[PATCH V4 25/30] mmc: queue: Share mmc request array between partitions

[Adrian Hunter <adrian.hunter@intel.com>]

eMMC can have multiple internal partitions that are represented as separate
disks / queues. However the card has only 1 command queue which must be
empty when switching partitions. Consequently the array of mmc requests
that are queued can be shared between partitions saving memory.

Keep a pointer to the mmc request queue on the card, and use that instead
of allocating a new one for each partition. Use a reference count to keep
track of when to free it.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
---
 drivers/mmc/card/queue.c | 43 +++++++++++++++++++++++++++++++++++++------
 include/linux/mmc/card.h |  4 ++++
 2 files changed, 41 insertions(+), 6 deletions(-)

diff --git a/drivers/mmc/card/queue.c b/drivers/mmc/card/queue.c
index 3315a565bdaf..5457591cc739 100644
--- a/drivers/mmc/card/queue.c
+++ b/drivers/mmc/card/queue.c
@@ -198,10 +198,17 @@ static struct mmc_queue_req *mmc_queue_alloc_mqrqs(struct mmc_queue *mq,
 	struct mmc_queue_req *mqrq;
 	int i;
 
+	if (mq->card->mqrq) {
+		mq->card->mqrq_ref_cnt += 1;
+		return mq->card->mqrq;
+	}
+
 	mqrq = kcalloc(qdepth, sizeof(*mqrq), GFP_KERNEL);
 	if (mqrq) {
 		for (i = 0; i < mq->qdepth; i++)
 			mqrq[i].task_id = i;
+		mq->card->mqrq = mqrq;
+		mq->card->mqrq_ref_cnt = 1;
 	}
 
 	return mqrq;
@@ -212,6 +219,9 @@ static bool mmc_queue_alloc_bounce_bufs(struct mmc_queue *mq,
 {
 	int i;
 
+	if (mq->card->mqrq_ref_cnt > 1)
+		return !!mq->mqrq[0].bounce_buf;
+
 	for (i = 0; i < mq->qdepth; i++) {
 		mq->mqrq[i].bounce_buf = kmalloc(bouncesz, GFP_KERNEL);
 		if (!mq->mqrq[i].bounce_buf)
@@ -235,6 +245,9 @@ static int mmc_queue_alloc_bounce_sgs(struct mmc_queue *mq,
 {
 	int i, ret;
 
+	if (mq->card->mqrq_ref_cnt > 1)
+		return 0;
+
 	for (i = 0; i < mq->qdepth; i++) {
 		mq->mqrq[i].sg = mmc_alloc_sg(1, &ret);
 		if (ret)
@@ -252,6 +265,9 @@ static int mmc_queue_alloc_sgs(struct mmc_queue *mq, int max_segs)
 {
 	int i, ret;
 
+	if (mq->card->mqrq_ref_cnt > 1)
+		return 0;
+
 	for (i = 0; i < mq->qdepth; i++) {
 		mq->mqrq[i].sg = mmc_alloc_sg(max_segs, &ret);
 		if (ret)
@@ -281,6 +297,19 @@ static void mmc_queue_reqs_free_bufs(struct mmc_queue *mq)
 		mmc_queue_req_free_bufs(&mq->mqrq[i]);
 }
 
+static void mmc_queue_free_mqrqs(struct mmc_queue *mq)
+{
+	if (!mq->mqrq)
+		return;
+
+	if (!--mq->card->mqrq_ref_cnt) {
+		mmc_queue_reqs_free_bufs(mq);
+		kfree(mq->card->mqrq);
+		mq->card->mqrq = NULL;
+	}
+	mq->mqrq = NULL;
+}
+
 /**
  * mmc_init_queue - initialise a queue structure.
  * @mq: mmc queue
@@ -371,9 +400,7 @@ int mmc_init_queue(struct mmc_queue *mq, struct mmc_card *card,
 	return 0;
 
  cleanup_queue:
-	mmc_queue_reqs_free_bufs(mq);
-	kfree(mq->mqrq);
-	mq->mqrq = NULL;
+	mmc_queue_free_mqrqs(mq);
 blk_cleanup:
 	blk_cleanup_queue(mq->queue);
 	return ret;
@@ -396,9 +423,7 @@ void mmc_cleanup_queue(struct mmc_queue *mq)
 	blk_start_queue(q);
 	spin_unlock_irqrestore(q->queue_lock, flags);
 
-	mmc_queue_reqs_free_bufs(mq);
-	kfree(mq->mqrq);
-	mq->mqrq = NULL;
+	mmc_queue_free_mqrqs(mq);
 
 	mq->card = NULL;
 }
@@ -414,6 +439,9 @@ int mmc_packed_init(struct mmc_queue *mq, struct mmc_card *card)
 	if (mq->qdepth != 2)
 		return -EINVAL;
 
+	if (mqrq_cur->packed)
+		goto out;
+
 	mqrq_cur->packed = kzalloc(sizeof(struct mmc_packed), GFP_KERNEL);
 	if (!mqrq_cur->packed) {
 		pr_warn("%s: unable to allocate packed cmd for mqrq_cur\n",
@@ -444,6 +472,9 @@ void mmc_packed_clean(struct mmc_queue *mq)
 	struct mmc_queue_req *mqrq_cur = &mq->mqrq[0];
 	struct mmc_queue_req *mqrq_prev = &mq->mqrq[1];
 
+	if (mq->card->mqrq_ref_cnt > 1)
+		return;
+
 	kfree(mqrq_cur->packed);
 	mqrq_cur->packed = NULL;
 	kfree(mqrq_prev->packed);
diff --git a/include/linux/mmc/card.h b/include/linux/mmc/card.h
index 3d7434e48566..0acf6e0a8e83 100644
--- a/include/linux/mmc/card.h
+++ b/include/linux/mmc/card.h
@@ -207,6 +207,7 @@ struct mmc_host;
 struct mmc_ios;
 struct sdio_func;
 struct sdio_func_tuple;
+struct mmc_queue_req;
 
 #define SDIO_MAX_FUNCS		7
 
@@ -319,6 +320,9 @@ struct mmc_card {
 	struct dentry		*debugfs_root;
 	struct mmc_part	part[MMC_NUM_PHY_PARTITION]; /* physical partitions */
 	unsigned int    nr_parts;
+
+	struct mmc_queue_req	*mqrq;		/* Shared queue structure */
+	int			mqrq_ref_cnt;	/* Shared queue ref. count */
 };
 
 /*
-- 
1.9.1