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Subject[PATCH V8 01/14] mmc: core: Introduce host claiming by context
Date
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>
---
drivers/mmc/core/core.c | 92 ++++++++++++++++++++++++++++++++++++++++++++----
drivers/mmc/core/core.h | 6 ++++
include/linux/mmc/host.h | 7 +++-
3 files changed, 97 insertions(+), 8 deletions(-)

diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index 66c9cf49ad2f..09fdc467b804 100644
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -832,9 +832,38 @@ 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
+ * __mmc_ctx_task_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
+ * @task: task that claims the host or NULL in which case @ctx must be
+ * provided
* @abort: whether or not the operation should be aborted
*
* Claim a host for a set of operations. If @abort is non null and
@@ -842,7 +871,8 @@ unsigned int mmc_align_data_size(struct mmc_card *card, unsigned int sz)
* 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)
+static int __mmc_ctx_task_claim_host(struct mmc_host *host, struct mmc_ctx *ctx,
+ struct task_struct *task, atomic_t *abort)
{
DECLARE_WAITQUEUE(wait, current);
unsigned long flags;
@@ -856,7 +886,7 @@ 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 +895,7 @@ 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;
@@ -879,8 +909,19 @@ int __mmc_claim_host(struct mmc_host *host, atomic_t *abort)

return stop;
}
+
+int __mmc_claim_host(struct mmc_host *host, atomic_t *abort)
+{
+ return __mmc_ctx_task_claim_host(host, NULL, current, abort);
+}
EXPORT_SYMBOL(__mmc_claim_host);

+void mmc_ctx_claim_host(struct mmc_host *host, struct mmc_ctx *ctx)
+{
+ __mmc_ctx_task_claim_host(host, ctx, NULL, NULL);
+}
+EXPORT_SYMBOL(mmc_ctx_claim_host);
+
/**
* mmc_release_host - release a host
* @host: mmc host to release
@@ -888,18 +929,17 @@ int __mmc_claim_host(struct mmc_host *host, atomic_t *abort)
* Release a MMC host, allowing others to claim the host
* for their operations.
*/
-void mmc_release_host(struct mmc_host *host)
+static void __mmc_release_host(struct mmc_host *host)
{
unsigned long flags;

- WARN_ON(!host->claimed);
-
spin_lock_irqsave(&host->lock, flags);
if (--host->claim_cnt) {
/* Release for nested claim */
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);
@@ -907,8 +947,23 @@ void mmc_release_host(struct mmc_host *host)
pm_runtime_put_autosuspend(mmc_dev(host));
}
}
+
+void mmc_release_host(struct mmc_host *host)
+{
+ WARN_ON(!host->claimed);
+
+ __mmc_release_host(host);
+}
EXPORT_SYMBOL(mmc_release_host);

+void mmc_ctx_release_host(struct mmc_host *host, struct mmc_ctx *ctx)
+{
+ WARN_ON(!host->claimed || host->claimer != ctx);
+
+ __mmc_release_host(host);
+}
+EXPORT_SYMBOL(mmc_ctx_release_host);
+
/*
* This is a helper function, which fetches a runtime pm reference for the
* card device and also claims the host.
@@ -921,6 +976,17 @@ void mmc_get_card(struct mmc_card *card)
EXPORT_SYMBOL(mmc_get_card);

/*
+ * This is a helper function, which fetches a runtime pm reference for the
+ * card device and also claims the host for the mmc context.
+ */
+void mmc_ctx_get_card(struct mmc_card *card, struct mmc_ctx *ctx)
+{
+ pm_runtime_get_sync(&card->dev);
+ mmc_ctx_claim_host(card->host, ctx);
+}
+EXPORT_SYMBOL(mmc_ctx_get_card);
+
+/*
* This is a helper function, which releases the host and drops the runtime
* pm reference for the card device.
*/
@@ -933,6 +999,18 @@ void mmc_put_card(struct mmc_card *card)
EXPORT_SYMBOL(mmc_put_card);

/*
+ * This is a helper function, which releases the host and drops the runtime
+ * pm reference for the card device.
+ */
+void mmc_ctx_put_card(struct mmc_card *card, struct mmc_ctx *ctx)
+{
+ mmc_ctx_release_host(card->host, ctx);
+ pm_runtime_mark_last_busy(&card->dev);
+ pm_runtime_put_autosuspend(&card->dev);
+}
+EXPORT_SYMBOL(mmc_ctx_put_card);
+
+/*
* Internal function that does the actual ios call to the host driver,
* optionally printing some debug output.
*/
diff --git a/drivers/mmc/core/core.h b/drivers/mmc/core/core.h
index ca861091a776..a294c836a143 100644
--- a/drivers/mmc/core/core.h
+++ b/drivers/mmc/core/core.h
@@ -144,4 +144,10 @@ static inline void mmc_claim_host(struct mmc_host *host)
__mmc_claim_host(host, NULL);
}

+void mmc_ctx_claim_host(struct mmc_host *host, struct mmc_ctx *ctx);
+void mmc_ctx_release_host(struct mmc_host *host, struct mmc_ctx *ctx);
+
+void mmc_ctx_get_card(struct mmc_card *card, struct mmc_ctx *ctx);
+void mmc_ctx_put_card(struct mmc_card *card, struct mmc_ctx *ctx);
+
#endif
diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
index f3f2d07feb2a..228a493c3b25 100644
--- a/include/linux/mmc/host.h
+++ b/include/linux/mmc/host.h
@@ -255,6 +255,10 @@ struct mmc_supply {
struct regulator *vqmmc; /* Optional Vccq supply */
};

+struct mmc_ctx {
+ struct task_struct *task;
+};
+
struct mmc_host {
struct device *parent;
struct device class_dev;
@@ -388,8 +392,9 @@ struct mmc_host {
struct mmc_card *card; /* device attached to this host */

wait_queue_head_t wq;
- struct task_struct *claimer; /* task that has host claimed */
+ struct mmc_ctx *claimer; /* context that has host claimed */
int claim_cnt; /* "claim" nesting count */
+ struct mmc_ctx default_ctx; /* default context */

struct delayed_work detect;
int detect_change; /* card detect flag */
--
1.9.1
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