mmc: core: Introduce host claiming by context

Currently the host can be claimed by a task.  Change this so that the host
can be claimed by a context that may or may not be a task.  This provides
for the host to be claimed by a block driver queue to support blk-mq, while
maintaining compatibility with the existing use of mmc_claim_host().

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

1 files changed, 41 insertions, 7 deletions

diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index 66c9cf49ad2f..b997cf92ce6c 100644
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -832,9 +832,36 @@ unsigned int mmc_align_data_size(struct mmc_card *card, unsigned int sz)
 }
 EXPORT_SYMBOL(mmc_align_data_size);
 
+/*
+ * Allow claiming an already claimed host if the context is the same or there is
+ * no context but the task is the same.
+ */
+static inline bool mmc_ctx_matches(struct mmc_host *host, struct mmc_ctx *ctx,
+				   struct task_struct *task)
+{
+	return host->claimer == ctx ||
+	       (!ctx && task && host->claimer->task == task);
+}
+
+static inline void mmc_ctx_set_claimer(struct mmc_host *host,
+				       struct mmc_ctx *ctx,
+				       struct task_struct *task)
+{
+	if (!host->claimer) {
+		if (ctx)
+			host->claimer = ctx;
+		else
+			host->claimer = &host->default_ctx;
+	}
+	if (task)
+		host->claimer->task = task;
+}
+
 /**
  *	__mmc_claim_host - exclusively claim a host
  *	@host: mmc host to claim
+ *	@ctx: context that claims the host or NULL in which case the default
+ *	context will be used
  *	@abort: whether or not the operation should be aborted
  *
  *	Claim a host for a set of operations.  If @abort is non null and
@@ -842,8 +869,10 @@ EXPORT_SYMBOL(mmc_align_data_size);
  *	that non-zero value without acquiring the lock.  Returns zero
  *	with the lock held otherwise.
  */
-int __mmc_claim_host(struct mmc_host *host, atomic_t *abort)
+int __mmc_claim_host(struct mmc_host *host, struct mmc_ctx *ctx,
+		     atomic_t *abort)
 {
+	struct task_struct *task = ctx ? NULL : current;
 	DECLARE_WAITQUEUE(wait, current);
 	unsigned long flags;
 	int stop;
@@ -856,7 +885,7 @@ int __mmc_claim_host(struct mmc_host *host, atomic_t *abort)
 	while (1) {
 		set_current_state(TASK_UNINTERRUPTIBLE);
 		stop = abort ? atomic_read(abort) : 0;
-		if (stop || !host->claimed || host->claimer == current)
+		if (stop || !host->claimed || mmc_ctx_matches(host, ctx, task))
 			break;
 		spin_unlock_irqrestore(&host->lock, flags);
 		schedule();
@@ -865,7 +894,7 @@ int __mmc_claim_host(struct mmc_host *host, atomic_t *abort)
 	set_current_state(TASK_RUNNING);
 	if (!stop) {
 		host->claimed = 1;
-		host->claimer = current;
+		mmc_ctx_set_claimer(host, ctx, task);
 		host->claim_cnt += 1;
 		if (host->claim_cnt == 1)
 			pm = true;
@@ -900,6 +929,7 @@ void mmc_release_host(struct mmc_host *host)
 		spin_unlock_irqrestore(&host->lock, flags);
 	} else {
 		host->claimed = 0;
+		host->claimer->task = NULL;
 		host->claimer = NULL;
 		spin_unlock_irqrestore(&host->lock, flags);
 		wake_up(&host->wq);
@@ -913,10 +943,10 @@ EXPORT_SYMBOL(mmc_release_host);
  * This is a helper function, which fetches a runtime pm reference for the
  * card device and also claims the host.
  */
-void mmc_get_card(struct mmc_card *card)
+void mmc_get_card(struct mmc_card *card, struct mmc_ctx *ctx)
 {
 	pm_runtime_get_sync(&card->dev);
-	mmc_claim_host(card->host);
+	__mmc_claim_host(card->host, ctx, NULL);
 }
 EXPORT_SYMBOL(mmc_get_card);
 
@@ -924,9 +954,13 @@ EXPORT_SYMBOL(mmc_get_card);
  * This is a helper function, which releases the host and drops the runtime
  * pm reference for the card device.
  */
-void mmc_put_card(struct mmc_card *card)
+void mmc_put_card(struct mmc_card *card, struct mmc_ctx *ctx)
 {
-	mmc_release_host(card->host);
+	struct mmc_host *host = card->host;
+
+	WARN_ON(ctx && host->claimer != ctx);
+
+	mmc_release_host(host);
 	pm_runtime_mark_last_busy(&card->dev);
 	pm_runtime_put_autosuspend(&card->dev);
 }