sdio: allow for mmc_claim_host to be aborted

It is sometimes necessary to give up on trying to claim the host lock,
especially if that happens in a thread that has to be stopped.

While at it, fix the description for mmc_claim_host() which was wrong.

Signed-off-by: Nicolas Pitre <npitre@mvista.com>
Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>

2 files changed, 28 insertions, 7 deletions

diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index b8f27e5ade97..d1e4b0849e39 100644
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -273,15 +273,20 @@ void mmc_set_data_timeout(struct mmc_data *data, const struct mmc_card *card)
 EXPORT_SYMBOL(mmc_set_data_timeout);
 
 /**
- *      mmc_claim_host - exclusively claim a host
+ *      __mmc_claim_host - exclusively claim a host
  *      @host: mmc host to claim
+ *      @abort: whether or not the operation should be aborted
  *
- *      Claim a host for a set of operations.
+ *      Claim a host for a set of operations.  If @abort is non null and
+ *      dereference a non-zero value then this will return prematurely with
+ *      that non-zero value without acquiring the lock.  Returns zero
+ *      with the lock held otherwise.
  */
-void mmc_claim_host(struct mmc_host *host)
+int __mmc_claim_host(struct mmc_host *host, atomic_t *abort)
 {
         DECLARE_WAITQUEUE(wait, current);
         unsigned long flags;
+        int stop;
 
         might_sleep();
 
@@ -289,19 +294,24 @@ void mmc_claim_host(struct mmc_host *host)
         spin_lock_irqsave(&host->lock, flags);
         while (1) {
                 set_current_state(TASK_UNINTERRUPTIBLE);
-                if (!host->claimed)
+                stop = abort ? atomic_read(abort) : 0;
+                if (stop || !host->claimed)
                         break;
                 spin_unlock_irqrestore(&host->lock, flags);
                 schedule();
                 spin_lock_irqsave(&host->lock, flags);
         }
         set_current_state(TASK_RUNNING);
-        host->claimed = 1;
+        if (!stop)
+                host->claimed = 1;
+        else
+                wake_up(&host->wq);
         spin_unlock_irqrestore(&host->lock, flags);
         remove_wait_queue(&host->wq, &wait);
+        return stop;
 }
 
-EXPORT_SYMBOL(mmc_claim_host);
+EXPORT_SYMBOL(__mmc_claim_host);
 
 /**
  *      mmc_release_host - release a host
diff --git a/include/linux/mmc/core.h b/include/linux/mmc/core.h
index 43a92736be63..8945da9b54fa 100644
--- a/include/linux/mmc/core.h
+++ b/include/linux/mmc/core.h
@@ -114,7 +114,18 @@ extern int mmc_wait_for_app_cmd(struct mmc_host *, struct mmc_card *,
 
 extern void mmc_set_data_timeout(struct mmc_data *, const struct mmc_card *);
 
-extern void mmc_claim_host(struct mmc_host *host);
+extern int __mmc_claim_host(struct mmc_host *host, atomic_t *abort);
 extern void mmc_release_host(struct mmc_host *host);
 
+/**
+ *      mmc_claim_host - exclusively claim a host
+ *      @host: mmc host to claim
+ *
+ *      Claim a host for a set of operations.
+ */
+static inline void mmc_claim_host(struct mmc_host *host)
+{
+        __mmc_claim_host(host, NULL);
+}
+
 #endif