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@ 2005-01-18 0:07 Greg KH
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From: Greg KH @ 2005-01-18 0:07 UTC (permalink / raw)
To: linux-kernel
Subject [RFC] sysdev: change locking to use a class based spinlock
Reply-To:
Here's another patch in my steps of removing the use of the subsystem
rwsem lock. I've converted the sysdev subsystem here to use a spinlock
(instead of a semaphore, like my previous class patch did, I'll go
change that later too.)
The patch is against 2.6.11-rc1. Any comments would be appreciated.
thanks,
greg k-h
-------
sysdev: change locking to use a class based spinlock
Use the new lock, and not the global subsystem lock. This is a step in
removing the rwsem from subsystems, and should allow sysdevs to now be
able to add and remove themselves from within their function callbacks.
Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>
--- 1.28/drivers/base/sys.c 2004-10-20 09:47:44 -07:00
+++ edited/drivers/base/sys.c 2005-01-17 15:37:06 -08:00
@@ -79,13 +79,14 @@ EXPORT_SYMBOL_GPL(sysdev_remove_file);
/*
* declare system_subsys
*/
-decl_subsys(system, &ktype_sysdev, NULL);
+static decl_subsys(system, &ktype_sysdev, NULL);
int sysdev_class_register(struct sysdev_class * cls)
{
pr_debug("Registering sysdev class '%s'\n",
kobject_name(&cls->kset.kobj));
INIT_LIST_HEAD(&cls->drivers);
+ spin_lock_init(&cls->lock);
cls->kset.subsys = &system_subsys;
kset_set_kset_s(cls, system_subsys);
return kset_register(&cls->kset);
@@ -103,6 +104,7 @@ EXPORT_SYMBOL_GPL(sysdev_class_unregiste
static LIST_HEAD(global_drivers);
+static DEFINE_SPINLOCK(global_drivers_lock);
/**
* sysdev_driver_register - Register auxillary driver
@@ -119,19 +121,22 @@ static LIST_HEAD(global_drivers);
int sysdev_driver_register(struct sysdev_class * cls,
struct sysdev_driver * drv)
{
- down_write(&system_subsys.rwsem);
if (cls && kset_get(&cls->kset)) {
+ spin_lock(&cls->lock);
list_add_tail(&drv->entry, &cls->drivers);
+ spin_unlock(&cls->lock);
/* If devices of this class already exist, tell the driver */
if (drv->add) {
- struct sys_device *dev;
- list_for_each_entry(dev, &cls->kset.list, kobj.entry)
+ struct sys_device *dev, *temp;
+ list_for_each_entry_safe(dev, temp, &cls->kset.list, kobj.entry)
drv->add(dev);
}
- } else
+ } else {
+ spin_lock(&global_drivers_lock);
list_add_tail(&drv->entry, &global_drivers);
- up_write(&system_subsys.rwsem);
+ spin_unlock(&global_drivers_lock);
+ }
return 0;
}
@@ -144,17 +149,21 @@ int sysdev_driver_register(struct sysdev
void sysdev_driver_unregister(struct sysdev_class * cls,
struct sysdev_driver * drv)
{
- down_write(&system_subsys.rwsem);
+ /* we don't know which list the drv is on, so lock both of them */
+ spin_lock(&cls->lock);
+ spin_lock(&global_drivers_lock);
list_del_init(&drv->entry);
+ spin_unlock(&global_drivers_lock);
+ spin_unlock(&cls->lock);
+
if (cls) {
if (drv->remove) {
- struct sys_device *dev;
- list_for_each_entry(dev, &cls->kset.list, kobj.entry)
+ struct sys_device *dev, *temp;
+ list_for_each_entry_safe(dev, temp, &cls->kset.list, kobj.entry)
drv->remove(dev);
}
kset_put(&cls->kset);
}
- up_write(&system_subsys.rwsem);
}
EXPORT_SYMBOL_GPL(sysdev_driver_register);
@@ -191,44 +200,40 @@ int sysdev_register(struct sys_device *
error = kobject_register(&sysdev->kobj);
if (!error) {
- struct sysdev_driver * drv;
+ struct sysdev_driver *drv, *temp;
- down_write(&system_subsys.rwsem);
/* Generic notification is implicit, because it's that
* code that should have called us.
*/
/* Notify global drivers */
- list_for_each_entry(drv, &global_drivers, entry) {
+ list_for_each_entry_safe(drv, temp, &global_drivers, entry) {
if (drv->add)
drv->add(sysdev);
}
/* Notify class auxillary drivers */
- list_for_each_entry(drv, &cls->drivers, entry) {
+ list_for_each_entry_safe(drv, temp, &cls->drivers, entry) {
if (drv->add)
drv->add(sysdev);
}
- up_write(&system_subsys.rwsem);
}
return error;
}
void sysdev_unregister(struct sys_device * sysdev)
{
- struct sysdev_driver * drv;
+ struct sysdev_driver *drv, *temp;
- down_write(&system_subsys.rwsem);
- list_for_each_entry(drv, &global_drivers, entry) {
+ list_for_each_entry_safe(drv, temp, &global_drivers, entry) {
if (drv->remove)
drv->remove(sysdev);
}
- list_for_each_entry(drv, &sysdev->cls->drivers, entry) {
+ list_for_each_entry_safe(drv, temp, &sysdev->cls->drivers, entry) {
if (drv->remove)
drv->remove(sysdev);
}
- up_write(&system_subsys.rwsem);
kobject_unregister(&sysdev->kobj);
}
@@ -251,30 +256,29 @@ void sysdev_unregister(struct sys_device
void sysdev_shutdown(void)
{
- struct sysdev_class * cls;
+ struct sysdev_class *cls;
pr_debug("Shutting Down System Devices\n");
- down_write(&system_subsys.rwsem);
list_for_each_entry_reverse(cls, &system_subsys.kset.list,
kset.kobj.entry) {
- struct sys_device * sysdev;
+ struct sys_device *sysdev, *temp_dev;
pr_debug("Shutting down type '%s':\n",
kobject_name(&cls->kset.kobj));
- list_for_each_entry(sysdev, &cls->kset.list, kobj.entry) {
- struct sysdev_driver * drv;
+ list_for_each_entry_safe(sysdev, temp_dev, &cls->kset.list, kobj.entry) {
+ struct sysdev_driver *drv, *temp_drv;
pr_debug(" %s\n", kobject_name(&sysdev->kobj));
/* Call global drivers first. */
- list_for_each_entry(drv, &global_drivers, entry) {
+ list_for_each_entry_safe(drv, temp_drv, &global_drivers, entry) {
if (drv->shutdown)
drv->shutdown(sysdev);
}
/* Call auxillary drivers next. */
- list_for_each_entry(drv, &cls->drivers, entry) {
+ list_for_each_entry_safe(drv, temp_drv, &cls->drivers, entry) {
if (drv->shutdown)
drv->shutdown(sysdev);
}
@@ -284,7 +288,6 @@ void sysdev_shutdown(void)
cls->shutdown(sysdev);
}
}
- up_write(&system_subsys.rwsem);
}
@@ -309,23 +312,23 @@ int sysdev_suspend(u32 state)
list_for_each_entry_reverse(cls, &system_subsys.kset.list,
kset.kobj.entry) {
- struct sys_device * sysdev;
+ struct sys_device *sysdev, *temp_dev;
pr_debug("Suspending type '%s':\n",
kobject_name(&cls->kset.kobj));
- list_for_each_entry(sysdev, &cls->kset.list, kobj.entry) {
- struct sysdev_driver * drv;
+ list_for_each_entry_safe(sysdev, temp_dev, &cls->kset.list, kobj.entry) {
+ struct sysdev_driver *drv, *temp_drv;
pr_debug(" %s\n", kobject_name(&sysdev->kobj));
/* Call global drivers first. */
- list_for_each_entry(drv, &global_drivers, entry) {
+ list_for_each_entry_safe(drv, temp_drv, &global_drivers, entry) {
if (drv->suspend)
drv->suspend(sysdev, state);
}
/* Call auxillary drivers next. */
- list_for_each_entry(drv, &cls->drivers, entry) {
+ list_for_each_entry_safe(drv, temp_drv, &cls->drivers, entry) {
if (drv->suspend)
drv->suspend(sysdev, state);
}
@@ -355,13 +358,13 @@ int sysdev_resume(void)
pr_debug("Resuming System Devices\n");
list_for_each_entry(cls, &system_subsys.kset.list, kset.kobj.entry) {
- struct sys_device * sysdev;
+ struct sys_device *sysdev, *temp_dev;
pr_debug("Resuming type '%s':\n",
kobject_name(&cls->kset.kobj));
- list_for_each_entry(sysdev, &cls->kset.list, kobj.entry) {
- struct sysdev_driver * drv;
+ list_for_each_entry_safe(sysdev, temp_dev, &cls->kset.list, kobj.entry) {
+ struct sysdev_driver *drv, *temp_drv;
pr_debug(" %s\n", kobject_name(&sysdev->kobj));
/* First, call the class-specific one */
@@ -369,13 +372,13 @@ int sysdev_resume(void)
cls->resume(sysdev);
/* Call auxillary drivers next. */
- list_for_each_entry(drv, &cls->drivers, entry) {
+ list_for_each_entry_safe(drv, temp_drv, &cls->drivers, entry) {
if (drv->resume)
drv->resume(sysdev);
}
/* Call global drivers. */
- list_for_each_entry(drv, &global_drivers, entry) {
+ list_for_each_entry_safe(drv, temp_drv, &global_drivers, entry) {
if (drv->resume)
drv->resume(sysdev);
}
===== include/linux/sysdev.h 1.6 vs edited =====
--- 1.6/include/linux/sysdev.h 2004-03-04 08:57:52 -08:00
+++ edited/include/linux/sysdev.h 2005-01-17 14:46:50 -08:00
@@ -22,12 +22,14 @@
#define _SYSDEV_H_
#include <linux/kobject.h>
+#include <linux/spinlock.h>
struct sys_device;
struct sysdev_class {
struct list_head drivers;
+ spinlock_t lock; /* locks the list for this class */
/* Default operations for these types of devices */
int (*shutdown)(struct sys_device *);
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