> + */
>>>>> +int irq_chip_pm_get(struct irq_data *data)
>>>>> +{
>>>>> +	int retval = 0;
>>>>> +
>>>>> +	if (IS_ENABLED(CONFIG_PM) && data->chip->parent_device)
>>>>> +		retval = pm_runtime_get_sync(data->chip->parent_device);
>>>>
>>>> Sry, for the late comment - above require pm_runtime_put_noidle(data->chip->parent_device);
>>>> in case of failure.
>>>
>>> No problem. Sorry, can you elaborate? I am not familiar with the
>>> _put_noidle().
>>>
>> 
>> Question here in use counter - pm_runtime_get_sync() will increment usage_count
>> always and it will not decrement it in case of failure.
>> pm_runtime_put_noidle() expected to restore usage_count state (-1).
>
> Thanks was not aware of that. 
>
> Kevin, Marc, given that you have reviewed this one, are you ok with the
> above change Grygorii is proposing? 

Yes, that's the right thing to do on error.

Kevin