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/block.c b/drivers/mmc/core/block.c
index d317e5e..16c313a 100644 (file)
--- a/drivers/mmc/core/block.c
+++ b/drivers/mmc/core/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;
@@ -1585,11 +1592,14 @@ static bool mmc_blk_rw_cmd_err(struct mmc_blk_data *md, struct mmc_card *card,
        return req_pending;
 }
 
-static void mmc_blk_rw_cmd_abort(struct mmc_card *card, struct request *req)
+static void mmc_blk_rw_cmd_abort(struct mmc_queue *mq, struct mmc_card *card,
+                                struct request *req,
+                                struct mmc_queue_req *mqrq)
 {
        if (mmc_card_removed(card))
                req->rq_flags |= RQF_QUIET;
        while (blk_end_request(req, -EIO, blk_rq_cur_bytes(req)));
+       mmc_queue_req_free(mq, mqrq);
 }
 
 /**
@@ -1609,6 +1619,7 @@ static void mmc_blk_rw_try_restart(struct mmc_queue *mq, struct request *req,
        if (mmc_card_removed(mq->card)) {
                req->rq_flags |= RQF_QUIET;
                blk_end_request_all(req, -EIO);
+               mmc_queue_req_free(mq, mqrq);
                return;
        }
        /* Else proceed and try to restart the current async request */
@@ -1623,14 +1634,23 @@ static void mmc_blk_issue_rw_rq(struct mmc_queue *mq, struct request *new_req)
        struct mmc_blk_request *brq;
        int 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 *old_req;
        struct mmc_async_req *new_areq;
        struct mmc_async_req *old_areq;
        bool req_pending = true;
 
-       if (!new_req && !mq->mqrq_prev->req)
+       if (new_req) {
+               mqrq_cur = mmc_queue_req_find(mq, new_req);
+               if (!mqrq_cur) {
+                       WARN_ON(1);
+                       mmc_blk_requeue(mq->queue, new_req);
+                       new_req = NULL;
+               }
+       }
+
+       if (!mq->qcnt)
                return;
 
        do {
@@ -1643,7 +1663,7 @@ static void mmc_blk_issue_rw_rq(struct mmc_queue *mq, struct request *new_req)
                                !IS_ALIGNED(blk_rq_sectors(new_req), 8)) {
                                pr_err("%s: Transfer size is not 4KB sector size aligned\n",
                                        new_req->rq_disk->disk_name);
-                               mmc_blk_rw_cmd_abort(card, new_req);
+                               mmc_blk_rw_cmd_abort(mq, card, new_req, mqrq_cur);
                                return;
                        }
 
@@ -1659,8 +1679,6 @@ static void mmc_blk_issue_rw_rq(struct mmc_queue *mq, struct request *new_req)
                         * and there is nothing more to do until it is
                         * complete.
                         */
-                       if (status == MMC_BLK_NEW_REQUEST)
-                               mq->new_request = true;
                        return;
                }
 
@@ -1693,7 +1711,7 @@ static void mmc_blk_issue_rw_rq(struct mmc_queue *mq, struct request *new_req)
                                pr_err("%s BUG rq_tot %d d_xfer %d\n",
                                       __func__, blk_rq_bytes(old_req),
                                       brq->data.bytes_xfered);
-                               mmc_blk_rw_cmd_abort(card, old_req);
+                               mmc_blk_rw_cmd_abort(mq, card, old_req, mq_rq);
                                return;
                        }
                        break;
@@ -1701,11 +1719,14 @@ static void mmc_blk_issue_rw_rq(struct mmc_queue *mq, struct request *new_req)
                        req_pending = mmc_blk_rw_cmd_err(md, card, brq, old_req, req_pending);
                        if (mmc_blk_reset(md, card->host, type)) {
                                if (req_pending)
-                                       mmc_blk_rw_cmd_abort(card, old_req);
+                                       mmc_blk_rw_cmd_abort(mq, card, old_req, mq_rq);
+                               else
+                                       mmc_queue_req_free(mq, mq_rq);
                                mmc_blk_rw_try_restart(mq, new_req, mqrq_cur);
                                return;
                        }
                        if (!req_pending) {
+                               mmc_queue_req_free(mq, mq_rq);
                                mmc_blk_rw_try_restart(mq, new_req, mqrq_cur);
                                return;
                        }
@@ -1718,7 +1739,7 @@ static void mmc_blk_issue_rw_rq(struct mmc_queue *mq, struct request *new_req)
                case MMC_BLK_ABORT:
                        if (!mmc_blk_reset(md, card->host, type))
                                break;
-                       mmc_blk_rw_cmd_abort(card, old_req);
+                       mmc_blk_rw_cmd_abort(mq, card, old_req, mq_rq);
                        mmc_blk_rw_try_restart(mq, new_req, mqrq_cur);
                        return;
                case MMC_BLK_DATA_ERR: {
@@ -1728,7 +1749,7 @@ static void mmc_blk_issue_rw_rq(struct mmc_queue *mq, struct request *new_req)
                        if (!err)
                                break;
                        if (err == -ENODEV) {
-                               mmc_blk_rw_cmd_abort(card, old_req);
+                               mmc_blk_rw_cmd_abort(mq, card, old_req, mq_rq);
                                mmc_blk_rw_try_restart(mq, new_req, mqrq_cur);
                                return;
                        }
@@ -1750,18 +1771,19 @@ static void mmc_blk_issue_rw_rq(struct mmc_queue *mq, struct request *new_req)
                        req_pending = blk_end_request(old_req, -EIO,
                                                      brq->data.blksz);
                        if (!req_pending) {
+                               mmc_queue_req_free(mq, mq_rq);
                                mmc_blk_rw_try_restart(mq, new_req, mqrq_cur);
                                return;
                        }
                        break;
                case MMC_BLK_NOMEDIUM:
-                       mmc_blk_rw_cmd_abort(card, old_req);
+                       mmc_blk_rw_cmd_abort(mq, card, old_req, mq_rq);
                        mmc_blk_rw_try_restart(mq, new_req, mqrq_cur);
                        return;
                default:
                        pr_err("%s: Unhandled return value (%d)",
                                        old_req->rq_disk->disk_name, status);
-                       mmc_blk_rw_cmd_abort(card, old_req);
+                       mmc_blk_rw_cmd_abort(mq, card, old_req, mq_rq);
                        mmc_blk_rw_try_restart(mq, new_req, mqrq_cur);
                        return;
                }
@@ -1778,6 +1800,8 @@ static void mmc_blk_issue_rw_rq(struct mmc_queue *mq, struct request *new_req)
                        mq_rq->brq.retune_retry_done = retune_retry_done;
                }
        } while (req_pending);
+
+       mmc_queue_req_free(mq, mq_rq);
 }
 
 void mmc_blk_issue_rq(struct mmc_queue *mq, struct request *req)
@@ -1785,9 +1809,8 @@ void 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);
 
@@ -1799,20 +1822,19 @@ void mmc_blk_issue_rq(struct mmc_queue *mq, struct request *req)
                goto out;
        }
 
-       mq->new_request = false;
        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);
                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);
                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);
                mmc_blk_issue_flush(mq, req);
        } else {
@@ -1821,13 +1843,7 @@ void mmc_blk_issue_rq(struct mmc_queue *mq, struct request *req)
        }
 
 out:
-       if ((!req && !mq->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'.
-                */
+       if (!mq->qcnt)
                mmc_put_card(card);
 }
 

diff --git a/drivers/mmc/core/queue.c b/drivers/mmc/core/queue.c
index 493eb10..4a20455 100644 (file)
--- 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);

diff --git a/drivers/mmc/core/queue.h b/drivers/mmc/core/queue.h
index e298f10..967808d 100644 (file)
--- a/drivers/mmc/core/queue.h
+++ b/drivers/mmc/core/queue.h
@@ -34,21 +34,21 @@ struct mmc_queue_req {
        struct scatterlist      *bounce_sg;
        unsigned int            bounce_sg_len;
        struct mmc_async_req    areq;
+       int                     task_id;
 };
 
 struct mmc_queue {
        struct mmc_card         *card;
        struct task_struct      *thread;
        struct semaphore        thread_sem;
-       bool                    new_request;
        bool                    suspended;
        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 *,
@@ -64,4 +64,8 @@ extern void mmc_queue_bounce_post(struct mmc_queue_req *);
 
 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