linux-kernel - Re: [PATCH v4 2/4] block: add runtime pm helpers

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Date:	Thu, 5 Jul 2012 15:11:20 +0200
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Lin Ming <ming.m.lin@...el.com>
Cc:	Jens Axboe <axboe@...nel.dk>,
	Alan Stern <stern@...land.harvard.edu>,
	Shaohua Li <shli@...nel.org>, linux-kernel@...r.kernel.org,
	linux-pm@...r.kernel.org, linux-scsi@...r.kernel.org
Subject: Re: [PATCH v4 2/4] block: add runtime pm helpers

On Thursday, July 05, 2012, Lin Ming wrote:
> Add runtime pm helper functions:
> 
> blk_pm_runtime_init()
> blk_pre_runtime_suspend()
> blk_post_runtime_suspend()
> blk_pre_runtime_resume()
> blk_post_runtime_suspend()

What exactly do you need these things for?  Please be specific.

Thanks,
Rafael


> Signed-off-by: Lin Ming <ming.m.lin@...el.com>
> ---
> 
> v4:
> - Adds CONFIG_PM_RUNTIME check
> 
>  block/blk-core.c       |   63 ++++++++++++++++++++++++++++++++++++++++++++++++
>  include/linux/blkdev.h |   27 +++++++++++++++++++++
>  2 files changed, 90 insertions(+)
> 
> diff --git a/block/blk-core.c b/block/blk-core.c
> index 3c923a7..b94ec5f 100644
> --- a/block/blk-core.c
> +++ b/block/blk-core.c
> @@ -30,6 +30,7 @@
>  #include <linux/list_sort.h>
>  #include <linux/delay.h>
>  #include <linux/ratelimit.h>
> +#include <linux/pm_runtime.h>
>  
>  #define CREATE_TRACE_POINTS
>  #include <trace/events/block.h>
> @@ -2982,6 +2983,68 @@ void blk_finish_plug(struct blk_plug *plug)
>  }
>  EXPORT_SYMBOL(blk_finish_plug);
>  
> +#ifdef CONFIG_PM_RUNTIME
> +void blk_pm_runtime_init(struct request_queue *q, struct device *dev)
> +{
> +	q->dev = dev;
> +	q->rpm_status = RPM_ACTIVE;
> +
> +	pm_runtime_use_autosuspend(q->dev);
> +	pm_runtime_mark_last_busy(q->dev);
> +	pm_runtime_autosuspend(q->dev);
> +}
> +EXPORT_SYMBOL(blk_pm_runtime_init);
> +
> +int blk_pre_runtime_suspend(struct request_queue *q)
> +{
> +	int ret = 0;
> +
> +	spin_lock_irq(q->queue_lock);
> +	if (q->nr_pending)
> +		ret = -EBUSY;
> +	else
> +		q->rpm_status = RPM_SUSPENDING;
> +	spin_unlock_irq(q->queue_lock);
> +	return ret;
> +}
> +EXPORT_SYMBOL(blk_pre_runtime_suspend);
> +
> +void blk_post_runtime_suspend(struct request_queue *q, int err)
> +{
> +	spin_lock_irq(q->queue_lock);
> +	if (!err)
> +		q->rpm_status = RPM_SUSPENDED;
> +	else {
> +		q->rpm_status = RPM_ACTIVE;
> +		pm_runtime_mark_last_busy(q->dev);
> +	}
> +	spin_unlock_irq(q->queue_lock);
> +}
> +EXPORT_SYMBOL(blk_post_runtime_suspend);
> +
> +void blk_pre_runtime_resume(struct request_queue *q)
> +{
> +	spin_lock_irq(q->queue_lock);
> +	q->rpm_status = RPM_RESUMING;
> +	spin_unlock_irq(q->queue_lock);
> +}
> +EXPORT_SYMBOL(blk_pre_runtime_resume);
> +
> +void blk_post_runtime_resume(struct request_queue *q, int err)
> +{
> +	spin_lock_irq(q->queue_lock);
> +	if (!err) {
> +		q->rpm_status = RPM_ACTIVE;
> +		__blk_run_queue(q);
> +		pm_runtime_mark_last_busy(q->dev);
> +		pm_request_autosuspend(q->dev);
> +	} else
> +		q->rpm_status = RPM_SUSPENDED;
> +	spin_unlock_irq(q->queue_lock);
> +}
> +EXPORT_SYMBOL(blk_post_runtime_resume);
> +#endif
> +
>  int __init blk_dev_init(void)
>  {
>  	BUILD_BUG_ON(__REQ_NR_BITS > 8 *
> diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
> index ba43f40..a5b255e 100644
> --- a/include/linux/blkdev.h
> +++ b/include/linux/blkdev.h
> @@ -346,6 +346,12 @@ struct request_queue {
>  	 */
>  	struct kobject kobj;
>  
> +#ifdef CONFIG_PM_RUNTIME
> +	struct device		*dev;
> +	int			rpm_status;
> +	unsigned int		nr_pending;
> +#endif
> +
>  	/*
>  	 * queue settings
>  	 */
> @@ -893,6 +899,27 @@ struct request_queue *blk_alloc_queue_node(gfp_t, int);
>  extern void blk_put_queue(struct request_queue *);
>  
>  /*
> + * block layer runtime pm functions
> + */
> +#ifdef CONFIG_PM_RUNTIME
> +extern void blk_pm_runtime_init(struct request_queue *q, struct device *dev);
> +extern int blk_pre_runtime_suspend(struct request_queue *q);
> +extern void blk_post_runtime_suspend(struct request_queue *q, int err);
> +extern void blk_pre_runtime_resume(struct request_queue *q);
> +extern void blk_post_runtime_resume(struct request_queue *q, int err);
> +#else
> +static inline void blk_pm_runtime_init(struct request_queue *q,
> +	struct device *dev) {}
> +static inline int blk_pre_runtime_suspend(struct request_queue *q)
> +{
> +	return -ENOSYS;
> +}
> +static inline void blk_post_runtime_suspend(struct request_queue *q, int err) {}
> +static inline void blk_pre_runtime_resume(struct request_queue *q) {}
> +static inline void blk_post_runtime_resume(struct request_queue *q, int err) {}
> +#endif
> +
> +/*
>   * blk_plug permits building a queue of related requests by holding the I/O
>   * fragments for a short period. This allows merging of sequential requests
>   * into single larger request. As the requests are moved from a per-task list to
> 

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