[PATCH] mmc: use own work queue

The MMC layer uses the standard work queue for doing card detection.  As this
queue is shared with other crucial subsystems, the effects of a long (and
perhaps buggy) detection can cause the system to be unusable.  E.g.  the
keyboard stops working while the detection routine is running.

The solution is to add a specific mmc work queue to run the detection code in.
This is similar to how other subsystems handle detection (a full kernel
thread is the most common theme).

Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>
Cc: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 34 insertions, 1 deletions

diff --git a/drivers/mmc/mmc_sysfs.c b/drivers/mmc/mmc_sysfs.c
index a2a35fd946e..10cc9734eaa 100644
--- a/drivers/mmc/mmc_sysfs.c
+++ b/drivers/mmc/mmc_sysfs.c
@@ -13,6 +13,7 @@
 #include <linux/init.h>
 #include <linux/device.h>
 #include <linux/idr.h>
+#include <linux/workqueue.h>
 
 #include <linux/mmc/card.h>
 #include <linux/mmc/host.h>
@@ -317,10 +318,41 @@ void mmc_free_host_sysfs(struct mmc_host *host)
 	class_device_put(&host->class_dev);
 }
 
+static struct workqueue_struct *workqueue;
+
+/*
+ * Internal function. Schedule work in the MMC work queue.
+ */
+int mmc_schedule_work(struct work_struct *work)
+{
+	return queue_work(workqueue, work);
+}
+
+/*
+ * Internal function. Schedule delayed work in the MMC work queue.
+ */
+int mmc_schedule_delayed_work(struct work_struct *work, unsigned long delay)
+{
+	return queue_delayed_work(workqueue, work, delay);
+}
+
+/*
+ * Internal function. Flush all scheduled work from the MMC work queue.
+ */
+void mmc_flush_scheduled_work(void)
+{
+	flush_workqueue(workqueue);
+}
 
 static int __init mmc_init(void)
 {
-	int ret = bus_register(&mmc_bus_type);
+	int ret;
+
+	workqueue = create_singlethread_workqueue("kmmcd");
+	if (!workqueue)
+		return -ENOMEM;
+
+	ret = bus_register(&mmc_bus_type);
 	if (ret == 0) {
 		ret = class_register(&mmc_host_class);
 		if (ret)
@@ -333,6 +365,7 @@ static void __exit mmc_exit(void)
 {
 	class_unregister(&mmc_host_class);
 	bus_unregister(&mmc_bus_type);
+	destroy_workqueue(workqueue);
 }
 
 module_init(mmc_init);