[PATCH] Add a semaphore to struct device to synchronize calls to its driver.
This adds a per-device semaphore that is taken before every call from the core to a
driver method. This prevents e.g. simultaneous calls to the ->suspend() or ->resume()
and ->probe() or ->release(), potentially saving a whole lot of headaches.
It also moves us a step closer to removing the bus rwsem, since it protects the fields
in struct device that are modified by the core.
Signed-off-by: Patrick Mochel <mochel@digitalimplant.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/include/linux/device.h b/include/linux/device.h
index 68a9535..195b327 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -264,6 +264,10 @@
struct kobject kobj;
char bus_id[BUS_ID_SIZE]; /* position on parent bus */
+ struct semaphore sem; /* semaphore to synchronize calls to
+ * its driver.
+ */
+
struct bus_type * bus; /* type of bus device is on */
struct device_driver *driver; /* which driver has allocated this
device */