From foo@baz Tue Apr 9 12:12:43 2002
To: Greg KH <gregkh@suse.de>
Date: 21 Mar 2005 10:41:04 -08:00
From: mochel@digitalimplant.org
Subject: [driver core] 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>
Index: linux-2.6.12-rc2/drivers/base/bus.c
===================================================================
--- linux-2.6.12-rc2.orig/drivers/base/bus.c 2005-04-05 14:30:57.000000000 -0700
+++ linux-2.6.12-rc2/drivers/base/bus.c 2005-04-05 14:33:43.000000000 -0700
@@ -283,18 +283,22 @@
*/
int driver_probe_device(struct device_driver * drv, struct device * dev)
{
+ int error = 0;
+
if (drv->bus->match && !drv->bus->match(dev, drv))
return -ENODEV;
+ down(&dev->sem);
dev->driver = drv;
if (drv->probe) {
- int error = drv->probe(dev);
+ error = drv->probe(dev);
if (error) {
dev->driver = NULL;
+ up(&dev->sem);
return error;
}
}
-
+ up(&dev->sem);
device_bind_driver(dev);
return 0;
}
@@ -385,7 +389,10 @@
void device_release_driver(struct device * dev)
{
- struct device_driver * drv = dev->driver;
+ struct device_driver * drv;
+
+ down(&dev->sem);
+ drv = dev->driver;
if (drv) {
sysfs_remove_link(&drv->kobj, kobject_name(&dev->kobj));
sysfs_remove_link(&dev->kobj, "driver");
@@ -395,6 +402,7 @@
drv->remove(dev);
dev->driver = NULL;
}
+ up(&dev->sem);
}
Index: linux-2.6.12-rc2/drivers/base/core.c
===================================================================
--- linux-2.6.12-rc2.orig/drivers/base/core.c 2005-04-05 14:33:40.000000000 -0700
+++ linux-2.6.12-rc2/drivers/base/core.c 2005-04-05 14:33:43.000000000 -0700
@@ -215,6 +215,7 @@
INIT_LIST_HEAD(&dev->driver_list);
INIT_LIST_HEAD(&dev->bus_list);
INIT_LIST_HEAD(&dev->dma_pools);
+ init_MUTEX(&dev->sem);
}
/**
Index: linux-2.6.12-rc2/drivers/base/power/resume.c
===================================================================
--- linux-2.6.12-rc2.orig/drivers/base/power/resume.c 2005-04-05 14:30:57.000000000 -0700
+++ linux-2.6.12-rc2/drivers/base/power/resume.c 2005-04-05 14:33:43.000000000 -0700
@@ -22,9 +22,13 @@
int resume_device(struct device * dev)
{
+ int error = 0;
+
+ down(&dev->sem);
if (dev->bus && dev->bus->resume)
- return dev->bus->resume(dev);
- return 0;
+ error = dev->bus->resume(dev);
+ up(&dev->sem);
+ return error;
}
Index: linux-2.6.12-rc2/drivers/base/power/suspend.c
===================================================================
--- linux-2.6.12-rc2.orig/drivers/base/power/suspend.c 2005-04-05 14:30:57.000000000 -0700
+++ linux-2.6.12-rc2/drivers/base/power/suspend.c 2005-04-05 14:33:43.000000000 -0700
@@ -41,11 +41,11 @@
dev_dbg(dev, "suspending\n");
+ down(&dev->sem);
dev->power.prev_state = dev->power.power_state;
-
if (dev->bus && dev->bus->suspend && !dev->power.power_state)
error = dev->bus->suspend(dev, state);
-
+ up(&dev->sem);
return error;
}
Index: linux-2.6.12-rc2/include/linux/device.h
===================================================================
--- linux-2.6.12-rc2.orig/include/linux/device.h 2005-04-05 14:33:38.000000000 -0700
+++ linux-2.6.12-rc2/include/linux/device.h 2005-04-05 14:33:43.000000000 -0700
@@ -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 */