linux-kernel - [PATCH v5 3/4] block: implement runtime pm strategy

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Date:	Fri,  6 Jul 2012 12:04:31 +0800
From:	Lin Ming <ming.m.lin@...el.com>
To:	Jens Axboe <axboe@...nel.dk>,
	Alan Stern <stern@...land.harvard.edu>,
	"Rafael J. Wysocki" <rjw@...k.pl>, Shaohua Li <shli@...nel.org>
Cc:	linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
	linux-scsi@...r.kernel.org
Subject: [PATCH v5 3/4] block: implement runtime pm strategy

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 resuming/suspending, then only PM request is allowed to go.
    Return NULL for other cases.

Signed-off-by: Lin Ming <ming.m.lin@...el.com>
---
 block/blk-core.c       |    7 +++++++
 block/elevator.c       |    4 ++++
 include/linux/blkdev.h |   37 +++++++++++++++++++++++++++++++++++++
 3 files changed, 48 insertions(+)

diff --git a/block/blk-core.c b/block/blk-core.c
index 1cc80ae..cb93501 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1224,6 +1224,8 @@ void __blk_put_request(struct request_queue *q, struct request *req)
 	if (unlikely(--req->ref_count))
 		return;
 
+	blk_pm_put_request(q);
+
 	elv_completed_request(q, req);
 
 	/* this is a bio leak */
@@ -2012,6 +2014,11 @@ struct request *blk_peek_request(struct request_queue *q)
 	int ret;
 
 	while ((rq = __elv_next_request(q)) != NULL) {
+
+		rq = blk_pm_peek_request(q, rq);
+		if (!rq)
+			break;
+
 		if (!(rq->cmd_flags & REQ_STARTED)) {
 			/*
 			 * This is the first time the device driver
diff --git a/block/elevator.c b/block/elevator.c
index 6a55d41..37c1a2b 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -536,6 +536,8 @@ void elv_requeue_request(struct request_queue *q, struct request *rq)
 
 	rq->cmd_flags &= ~REQ_STARTED;
 
+	blk_pm_requeue_request(q);
+
 	__elv_add_request(q, rq, ELEVATOR_INSERT_REQUEUE);
 }
 
@@ -558,6 +560,8 @@ void __elv_add_request(struct request_queue *q, struct request *rq, int where)
 {
 	trace_block_rq_insert(q, rq);
 
+	blk_pm_add_request(q, rq);
+
 	rq->q = q;
 
 	if (rq->cmd_flags & REQ_SOFTBARRIER) {
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 9395d39..c8c5951 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -908,6 +908,36 @@ 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);
+
+static inline void blk_pm_put_request(struct request_queue *q)
+{
+	if (!(--q->nr_pending) && q->dev)
+		 pm_runtime_mark_last_busy(q->dev);
+}
+
+static inline 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;
+}
+
+static inline void blk_pm_requeue_request(struct request_queue *q)
+{
+	q->nr_pending--;
+}
+
+static inline void blk_pm_add_request(struct request_queue *q,
+	struct request *rq)
+{
+	if (q->nr_pending++ == 0 && !(rq->cmd_flags & REQ_PM) &&
+		    (q->rpm_status == RPM_SUSPENDED ||
+		     q->rpm_status == RPM_SUSPENDING) && q->dev)
+		pm_request_resume(q->dev);
+}
 #else
 static inline void blk_pm_runtime_init(struct request_queue *q,
 	struct device *dev) {}
@@ -918,6 +948,13 @@ static inline int blk_pre_runtime_suspend(struct request_queue *q)
 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) {}
+
+static inline void blk_pm_put_request(struct request_queue *q) {}
+static inline struct request *blk_pm_peek_request(
+	struct request_queue *q, struct request *rq) { return rq; }
+static inline void blk_pm_requeue_request(struct request_queue *q) {}
+static inline void blk_pm_add_request(struct request_queue *q,
+	struct request *req) {}
 #endif
 
 /*
-- 
1.7.10

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