On Tue, 22 May 2012, Lin Ming wrote:
> When a request is added:
> If device is suspended or is suspending and the request is not a
> PM request, resume the device.
>
> When a request finishes:
> Call pm_runtime_mark_last_busy().
>
> When pick a request:
> If device is not active, then only PM request is allowed to go.
> Return NULL for other request.
You've got the right idea. There are a few things that need fixing, in
this patch and in 4/4.
> --- a/block/blk-core.c
> +++ b/block/blk-core.c
> @@ -1130,6 +1130,10 @@ void __blk_put_request(struct request_queue *q, struct request *req)
> if (unlikely(--req->ref_count))
> return;
>
> + /* PM request is not accounted */
> + if (!(req->cmd_flags & REQ_PM) && !(--q->nr_pending) && q->dev)
I don't see that it makes any difference. You might as well count PM
requests along with the others, here and elsewhere.
> + pm_runtime_mark_last_busy(q->dev);
> +
> elv_completed_request(q, req);
>
> /* this is a bio leak */
> @@ -1918,6 +1922,12 @@ struct request *blk_peek_request(struct request_queue *q)
> int ret;
>
> while ((rq = __elv_next_request(q)) != NULL) {
> + /* Only PM request is allowed to go if the queue is suspended */
> + if (q->rpm_status != RPM_ACTIVE && !(rq->cmd_flags & REQ_PM)) {
> + rq = NULL;
> + break;
> + }
Not even PM requests should be allowed to go if the status is
RPM_SUSPENDED.
Is this the only interface by which a client driver can get a request
from the queue?
Alan Stern
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