On Wed, 16 Jan 2013, Aaron Lu wrote:
> From: Lin Ming <ming.m.lin@xxxxxxxxx>
>
> When a request is added:
> If device is suspended or is suspending and the request is not a
> PM request, resume the device.
>
> When the last request finishes:
> Call pm_runtime_mark_last_busy().
>
> When pick a request:
> If device is resuming/suspending, then only PM request is allowed
> to go.
>
> Signed-off-by: Lin Ming <ming.m.lin@xxxxxxxxx>
> Signed-off-by: Aaron Lu <aaron.lu@xxxxxxxxx>
Just a couple of minor problems remaining...
> --- a/block/blk-core.c
> +++ b/block/blk-core.c
> @@ -2051,6 +2063,28 @@ static void blk_account_io_done(struct request *req)
> }
> }
>
> +#ifdef CONFIG_PM_RUNTIME
> +/*
> + * Don't process normal requests when queue is suspended
> + * or in the process of suspending/resuming
> + */
> +static struct request *blk_pm_peek_request(struct request_queue *q,
> + struct request *rq)
> +{
> + if (q->rpm_status == RPM_SUSPENDED ||
> + (q->rpm_status != RPM_ACTIVE && !(rq->cmd_flags & REQ_PM)))
> + return NULL;
> + else
> + return rq;
> +}
You don't check q->dev here, so the result is indefinite for devices
that don't use runtime PM. (Actually it will work out because
RPM_ACTIVE is defined as 0, but that's a pretty fragile approach.)
Either do check q->dev here, or else explicitly initialize
q->rpm_status when the queue is created.
> --- a/block/elevator.c
> +++ b/block/elevator.c
> @@ -34,6 +34,7 @@
> #include <linux/blktrace_api.h>
> #include <linux/hash.h>
> #include <linux/uaccess.h>
> +#include <linux/pm_runtime.h>
>
> #include <trace/events/block.h>
>
> @@ -515,6 +516,27 @@ void elv_bio_merged(struct request_queue *q, struct request *rq,
> e->type->ops.elevator_bio_merged_fn(q, rq, bio);
> }
>
> +#ifdef CONFIG_PM_RUNTIME
> +static void blk_pm_requeue_request(struct request *rq)
> +{
> + if (!(rq->cmd_flags & REQ_PM))
> + rq->q->nr_pending--;
> +}
You don't check q->dev here. That's okay, but it means that
q->nr_pending will be meaningless or wrong if any I/O takes place
before blk_pm_runtime_init is called.
Therefore the kerneldoc for blk_pm_runtime_init should mention that it
must not be called after any requests have been submitted. Also
mention that blk_pm_runtime_init enables runtime PM for q->dev, so the
caller shouldn't do it.
Alan Stern
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