mmc: block: Introduce queue semantics
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>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
diff --git a/drivers/mmc/core/queue.c b/drivers/mmc/core/queue.c
index 493eb10..4a20455 100644
--- a/drivers/mmc/core/queue.c
+++ b/drivers/mmc/core/queue.c
@@ -40,6 +40,35 @@ 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;
@@ -50,7 +79,7 @@ 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);
@@ -63,38 +92,17 @@ 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->new_request) {
- mq->new_request = false;
- 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);
@@ -177,6 +185,20 @@ 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(int qdepth)
+{
+ struct mmc_queue_req *mqrq;
+ int i;
+
+ mqrq = kcalloc(qdepth, sizeof(*mqrq), GFP_KERNEL);
+ if (mqrq) {
+ for (i = 0; i < qdepth; i++)
+ mqrq[i].task_id = i;
+ }
+
+ return mqrq;
+}
+
#ifdef CONFIG_MMC_BLOCK_BOUNCE
static bool mmc_queue_alloc_bounce_bufs(struct mmc_queue *mq,
unsigned int bouncesz)
@@ -279,12 +301,9 @@ 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->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);