[PATCH] Add a klist to struct bus_type for its devices.

- Use it for bus_for_each_dev().
- Use the klist spinlock instead of the bus rwsem.

Signed-off-by: Patrick Mochel <mochel@digitalimplant.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

2 files changed, 27 insertions, 30 deletions

diff --git a/drivers/base/bus.c b/drivers/base/bus.c
index 1b05c1399e37..c8da37230b3e 100644
--- a/drivers/base/bus.c
+++ b/drivers/base/bus.c
@@ -134,28 +134,6 @@ static struct kobj_type ktype_bus = {
 
 decl_subsys(bus, &ktype_bus, NULL);
 
-static int __bus_for_each_dev(struct bus_type *bus, struct device *start,
-                              void *data, int (*fn)(struct device *, void *))
-{
-        struct list_head *head;
-        struct device *dev;
-        int error = 0;
-
-        if (!(bus = get_bus(bus)))
-                return -EINVAL;
-
-        head = &bus->devices.list;
-        dev = list_prepare_entry(start, head, bus_list);
-        list_for_each_entry_continue(dev, head, bus_list) {
-                get_device(dev);
-                error = fn(dev, data);
-                put_device(dev);
-                if (error)
-                        break;
-        }
-        put_bus(bus);
-        return error;
-}
 
 static int __bus_for_each_drv(struct bus_type *bus, struct device_driver *start,
                               void * data, int (*fn)(struct device_driver *, void *))
@@ -180,6 +158,13 @@ static int __bus_for_each_drv(struct bus_type *bus, struct device_driver *start,
         return error;
 }
 
+
+static struct device * next_device(struct klist_iter * i)
+{
+        struct klist_node * n = klist_next(i);
+        return n ? container_of(n, struct device, knode_bus) : NULL;
+}
+
 /**
  *      bus_for_each_dev - device iterator.
  *      @bus:   bus type.
@@ -203,12 +188,19 @@ static int __bus_for_each_drv(struct bus_type *bus, struct device_driver *start,
 int bus_for_each_dev(struct bus_type * bus, struct device * start,
                      void * data, int (*fn)(struct device *, void *))
 {
-        int ret;
+        struct klist_iter i;
+        struct device * dev;
+        int error = 0;
 
-        down_read(&bus->subsys.rwsem);
-        ret = __bus_for_each_dev(bus, start, data, fn);
-        up_read(&bus->subsys.rwsem);
-        return ret;
+        if (!bus)
+                return -EINVAL;
+
+        klist_iter_init_node(&bus->klist_devices, &i,
+                             (start ? &start->knode_bus : NULL));
+        while ((dev = next_device(&i)) && !error)
+                error = fn(dev, data);
+        klist_iter_exit(&i);
+        return error;
 }
 
 /**
@@ -293,6 +285,7 @@ int bus_add_device(struct device * dev)
                 list_add_tail(&dev->bus_list, &dev->bus->devices.list);
                 device_attach(dev);
                 up_write(&dev->bus->subsys.rwsem);
+                klist_add_tail(&bus->klist_devices, &dev->knode_bus);
                 device_add_attrs(bus, dev);
                 sysfs_create_link(&bus->devices.kobj, &dev->kobj, dev->bus_id);
                 sysfs_create_link(&dev->kobj, &dev->bus->subsys.kset.kobj, "bus");
@@ -315,6 +308,7 @@ void bus_remove_device(struct device * dev)
                 sysfs_remove_link(&dev->kobj, "bus");
                 sysfs_remove_link(&dev->bus->devices.kobj, dev->bus_id);
                 device_remove_attrs(dev->bus, dev);
+                klist_remove(&dev->knode_bus);
                 down_write(&dev->bus->subsys.rwsem);
                 pr_debug("bus %s: remove device %s\n", dev->bus->name, dev->bus_id);
                 device_release_driver(dev);
@@ -439,9 +433,7 @@ int bus_rescan_devices(struct bus_type * bus)
 {
         int count = 0;
 
-        down_write(&bus->subsys.rwsem);
-        __bus_for_each_dev(bus, NULL, &count, bus_rescan_devices_helper);
-        up_write(&bus->subsys.rwsem);
+        bus_for_each_dev(bus, NULL, &count, bus_rescan_devices_helper);
 
         return count;
 }
@@ -542,6 +534,8 @@ int bus_register(struct bus_type * bus)
         retval = kset_register(&bus->drivers);
         if (retval)
                 goto bus_drivers_fail;
+
+        klist_init(&bus->klist_devices);
         bus_add_attrs(bus);
 
         pr_debug("bus type '%s' registered\n", bus->name);
diff --git a/include/linux/device.h b/include/linux/device.h
index 10f5aa20e041..e36953cf7f14 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -14,6 +14,7 @@
 #include <linux/config.h>
 #include <linux/ioport.h>
 #include <linux/kobject.h>
+#include <linux/klist.h>
 #include <linux/list.h>
 #include <linux/types.h>
 #include <linux/module.h>
@@ -51,6 +52,7 @@ struct bus_type {
         struct subsystem        subsys;
         struct kset             drivers;
         struct kset             devices;
+        struct klist            klist_devices;
 
         struct bus_attribute    * bus_attrs;
         struct device_attribute * dev_attrs;
@@ -262,6 +264,7 @@ struct device {
         struct list_head bus_list;      /* node in bus's list */
         struct list_head driver_list;
         struct list_head children;
+        struct klist_node       knode_bus;
         struct device   * parent;
 
         struct kobject kobj;