[PATCH V8 16/20] mmc: block: Introduce queue semantics

Adrian Hunter
2016-11-29T10:15:35Z

Change from viewing the requests in progress as 'current' and 'previous',
to viewing them as a queue. The current request is allocated to the first
free slot. The presence of incomplete requests is determined from the
count (mq->qcnt) of entries in the queue. Non-read-write requests (i.e.
discards and flushes) are not added to the queue at all and require no
special handling. Also no special handling is needed for the
MMC_BLK_NEW_REQUEST case.

As well as allowing an arbitrarily sized queue, the queue thread function
is significantly simpler.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
---
drivers/mmc/card/block.c | 49 +++++++++++++++++++------------
drivers/mmc/card/queue.c | 76 ++++++++++++++++++++++++++++++------------------
drivers/mmc/card/queue.h | 10 +++++--
3 files changed, 85 insertions(+), 50 deletions(-)

diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c
index fdeb3f335fd5..6ead9f64cd1c 100644
--- a/drivers/mmc/card/block.c
+++ b/drivers/mmc/card/block.c
@@ -129,6 +129,13 @@ static inline int mmc_blk_part_switch(struct mmc_card *card,
struct mmc_blk_data *md);
static int get_card_status(struct mmc_card *card, u32 *status, int retries);

+static void mmc_blk_requeue(struct request_queue *q, struct request *req)
+{
+ spin_lock_irq(q->queue_lock);
+ blk_requeue_request(q, req);
+ spin_unlock_irq(q->queue_lock);
+}
+
static struct mmc_blk_data *mmc_blk_get(struct gendisk *disk)
{
struct mmc_blk_data *md;
@@ -1630,12 +1637,21 @@ static int mmc_blk_issue_rw_rq(struct mmc_queue *mq, struct request *rqc)
struct mmc_blk_request *brq;
int ret = 1, disable_multi = 0, retry = 0, type, retune_retry_done = 0;
enum mmc_blk_status status;
- struct mmc_queue_req *mqrq_cur = mq->mqrq_cur;
+ struct mmc_queue_req *mqrq_cur = NULL;
struct mmc_queue_req *mq_rq;
struct request *req;
struct mmc_async_req *areq;

- if (!rqc && !mq->mqrq_prev->req)
+ if (rqc) {
+ mqrq_cur = mmc_queue_req_find(mq, rqc);
+ if (!mqrq_cur) {
+ WARN_ON(1);
+ mmc_blk_requeue(mq->queue, rqc);
+ rqc = NULL;
+ }
+ }
+
+ if (!mq->qcnt)
return 0;

do {
@@ -1659,11 +1675,8 @@ static int mmc_blk_issue_rw_rq(struct mmc_queue *mq, struct request *rqc)
} else
areq = NULL;
areq = mmc_start_req(card->host, areq, &status);
- if (!areq) {
- if (status == MMC_BLK_NEW_REQUEST)
- mq->flags |= MMC_QUEUE_NEW_REQUEST;
+ if (!areq)
return 0;
- }

mq_rq = container_of(areq, struct mmc_queue_req, mmc_active);
brq = &mq_rq->brq;
@@ -1760,6 +1773,8 @@ static int mmc_blk_issue_rw_rq(struct mmc_queue *mq, struct request *rqc)
}
} while (ret);

+ mmc_queue_req_free(mq, mq_rq);
+
return 1;

cmd_abort:
@@ -1774,6 +1789,7 @@ static int mmc_blk_issue_rw_rq(struct mmc_queue *mq, struct request *rqc)
if (mmc_card_removed(card)) {
rqc->cmd_flags |= REQ_QUIET;
blk_end_request_all(rqc, -EIO);
+ mmc_queue_req_free(mq, mqrq_cur);
} else {
mmc_blk_rw_rq_prep(mqrq_cur, card, 0, mq);
mmc_start_req(card->host,
@@ -1781,6 +1797,8 @@ static int mmc_blk_issue_rw_rq(struct mmc_queue *mq, struct request *rqc)
}
}

+ mmc_queue_req_free(mq, mq_rq);
+
return 0;
}

@@ -1789,9 +1807,8 @@ int mmc_blk_issue_rq(struct mmc_queue *mq, struct request *req)
int ret;
struct mmc_blk_data *md = mq->blkdata;
struct mmc_card *card = md->queue.card;
- bool req_is_special = mmc_req_is_special(req);

- if (req && !mq->mqrq_prev->req)
+ if (req && !mq->qcnt)
/* claim host only for the first request */
mmc_get_card(card);

@@ -1804,20 +1821,19 @@ int mmc_blk_issue_rq(struct mmc_queue *mq, struct request *req)
goto out;
}

- mq->flags &= ~MMC_QUEUE_NEW_REQUEST;
if (req && req_op(req) == REQ_OP_DISCARD) {
/* complete ongoing async transfer before issuing discard */
- if (card->host->areq)
+ if (mq->qcnt)
mmc_blk_issue_rw_rq(mq, NULL);
ret = mmc_blk_issue_discard_rq(mq, req);
} else if (req && req_op(req) == REQ_OP_SECURE_ERASE) {
/* complete ongoing async transfer before issuing secure erase*/
- if (card->host->areq)
+ if (mq->qcnt)
mmc_blk_issue_rw_rq(mq, NULL);
ret = mmc_blk_issue_secdiscard_rq(mq, req);
} else if (req && req_op(req) == REQ_OP_FLUSH) {
/* complete ongoing async transfer before issuing flush */
- if (card->host->areq)
+ if (mq->qcnt)
mmc_blk_issue_rw_rq(mq, NULL);
ret = mmc_blk_issue_flush(mq, req);
} else {
@@ -1825,13 +1841,8 @@ int mmc_blk_issue_rq(struct mmc_queue *mq, struct request *req)
}

out:
- if ((!req && !(mq->flags & MMC_QUEUE_NEW_REQUEST)) || req_is_special)
- /*
- * Release host when there are no more requests
- * and after special request(discard, flush) is done.
- * In case sepecial request, there is no reentry to
- * the 'mmc_blk_issue_rq' with 'mqrq_prev->req'.
- */
+ /* Release host when there are no more requests */
+ if (!mq->qcnt)
mmc_put_card(card);
return ret;
}
diff --git a/drivers/mmc/card/queue.c b/drivers/mmc/card/queue.c
index 48197545b539..34e5be6b94ae 100644
--- a/drivers/mmc/card/queue.c
+++ b/drivers/mmc/card/queue.c
@@ -49,6 +49,35 @@ static int mmc_prep_request(struct request_queue *q, struct request *req)
return BLKPREP_OK;
}

+struct mmc_queue_req *mmc_queue_req_find(struct mmc_queue *mq,
+ struct request *req)
+{
+ struct mmc_queue_req *mqrq;
+ int i = ffz(mq->qslots);
+
+ if (i >= mq->qdepth)
+ return NULL;
+
+ mqrq = &mq->mqrq[i];
+ WARN_ON(mqrq->req || mq->qcnt >= mq->qdepth ||
+ test_bit(mqrq->task_id, &mq->qslots));
+ mqrq->req = req;
+ mq->qcnt += 1;
+ __set_bit(mqrq->task_id, &mq->qslots);
+
+ return mqrq;
+}
+
+void mmc_queue_req_free(struct mmc_queue *mq,
+ struct mmc_queue_req *mqrq)
+{
+ WARN_ON(!mqrq->req || mq->qcnt < 1 ||
+ !test_bit(mqrq->task_id, &mq->qslots));
+ mqrq->req = NULL;
+ mq->qcnt -= 1;
+ __clear_bit(mqrq->task_id, &mq->qslots);
+}
+
static int mmc_queue_thread(void *d)
{
struct mmc_queue *mq = d;
@@ -59,7 +88,7 @@ static int mmc_queue_thread(void *d)

down(&mq->thread_sem);
do {
- struct request *req = NULL;
+ struct request *req;

spin_lock_irq(q->queue_lock);
set_current_state(TASK_INTERRUPTIBLE);
@@ -72,38 +101,17 @@ static int mmc_queue_thread(void *d)
* Dispatch queue is empty so set flags for
* mmc_request_fn() to wake us up.
*/
- if (mq->mqrq_prev->req)
+ if (mq->qcnt)
cntx->is_waiting_last_req = true;
else
mq->asleep = true;
}
- mq->mqrq_cur->req = req;
spin_unlock_irq(q->queue_lock);

- if (req || mq->mqrq_prev->req) {
- bool req_is_special = mmc_req_is_special(req);
-
+ if (req || mq->qcnt) {
set_current_state(TASK_RUNNING);
mmc_blk_issue_rq(mq, req);
cond_resched();
- if (mq->flags & MMC_QUEUE_NEW_REQUEST) {
- mq->flags &= ~MMC_QUEUE_NEW_REQUEST;
- continue; /* fetch again */
- }
-
- /*
- * Current request becomes previous request
- * and vice versa.
- * In case of special requests, current request
- * has been finished. Do not assign it to previous
- * request.
- */
- if (req_is_special)
- mq->mqrq_cur->req = NULL;
-
- mq->mqrq_prev->brq.mrq.data = NULL;
- mq->mqrq_prev->req = NULL;
- swap(mq->mqrq_prev, mq->mqrq_cur);
} else {
if (kthread_should_stop()) {
set_current_state(TASK_RUNNING);
@@ -186,6 +194,21 @@ static void mmc_queue_setup_discard(struct request_queue *q,
queue_flag_set_unlocked(QUEUE_FLAG_SECERASE, q);
}

+static struct mmc_queue_req *mmc_queue_alloc_mqrqs(struct mmc_queue *mq,
+ int qdepth)
+{
+ struct mmc_queue_req *mqrq;
+ int i;
+
+ mqrq = kcalloc(qdepth, sizeof(*mqrq), GFP_KERNEL);
+ if (mqrq) {
+ for (i = 0; i < mq->qdepth; i++)
+ mqrq[i].task_id = i;
+ }
+
+ return mqrq;
+}
+
static bool mmc_queue_alloc_bounce_bufs(struct mmc_queue *mq,
unsigned int bouncesz)
{
@@ -286,12 +309,9 @@ int mmc_init_queue(struct mmc_queue *mq, struct mmc_card *card,
return -ENOMEM;

mq->qdepth = 2;
- mq->mqrq = kcalloc(mq->qdepth, sizeof(struct mmc_queue_req),
- GFP_KERNEL);
+ mq->mqrq = mmc_queue_alloc_mqrqs(mq, mq->qdepth);
if (!mq->mqrq)
goto blk_cleanup;
- mq->mqrq_cur = &mq->mqrq[0];
- mq->mqrq_prev = &mq->mqrq[1];
mq->queue->queuedata = mq;

blk_queue_prep_rq(mq->queue, mmc_prep_request);
diff --git a/drivers/mmc/card/queue.h b/drivers/mmc/card/queue.h
index dac8c3d010dd..95ca33098e1f 100644
--- a/drivers/mmc/card/queue.h
+++ b/drivers/mmc/card/queue.h
@@ -30,6 +30,7 @@ struct mmc_queue_req {
struct scatterlist *bounce_sg;
unsigned int bounce_sg_len;
struct mmc_async_req mmc_active;
+ int task_id;
};

struct mmc_queue {
@@ -38,14 +39,13 @@ struct mmc_queue {
struct semaphore thread_sem;
unsigned int flags;
#define MMC_QUEUE_SUSPENDED (1 << 0)
-#define MMC_QUEUE_NEW_REQUEST (1 << 1)
bool asleep;
struct mmc_blk_data *blkdata;
struct request_queue *queue;
struct mmc_queue_req *mqrq;
- struct mmc_queue_req *mqrq_cur;
- struct mmc_queue_req *mqrq_prev;
int qdepth;
+ int qcnt;
+ unsigned long qslots;
};

extern int mmc_init_queue(struct mmc_queue *, struct mmc_card *, spinlock_t *,
@@ -61,4 +61,8 @@ extern unsigned int mmc_queue_map_sg(struct mmc_queue *,

extern int mmc_access_rpmb(struct mmc_queue *);

+extern struct mmc_queue_req *mmc_queue_req_find(struct mmc_queue *,
+ struct request *);
+extern void mmc_queue_req_free(struct mmc_queue *, struct mmc_queue_req *);
+
#endif
--
1.9.1