mmc: core: Allocate per-request data using the block layer core

The mmc_queue_req is a per-request state container the MMC core uses
to carry bounce buffers, pointers to asynchronous requests and so on.
Currently allocated as a static array of objects, then as a request
comes in, a mmc_queue_req is assigned to it, and used during the
lifetime of the request.

This is backwards compared to how other block layer drivers work:
they usally let the block core provide a per-request struct that get
allocated right beind the struct request, and which can be obtained
using the blk_mq_rq_to_pdu() helper. (The _mq_ infix in this function
name is misleading: it is used by both the old and the MQ block
layer.)

The per-request struct gets allocated to the size stored in the queue
variable .cmd_size initialized using the .init_rq_fn() and
cleaned up using .exit_rq_fn().

The block layer code makes the MMC core rely on this mechanism to
allocate the per-request mmc_queue_req state container.

Doing this make a lot of complicated queue handling go away. We only
need to keep the .qnct that keeps count of how many request are
currently being processed by the MMC layer. The MQ block layer will
replace also this once we transition to it.

Doing this refactoring is necessary to move the ioctl() operations
into custom block layer requests tagged with REQ_OP_DRV_[IN|OUT]
instead of the custom code using the BigMMCHostLock that we have
today: those require that per-request data be obtainable easily from
a request after creating a custom request with e.g.:

struct request *rq = blk_get_request(q, REQ_OP_DRV_IN, __GFP_RECLAIM);
struct mmc_queue_req *mq_rq = req_to_mq_rq(rq);

And this is not possible with the current construction, as the request
is not immediately assigned the per-request state container, but
instead it gets assigned when the request finally enters the MMC
queue, which is way too late for custom requests.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
[Ulf: Folded in the fix to drop a call to blk_cleanup_queue()]
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Tested-by: Heiner Kallweit <hkallweit1@gmail.com>

1 files changed, 57 insertions, 163 deletions

diff --git a/drivers/mmc/core/queue.c b/drivers/mmc/core/queue.c
index 70ba7f94c706..d6c7b4cde4db 100644
--- a/drivers/mmc/core/queue.c
+++ b/drivers/mmc/core/queue.c
@@ -40,35 +40,6 @@ 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;
@@ -149,11 +120,11 @@ static void mmc_request_fn(struct request_queue *q)
 		wake_up_process(mq->thread);
 }
 
-static struct scatterlist *mmc_alloc_sg(int sg_len)
+static struct scatterlist *mmc_alloc_sg(int sg_len, gfp_t gfp)
 {
 	struct scatterlist *sg;
 
-	sg = kmalloc_array(sg_len, sizeof(*sg), GFP_KERNEL);
+	sg = kmalloc_array(sg_len, sizeof(*sg), gfp);
 	if (sg)
 		sg_init_table(sg, sg_len);
 
@@ -179,80 +150,6 @@ static void mmc_queue_setup_discard(struct request_queue *q,
 		queue_flag_set_unlocked(QUEUE_FLAG_SECERASE, q);
 }
 
-static void mmc_queue_req_free_bufs(struct mmc_queue_req *mqrq)
-{
-	kfree(mqrq->bounce_sg);
-	mqrq->bounce_sg = NULL;
-
-	kfree(mqrq->sg);
-	mqrq->sg = NULL;
-
-	kfree(mqrq->bounce_buf);
-	mqrq->bounce_buf = NULL;
-}
-
-static void mmc_queue_reqs_free_bufs(struct mmc_queue_req *mqrq, int qdepth)
-{
-	int i;
-
-	for (i = 0; i < qdepth; i++)
-		mmc_queue_req_free_bufs(&mqrq[i]);
-}
-
-static void mmc_queue_free_mqrqs(struct mmc_queue_req *mqrq, int qdepth)
-{
-	mmc_queue_reqs_free_bufs(mqrq, qdepth);
-	kfree(mqrq);
-}
-
-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;
-}
-
-static int mmc_queue_alloc_bounce_bufs(struct mmc_queue_req *mqrq, int qdepth,
-				       unsigned int bouncesz)
-{
-	int i;
-
-	for (i = 0; i < qdepth; i++) {
-		mqrq[i].bounce_buf = kmalloc(bouncesz, GFP_KERNEL);
-		if (!mqrq[i].bounce_buf)
-			return -ENOMEM;
-
-		mqrq[i].sg = mmc_alloc_sg(1);
-		if (!mqrq[i].sg)
-			return -ENOMEM;
-
-		mqrq[i].bounce_sg = mmc_alloc_sg(bouncesz / 512);
-		if (!mqrq[i].bounce_sg)
-			return -ENOMEM;
-	}
-
-	return 0;
-}
-
-static bool mmc_queue_alloc_bounce(struct mmc_queue_req *mqrq, int qdepth,
-				   unsigned int bouncesz)
-{
-	int ret;
-
-	ret = mmc_queue_alloc_bounce_bufs(mqrq, qdepth, bouncesz);
-	if (ret)
-		mmc_queue_reqs_free_bufs(mqrq, qdepth);
-
-	return !ret;
-}
-
 static unsigned int mmc_queue_calc_bouncesz(struct mmc_host *host)
 {
 	unsigned int bouncesz = MMC_QUEUE_BOUNCESZ;
@@ -273,71 +170,61 @@ static unsigned int mmc_queue_calc_bouncesz(struct mmc_host *host)
 	return bouncesz;
 }
 
-static int mmc_queue_alloc_sgs(struct mmc_queue_req *mqrq, int qdepth,
-			       int max_segs)
+/**
+ * mmc_init_request() - initialize the MMC-specific per-request data
+ * @q: the request queue
+ * @req: the request
+ * @gfp: memory allocation policy
+ */
+static int mmc_init_request(struct request_queue *q, struct request *req,
+			    gfp_t gfp)
 {
-	int i;
+	struct mmc_queue_req *mq_rq = req_to_mmc_queue_req(req);
+	struct mmc_queue *mq = q->queuedata;
+	struct mmc_card *card = mq->card;
+	struct mmc_host *host = card->host;
 
-	for (i = 0; i < qdepth; i++) {
-		mqrq[i].sg = mmc_alloc_sg(max_segs);
-		if (!mqrq[i].sg)
+	mq_rq->req = req;
+
+	if (card->bouncesz) {
+		mq_rq->bounce_buf = kmalloc(card->bouncesz, gfp);
+		if (!mq_rq->bounce_buf)
+			return -ENOMEM;
+		if (card->bouncesz > 512) {
+			mq_rq->sg = mmc_alloc_sg(1, gfp);
+			if (!mq_rq->sg)
+				return -ENOMEM;
+			mq_rq->bounce_sg = mmc_alloc_sg(card->bouncesz / 512,
+							gfp);
+			if (!mq_rq->bounce_sg)
+				return -ENOMEM;
+		}
+	} else {
+		mq_rq->bounce_buf = NULL;
+		mq_rq->bounce_sg = NULL;
+		mq_rq->sg = mmc_alloc_sg(host->max_segs, gfp);
+		if (!mq_rq->sg)
 			return -ENOMEM;
 	}
 
 	return 0;
 }
 
-void mmc_queue_free_shared_queue(struct mmc_card *card)
-{
-	if (card->mqrq) {
-		mmc_queue_free_mqrqs(card->mqrq, card->qdepth);
-		card->mqrq = NULL;
-	}
-}
-
-static int __mmc_queue_alloc_shared_queue(struct mmc_card *card, int qdepth)
+static void mmc_exit_request(struct request_queue *q, struct request *req)
 {
-	struct mmc_host *host = card->host;
-	struct mmc_queue_req *mqrq;
-	unsigned int bouncesz;
-	int ret = 0;
-
-	if (card->mqrq)
-		return -EINVAL;
+	struct mmc_queue_req *mq_rq = req_to_mmc_queue_req(req);
 
-	mqrq = mmc_queue_alloc_mqrqs(qdepth);
-	if (!mqrq)
-		return -ENOMEM;
-
-	card->mqrq = mqrq;
-	card->qdepth = qdepth;
+	/* It is OK to kfree(NULL) so this will be smooth */
+	kfree(mq_rq->bounce_sg);
+	mq_rq->bounce_sg = NULL;
 
-	bouncesz = mmc_queue_calc_bouncesz(host);
+	kfree(mq_rq->bounce_buf);
+	mq_rq->bounce_buf = NULL;
 
-	if (bouncesz && !mmc_queue_alloc_bounce(mqrq, qdepth, bouncesz)) {
-		bouncesz = 0;
-		pr_warn("%s: unable to allocate bounce buffers\n",
-			mmc_card_name(card));
-	}
+	kfree(mq_rq->sg);
+	mq_rq->sg = NULL;
 
-	card->bouncesz = bouncesz;
-
-	if (!bouncesz) {
-		ret = mmc_queue_alloc_sgs(mqrq, qdepth, host->max_segs);
-		if (ret)
-			goto out_err;
-	}
-
-	return ret;
-
-out_err:
-	mmc_queue_free_shared_queue(card);
-	return ret;
-}
-
-int mmc_queue_alloc_shared_queue(struct mmc_card *card)
-{
-	return __mmc_queue_alloc_shared_queue(card, 2);
+	mq_rq->req = NULL;
 }
 
 /**
@@ -360,13 +247,21 @@ int mmc_init_queue(struct mmc_queue *mq, struct mmc_card *card,
 		limit = (u64)dma_max_pfn(mmc_dev(host)) << PAGE_SHIFT;
 
 	mq->card = card;
-	mq->queue = blk_init_queue(mmc_request_fn, lock);
+	mq->queue = blk_alloc_queue(GFP_KERNEL);
 	if (!mq->queue)
 		return -ENOMEM;
-
-	mq->mqrq = card->mqrq;
-	mq->qdepth = card->qdepth;
+	mq->queue->queue_lock = lock;
+	mq->queue->request_fn = mmc_request_fn;
+	mq->queue->init_rq_fn = mmc_init_request;
+	mq->queue->exit_rq_fn = mmc_exit_request;
+	mq->queue->cmd_size = sizeof(struct mmc_queue_req);
 	mq->queue->queuedata = mq;
+	mq->qcnt = 0;
+	ret = blk_init_allocated_queue(mq->queue);
+	if (ret) {
+		blk_cleanup_queue(mq->queue);
+		return ret;
+	}
 
 	blk_queue_prep_rq(mq->queue, mmc_prep_request);
 	queue_flag_set_unlocked(QUEUE_FLAG_NONROT, mq->queue);
@@ -374,6 +269,7 @@ int mmc_init_queue(struct mmc_queue *mq, struct mmc_card *card,
 	if (mmc_can_erase(card))
 		mmc_queue_setup_discard(mq->queue, card);
 
+	card->bouncesz = mmc_queue_calc_bouncesz(host);
 	if (card->bouncesz) {
 		blk_queue_bounce_limit(mq->queue, BLK_BOUNCE_ANY);
 		blk_queue_max_hw_sectors(mq->queue, card->bouncesz / 512);
@@ -400,7 +296,6 @@ int mmc_init_queue(struct mmc_queue *mq, struct mmc_card *card,
 	return 0;
 
 cleanup_queue:
-	mq->mqrq = NULL;
 	blk_cleanup_queue(mq->queue);
 	return ret;
 }
@@ -422,7 +317,6 @@ void mmc_cleanup_queue(struct mmc_queue *mq)
 	blk_start_queue(q);
 	spin_unlock_irqrestore(q->queue_lock, flags);
 
-	mq->mqrq = NULL;
 	mq->card = NULL;
 }
 EXPORT_SYMBOL(mmc_cleanup_queue);