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[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>
This commit is contained in:
mochel@digitalimplant.org 2005-03-21 10:41:04 -08:00 committed by Greg Kroah-Hartman
parent eb51b65005
commit af70316af1
5 changed files with 24 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

14
drivers/base/bus.c
View File

@ -283,18 +283,22 @@ void device_bind_driver(struct device * dev)
*/
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 driver_attach(struct device_driver * drv)
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");
@ -394,6 +401,7 @@ void device_release_driver(struct device * dev)
drv->remove(dev);
dev->driver = NULL;
}
up(&dev->sem);
}

1
drivers/base/core.c
View File

@ -212,6 +212,7 @@ void device_initialize(struct device *dev)
INIT_LIST_HEAD(&dev->driver_list);
INIT_LIST_HEAD(&dev->bus_list);
INIT_LIST_HEAD(&dev->dma_pools);
init_MUTEX(&dev->sem);
}
/**

8
drivers/base/power/resume.c
View File

@ -22,6 +22,9 @@ extern int sysdev_resume(void);
int resume_device(struct device * dev)
{
int error = 0;
down(&dev->sem);
if (dev->power.pm_parent
&& dev->power.pm_parent->power.power_state) {
dev_err(dev, "PM: resume from %d, parent %s still %d\n",
@ -31,9 +34,10 @@ int resume_device(struct device * dev)
}
if (dev->bus && dev->bus->resume) {
dev_dbg(dev,"resuming\n");
return dev->bus->resume(dev);
error = dev->bus->resume(dev);
}
return 0;
up(&dev->sem);
return error;
}

3
drivers/base/power/suspend.c
View File

@ -39,6 +39,7 @@ int suspend_device(struct device * dev, pm_message_t state)
{
int error = 0;
down(&dev->sem);
if (dev->power.power_state) {
dev_dbg(dev, "PM: suspend %d-->%d\n",
dev->power.power_state, state);
@ -58,7 +59,7 @@ int suspend_device(struct device * dev, pm_message_t state)
dev_dbg(dev, "suspending\n");
error = dev->bus->suspend(dev, state);
}
up(&dev->sem);
return error;
}

4
include/linux/device.h
View File

@ -264,6 +264,10 @@ struct device {
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 */