Re: [PATCH v1 2/3] PM / Sleep: introduce dpm_for_each_dev

From: "Rafael J. Wysocki" <rjw@sisk.pl>
To: Ming Lei <ming.lei@canonical.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
	"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
	Borislav Petkov <borislav.petkov@amd.com>,
	linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org
Subject: Re: [PATCH v1 2/3] PM / Sleep: introduce dpm_for_each_dev
Date: Sat, 18 Aug 2012 00:02:26 +0200	[thread overview]
Message-ID: <201208180002.26563.rjw@sisk.pl> (raw)
In-Reply-To: <1345212420-1707-3-git-send-email-ming.lei@canonical.com>

On Friday, August 17, 2012, Ming Lei wrote:
> dpm_list and its pm lock provide a good way to iterate all
> devices in system. Except this way, there is no other easy
> way to iterate devices in system.
> 
> firmware loader need to cache firmware images for devices
> before system sleep, so introduce the function to meet its
> demand.
> 
> Reported-by: Fengguang Wu <fengguang.wu@intel.com>
> Signed-off-by: Ming Lei <ming.lei@canonical.com>

Well.

> ---
>  drivers/base/power/main.c |   22 ++++++++++++++++++++++
>  include/linux/pm.h        |    5 +++++
>  2 files changed, 27 insertions(+)
> 
> diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c
> index 57f5814..23b417f 100644
> --- a/drivers/base/power/main.c
> +++ b/drivers/base/power/main.c
> @@ -1349,3 +1349,25 @@ int device_pm_wait_for_dev(struct device *subordinate, struct device *dev)
>  	return async_error;
>  }
>  EXPORT_SYMBOL_GPL(device_pm_wait_for_dev);
> +
> +/**
> + * dpm_for_each_dev - device iterator.
> + * @data: data for the callback.
> + * @fn: function to be called for each device.
> + *
> + * Iterate over devices in dpm_list, and call @fn for each device,
> + * passing it @data.
> + */
> +void dpm_for_each_dev(void *data, void (*fn)(struct device *, void *))

Is this function actually used more than once?

> +{
> +	struct device *dev;
> +
> +	if (!fn)
> +		return;
> +
> +	device_pm_lock();
> +	list_for_each_entry(dev, &dpm_list, power.entry)
> +		fn(dev, data);
> +	device_pm_unlock();
> +}
> +EXPORT_SYMBOL_GPL(dpm_for_each_dev);
> diff --git a/include/linux/pm.h b/include/linux/pm.h
> index 44d1f23..007e687 100644
> --- a/include/linux/pm.h
> +++ b/include/linux/pm.h
> @@ -640,6 +640,7 @@ extern void __suspend_report_result(const char *function, void *fn, int ret);
>  	} while (0)
>  
>  extern int device_pm_wait_for_dev(struct device *sub, struct device *dev);
> +extern void dpm_for_each_dev(void *data, void (*fn)(struct device *, void *));
>  
>  extern int pm_generic_prepare(struct device *dev);
>  extern int pm_generic_suspend_late(struct device *dev);
> @@ -679,6 +680,10 @@ static inline int device_pm_wait_for_dev(struct device *a, struct device *b)
>  	return 0;
>  }
>  
> +static inline void dpm_for_each_dev(void *data, void (*fn)(struct device *, void *))
> +{
> +}
> +
>  #define pm_generic_prepare	NULL
>  #define pm_generic_suspend	NULL
>  #define pm_generic_resume	NULL

Rafael