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SubjectRe: [PATCH 0/7] convert semaphore to mutex in struct class
On Sun, Jan 06, 2008 at 07:41:29PM +0100, Stefan Richter wrote:
> Dave Young wrote:
> > Convert semaphore to mutex in struct class.
> > All the patches in this series should be applyed simultaneously
>
> Therefore you eventually need to repost it as a single patch. It can't
> go into one of the maintainer trees otherwise, because they only take
> fully bijectable patches. (Kernel must build and run at any point in
> between any patch series.)
>
> > toc:
> > ---
> > 1-driver-core-struct-class-convert-semaphore-to-mutex.patch
> > 2-i2c-struct-class-convert-semaphore-to-mutex.patch
> > 3-ieee1394-struct-class-convert-semaphore-to-mutex.patch
> > 4-power-struct-class-convert-semaphore-to-mutex.patch
> > 5-rtc-struct-class-convert-semaphore-to-mutex.patch
> > 6-scsi-struct-class-convert-semaphore-to-mutex.patch
> > 7-spi-struct-class-convert-semaphore-to-mutex.patch
>
> I was going to test it at runtime on top of 2.6.24-rc6, but the first
> and second patch depend on stuff in -mm. So, my laziness wins for now,
> as -mm is not my cup of tea.
>
> About your changelog:
>
> "xyz: convert semaphore to mutex in struct class
>
> Use mutex instead of semaphore in struct class.
>
> Signed-off-by: Dave Young <hidave.darkstar@gmail.com>"
>
> You don't need the second line because it says the same as the first
> line. Either kill it, or replace it by an explanation _why_ the
> semaphore is to be replaced by mutex. (I guess you do it because they
> are lighter-weight, both in semantics and in implementation, and because
> there are better facilities to debug mutexes...)

Thanks for your comment, I rewrite it for 2.6.24-rc7 as a all-in-one patch, please see following. Drop i2c maintainer and list in cc because there's no changes about i2c in this patch:

Convert semaphore to mutex in struct class

Signed-off-by: Dave Young <hidave.darkstar@gmail.com>

---
drivers/base/class.c | 22 ++++++++++----------
drivers/base/core.c | 18 +++++++----------
drivers/ieee1394/nodemgr.c | 40 +++++++++++++++++++-------------------
drivers/power/apm_power.c | 6 ++---
drivers/power/power_supply_core.c | 8 +++----
drivers/rtc/interface.c | 4 +--
drivers/scsi/hosts.c | 4 +--
drivers/spi/spi.c | 4 +--
include/linux/device.h | 3 +-
9 files changed, 54 insertions(+), 55 deletions(-)

diff -upr a/linux-2.6.24-rc7/drivers/base/class.c linux-2.6.24-rc7/drivers/base/class.c
--- a/linux-2.6.24-rc7/drivers/base/class.c 2008-01-07 08:56:05.000000000 +0800
+++ linux-2.6.24-rc7/drivers/base/class.c 2008-01-07 09:12:49.000000000 +0800
@@ -144,7 +144,7 @@ int class_register(struct class * cls)
INIT_LIST_HEAD(&cls->devices);
INIT_LIST_HEAD(&cls->interfaces);
kset_init(&cls->class_dirs);
- init_MUTEX(&cls->sem);
+ mutex_init(&cls->mutex);
error = kobject_set_name(&cls->subsys.kobj, "%s", cls->name);
if (error)
return error;
@@ -617,13 +617,13 @@ int class_device_add(struct class_device
kobject_uevent(&class_dev->kobj, KOBJ_ADD);

/* notify any interfaces this device is now here */
- down(&parent_class->sem);
+ mutex_lock_nested(&parent_class->mutex, SINGLE_DEPTH_NESTING);
list_add_tail(&class_dev->node, &parent_class->children);
list_for_each_entry(class_intf, &parent_class->interfaces, node) {
if (class_intf->add)
class_intf->add(class_dev, class_intf);
}
- up(&parent_class->sem);
+ mutex_unlock(&parent_class->mutex);

goto out1;

@@ -725,12 +725,12 @@ void class_device_del(struct class_devic
struct class_interface *class_intf;

if (parent_class) {
- down(&parent_class->sem);
+ mutex_lock(&parent_class->mutex);
list_del_init(&class_dev->node);
list_for_each_entry(class_intf, &parent_class->interfaces, node)
if (class_intf->remove)
class_intf->remove(class_dev, class_intf);
- up(&parent_class->sem);
+ mutex_unlock(&parent_class->mutex);
}

if (class_dev->dev) {
@@ -772,14 +772,14 @@ void class_device_destroy(struct class *
struct class_device *class_dev = NULL;
struct class_device *class_dev_tmp;

- down(&cls->sem);
+ mutex_lock(&cls->mutex);
list_for_each_entry(class_dev_tmp, &cls->children, node) {
if (class_dev_tmp->devt == devt) {
class_dev = class_dev_tmp;
break;
}
}
- up(&cls->sem);
+ mutex_unlock(&cls->mutex);

if (class_dev)
class_device_unregister(class_dev);
@@ -812,7 +812,7 @@ int class_interface_register(struct clas
if (!parent)
return -EINVAL;

- down(&parent->sem);
+ mutex_lock(&parent->mutex);
list_add_tail(&class_intf->node, &parent->interfaces);
if (class_intf->add) {
list_for_each_entry(class_dev, &parent->children, node)
@@ -822,7 +822,7 @@ int class_interface_register(struct clas
list_for_each_entry(dev, &parent->devices, node)
class_intf->add_dev(dev, class_intf);
}
- up(&parent->sem);
+ mutex_unlock(&parent->mutex);

return 0;
}
@@ -836,7 +836,7 @@ void class_interface_unregister(struct c
if (!parent)
return;

- down(&parent->sem);
+ mutex_lock(&parent->mutex);
list_del_init(&class_intf->node);
if (class_intf->remove) {
list_for_each_entry(class_dev, &parent->children, node)
@@ -846,7 +846,7 @@ void class_interface_unregister(struct c
list_for_each_entry(dev, &parent->devices, node)
class_intf->remove_dev(dev, class_intf);
}
- up(&parent->sem);
+ mutex_unlock(&parent->mutex);

class_put(parent);
}
diff -upr a/linux-2.6.24-rc7/drivers/base/core.c linux-2.6.24-rc7/drivers/base/core.c
--- a/linux-2.6.24-rc7/drivers/base/core.c 2008-01-07 08:56:05.000000000 +0800
+++ linux-2.6.24-rc7/drivers/base/core.c 2008-01-07 09:39:11.000000000 +0800
@@ -19,8 +19,6 @@
#include <linux/kdev_t.h>
#include <linux/notifier.h>

-#include <asm/semaphore.h>
-
#include "base.h"
#include "power/power.h"

@@ -783,7 +781,7 @@ int device_add(struct device *dev)
klist_add_tail(&dev->knode_parent, &parent->klist_children);

if (dev->class) {
- down(&dev->class->sem);
+ mutex_lock(&dev->class->mutex);
/* tie the class to the device */
list_add_tail(&dev->node, &dev->class->devices);

@@ -791,7 +789,7 @@ int device_add(struct device *dev)
list_for_each_entry(class_intf, &dev->class->interfaces, node)
if (class_intf->add_dev)
class_intf->add_dev(dev, class_intf);
- up(&dev->class->sem);
+ mutex_unlock(&dev->class->mutex);
}
Done:
put_device(dev);
@@ -928,14 +926,14 @@ void device_del(struct device * dev)
sysfs_remove_link(&dev->kobj, "device");
}

- down(&dev->class->sem);
+ mutex_lock(&dev->class->mutex);
/* notify any interfaces that the device is now gone */
list_for_each_entry(class_intf, &dev->class->interfaces, node)
if (class_intf->remove_dev)
class_intf->remove_dev(dev, class_intf);
/* remove the device from the class list */
list_del_init(&dev->node);
- up(&dev->class->sem);
+ mutex_unlock(&dev->class->mutex);

/* If we live in a parent class-directory, unreference it */
if (dev->kobj.parent->kset == &dev->class->class_dirs) {
@@ -946,7 +944,7 @@ void device_del(struct device * dev)
* if we are the last child of our class, delete
* our class-directory at this parent
*/
- down(&dev->class->sem);
+ mutex_lock(&dev->class->mutex);
list_for_each_entry(d, &dev->class->devices, node) {
if (d == dev)
continue;
@@ -959,7 +957,7 @@ void device_del(struct device * dev)
kobject_del(dev->kobj.parent);

kobject_put(dev->kobj.parent);
- up(&dev->class->sem);
+ mutex_unlock(&dev->class->mutex);
}
}
device_remove_file(dev, &uevent_attr);
@@ -1168,14 +1166,14 @@ void device_destroy(struct class *class,
struct device *dev = NULL;
struct device *dev_tmp;

- down(&class->sem);
+ mutex_lock(&class->mutex);
list_for_each_entry(dev_tmp, &class->devices, node) {
if (dev_tmp->devt == devt) {
dev = dev_tmp;
break;
}
}
- up(&class->sem);
+ mutex_unlock(&class->mutex);

if (dev)
device_unregister(dev);
diff -upr a/linux-2.6.24-rc7/drivers/ieee1394/nodemgr.c linux-2.6.24-rc7/drivers/ieee1394/nodemgr.c
--- a/linux-2.6.24-rc7/drivers/ieee1394/nodemgr.c 2008-01-07 08:56:06.000000000 +0800
+++ linux-2.6.24-rc7/drivers/ieee1394/nodemgr.c 2008-01-07 09:26:47.000000000 +0800
@@ -733,16 +733,16 @@ static void nodemgr_remove_uds(struct no
struct unit_directory *tmp, *ud;

/* Iteration over nodemgr_ud_class.devices has to be protected by
- * nodemgr_ud_class.sem, but device_unregister() will eventually
- * take nodemgr_ud_class.sem too. Therefore pick out one ud at a time,
- * release the semaphore, and then unregister the ud. Since this code
+ * nodemgr_ud_class.mutex, but device_unregister() will eventually
+ * take nodemgr_ud_class.mutex too. Therefore pick out one ud at a time,
+ * unlock the mutex, and then unregister the ud. Since this code
* may be called from other contexts besides the knodemgrds, protect the
- * gap after release of the semaphore by nodemgr_serialize_remove_uds.
+ * gap after unlock of the mutex by nodemgr_serialize_remove_uds.
*/
mutex_lock(&nodemgr_serialize_remove_uds);
for (;;) {
ud = NULL;
- down(&nodemgr_ud_class.sem);
+ mutex_lock(&nodemgr_ud_class.mutex);
list_for_each_entry(dev, &nodemgr_ud_class.devices, node) {
tmp = container_of(dev, struct unit_directory,
unit_dev);
@@ -751,7 +751,7 @@ static void nodemgr_remove_uds(struct no
break;
}
}
- up(&nodemgr_ud_class.sem);
+ mutex_unlock(&nodemgr_ud_class.mutex);
if (ud == NULL)
break;
device_unregister(&ud->unit_dev);
@@ -888,7 +888,7 @@ static struct node_entry *find_entry_by_
struct device *dev;
struct node_entry *ne, *ret_ne = NULL;

- down(&nodemgr_ne_class.sem);
+ mutex_lock(&nodemgr_ne_class.mutex);
list_for_each_entry(dev, &nodemgr_ne_class.devices, node) {
ne = container_of(dev, struct node_entry, node_dev);

@@ -897,7 +897,7 @@ static struct node_entry *find_entry_by_
break;
}
}
- up(&nodemgr_ne_class.sem);
+ mutex_unlock(&nodemgr_ne_class.mutex);

return ret_ne;
}
@@ -909,7 +909,7 @@ static struct node_entry *find_entry_by_
struct device *dev;
struct node_entry *ne, *ret_ne = NULL;

- down(&nodemgr_ne_class.sem);
+ mutex_lock(&nodemgr_ne_class.mutex);
list_for_each_entry(dev, &nodemgr_ne_class.devices, node) {
ne = container_of(dev, struct node_entry, node_dev);

@@ -918,7 +918,7 @@ static struct node_entry *find_entry_by_
break;
}
}
- up(&nodemgr_ne_class.sem);
+ mutex_unlock(&nodemgr_ne_class.mutex);

return ret_ne;
}
@@ -1384,7 +1384,7 @@ static void nodemgr_suspend_ne(struct no
ne->in_limbo = 1;
WARN_ON(device_create_file(&ne->device, &dev_attr_ne_in_limbo));

- down(&nodemgr_ud_class.sem);
+ mutex_lock(&nodemgr_ud_class.mutex);
list_for_each_entry(dev, &nodemgr_ud_class.devices, node) {
ud = container_of(dev, struct unit_directory, unit_dev);
if (ud->ne != ne)
@@ -1404,7 +1404,7 @@ static void nodemgr_suspend_ne(struct no
device_release_driver(&ud->device);
put_driver(drv);
}
- up(&nodemgr_ud_class.sem);
+ mutex_unlock(&nodemgr_ud_class.mutex);
}


@@ -1417,7 +1417,7 @@ static void nodemgr_resume_ne(struct nod
ne->in_limbo = 0;
device_remove_file(&ne->device, &dev_attr_ne_in_limbo);

- down(&nodemgr_ud_class.sem);
+ mutex_lock(&nodemgr_ud_class.mutex);
list_for_each_entry(dev, &nodemgr_ud_class.devices, node) {
ud = container_of(dev, struct unit_directory, unit_dev);
if (ud->ne != ne)
@@ -1434,7 +1434,7 @@ static void nodemgr_resume_ne(struct nod
}
put_driver(drv);
}
- up(&nodemgr_ud_class.sem);
+ mutex_unlock(&nodemgr_ud_class.mutex);

HPSB_DEBUG("Node resumed: ID:BUS[" NODE_BUS_FMT "] GUID[%016Lx]",
NODE_BUS_ARGS(ne->host, ne->nodeid), (unsigned long long)ne->guid);
@@ -1449,7 +1449,7 @@ static void nodemgr_update_pdrv(struct n
struct hpsb_protocol_driver *pdrv;
int error;

- down(&nodemgr_ud_class.sem);
+ mutex_lock(&nodemgr_ud_class.mutex);
list_for_each_entry(dev, &nodemgr_ud_class.devices, node) {
ud = container_of(dev, struct unit_directory, unit_dev);
if (ud->ne != ne)
@@ -1470,7 +1470,7 @@ static void nodemgr_update_pdrv(struct n
device_release_driver(&ud->device);
put_driver(drv);
}
- up(&nodemgr_ud_class.sem);
+ mutex_unlock(&nodemgr_ud_class.mutex);
}


@@ -1545,7 +1545,7 @@ static void nodemgr_node_probe(struct ho
* while probes are time-consuming. (Well, those probes need some
* improvement...) */

- down(&nodemgr_ne_class.sem);
+ mutex_lock(&nodemgr_ne_class.mutex);
list_for_each_entry(dev, &nodemgr_ne_class.devices, node) {
ne = container_of(dev, struct node_entry, node_dev);
if (!ne->needs_probe)
@@ -1556,7 +1556,7 @@ static void nodemgr_node_probe(struct ho
if (ne->needs_probe)
nodemgr_probe_ne(hi, ne, generation);
}
- up(&nodemgr_ne_class.sem);
+ mutex_unlock(&nodemgr_ne_class.mutex);


/* If we had a bus reset while we were scanning the bus, it is
@@ -1775,14 +1775,14 @@ int nodemgr_for_each_host(void *data, in
struct hpsb_host *host;
int error = 0;

- down(&hpsb_host_class.sem);
+ mutex_lock(&hpsb_host_class.mutex);
list_for_each_entry(dev, &hpsb_host_class.devices, node) {
host = container_of(dev, struct hpsb_host, host_dev);

if ((error = cb(host, data)))
break;
}
- up(&hpsb_host_class.sem);
+ mutex_unlock(&hpsb_host_class.mutex);

return error;
}
diff -upr a/linux-2.6.24-rc7/drivers/power/apm_power.c linux-2.6.24-rc7/drivers/power/apm_power.c
--- a/linux-2.6.24-rc7/drivers/power/apm_power.c 2008-01-07 08:56:08.000000000 +0800
+++ linux-2.6.24-rc7/drivers/power/apm_power.c 2008-01-07 09:27:05.000000000 +0800
@@ -207,10 +207,10 @@ static void apm_battery_apm_get_power_st
union power_supply_propval status;
union power_supply_propval capacity, time_to_full, time_to_empty;

- down(&power_supply_class->sem);
+ mutex_lock(&power_supply_class->mutex);
find_main_battery();
if (!main_battery) {
- up(&power_supply_class->sem);
+ mutex_unlock(&power_supply_class->mutex);
return;
}

@@ -278,7 +278,7 @@ static void apm_battery_apm_get_power_st
}
}

- up(&power_supply_class->sem);
+ mutex_unlock(&power_supply_class->mutex);
}

static int __init apm_battery_init(void)
diff -upr a/linux-2.6.24-rc7/drivers/power/power_supply_core.c linux-2.6.24-rc7/drivers/power/power_supply_core.c
--- a/linux-2.6.24-rc7/drivers/power/power_supply_core.c 2007-10-10 04:31:38.000000000 +0800
+++ linux-2.6.24-rc7/drivers/power/power_supply_core.c 2008-01-07 09:27:05.000000000 +0800
@@ -31,7 +31,7 @@ static void power_supply_changed_work(st
for (i = 0; i < psy->num_supplicants; i++) {
struct device *dev;

- down(&power_supply_class->sem);
+ mutex_lock(&power_supply_class->mutex);
list_for_each_entry(dev, &power_supply_class->devices, node) {
struct power_supply *pst = dev_get_drvdata(dev);

@@ -40,7 +40,7 @@ static void power_supply_changed_work(st
pst->external_power_changed(pst);
}
}
- up(&power_supply_class->sem);
+ mutex_unlock(&power_supply_class->mutex);
}

power_supply_update_leds(psy);
@@ -60,7 +60,7 @@ int power_supply_am_i_supplied(struct po
union power_supply_propval ret = {0,};
struct device *dev;

- down(&power_supply_class->sem);
+ mutex_lock(&power_supply_class->mutex);
list_for_each_entry(dev, &power_supply_class->devices, node) {
struct power_supply *epsy = dev_get_drvdata(dev);
int i;
@@ -76,7 +76,7 @@ int power_supply_am_i_supplied(struct po
}
}
out:
- up(&power_supply_class->sem);
+ mutex_unlock(&power_supply_class->mutex);

dev_dbg(psy->dev, "%s %d\n", __FUNCTION__, ret.intval);

diff -upr a/linux-2.6.24-rc7/drivers/rtc/interface.c linux-2.6.24-rc7/drivers/rtc/interface.c
--- a/linux-2.6.24-rc7/drivers/rtc/interface.c 2008-01-07 08:56:08.000000000 +0800
+++ linux-2.6.24-rc7/drivers/rtc/interface.c 2008-01-07 09:27:11.000000000 +0800
@@ -256,7 +256,7 @@ struct rtc_device *rtc_class_open(char *
struct device *dev;
struct rtc_device *rtc = NULL;

- down(&rtc_class->sem);
+ mutex_lock(&rtc_class->mutex);
list_for_each_entry(dev, &rtc_class->devices, node) {
if (strncmp(dev->bus_id, name, BUS_ID_SIZE) == 0) {
dev = get_device(dev);
@@ -272,7 +272,7 @@ struct rtc_device *rtc_class_open(char *
rtc = NULL;
}
}
- up(&rtc_class->sem);
+ mutex_unlock(&rtc_class->mutex);

return rtc;
}
diff -upr a/linux-2.6.24-rc7/drivers/scsi/hosts.c linux-2.6.24-rc7/drivers/scsi/hosts.c
--- a/linux-2.6.24-rc7/drivers/scsi/hosts.c 2008-01-07 08:56:09.000000000 +0800
+++ linux-2.6.24-rc7/drivers/scsi/hosts.c 2008-01-07 09:25:42.000000000 +0800
@@ -443,7 +443,7 @@ struct Scsi_Host *scsi_host_lookup(unsig
struct class_device *cdev;
struct Scsi_Host *shost = ERR_PTR(-ENXIO), *p;

- down(&class->sem);
+ mutex_lock(&class->mutex);
list_for_each_entry(cdev, &class->children, node) {
p = class_to_shost(cdev);
if (p->host_no == hostnum) {
@@ -451,7 +451,7 @@ struct Scsi_Host *scsi_host_lookup(unsig
break;
}
}
- up(&class->sem);
+ mutex_unlock(&class->mutex);

return shost;
}
diff -upr a/linux-2.6.24-rc7/drivers/spi/spi.c linux-2.6.24-rc7/drivers/spi/spi.c
--- a/linux-2.6.24-rc7/drivers/spi/spi.c 2008-01-07 08:56:09.000000000 +0800
+++ linux-2.6.24-rc7/drivers/spi/spi.c 2008-01-07 09:26:30.000000000 +0800
@@ -501,7 +501,7 @@ struct spi_master *spi_busnum_to_master(
struct spi_master *master = NULL;
struct spi_master *m;

- down(&spi_master_class.sem);
+ mutex_lock(&spi_master_class.mutex);
list_for_each_entry(dev, &spi_master_class.children, node) {
m = container_of(dev, struct spi_master, dev);
if (m->bus_num == bus_num) {
@@ -509,7 +509,7 @@ struct spi_master *spi_busnum_to_master(
break;
}
}
- up(&spi_master_class.sem);
+ mutex_unlock(&spi_master_class.mutex);
return master;
}
EXPORT_SYMBOL_GPL(spi_busnum_to_master);
diff -upr a/linux-2.6.24-rc7/include/linux/device.h linux-2.6.24-rc7/include/linux/device.h
--- a/linux-2.6.24-rc7/include/linux/device.h 2008-01-07 08:56:11.000000000 +0800
+++ linux-2.6.24-rc7/include/linux/device.h 2008-01-07 09:19:29.000000000 +0800
@@ -20,6 +20,7 @@
#include <linux/types.h>
#include <linux/module.h>
#include <linux/pm.h>
+#include <linux/mutex.h>
#include <asm/semaphore.h>
#include <asm/atomic.h>
#include <asm/device.h>
@@ -180,7 +181,7 @@ struct class {
struct list_head devices;
struct list_head interfaces;
struct kset class_dirs;
- struct semaphore sem; /* locks both the children and interfaces lists */
+ struct mutex mutex; /* locks both the children and interfaces lists */

struct class_attribute * class_attrs;
struct class_device_attribute * class_dev_attrs;

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