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

- Use it in bus_for_each_drv().
- 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, 25 insertions, 29 deletions

diff --git a/drivers/base/bus.c b/drivers/base/bus.c
index c8da37230b3e..736dc1f5a316 100644
--- a/drivers/base/bus.c
+++ b/drivers/base/bus.c
@@ -135,30 +135,6 @@ static struct kobj_type ktype_bus = {
 decl_subsys(bus, &ktype_bus, NULL);
 
 
-static int __bus_for_each_drv(struct bus_type *bus, struct device_driver *start,
-                              void * data, int (*fn)(struct device_driver *, void *))
-{
-        struct list_head *head;
-        struct device_driver *drv;
-        int error = 0;
-
-        if (!(bus = get_bus(bus)))
-                return -EINVAL;
-
-        head = &bus->drivers.list;
-        drv = list_prepare_entry(start, head, kobj.entry);
-        list_for_each_entry_continue(drv, head, kobj.entry) {
-                get_driver(drv);
-                error = fn(drv, data);
-                put_driver(drv);
-                if (error)
-                        break;
-        }
-        put_bus(bus);
-        return error;
-}
-
-
 static struct device * next_device(struct klist_iter * i)
 {
         struct klist_node * n = klist_next(i);
@@ -203,6 +179,14 @@ int bus_for_each_dev(struct bus_type * bus, struct device * start,
         return error;
 }
 
+
+
+static struct device_driver * next_driver(struct klist_iter * i)
+{
+        struct klist_node * n = klist_next(i);
+        return n ? container_of(n, struct device_driver, knode_bus) : NULL;
+}
+
 /**
  *      bus_for_each_drv - driver iterator
  *      @bus:   bus we're dealing with.
@@ -226,12 +210,19 @@ int bus_for_each_dev(struct bus_type * bus, struct device * start,
 int bus_for_each_drv(struct bus_type * bus, struct device_driver * start,
                      void * data, int (*fn)(struct device_driver *, void *))
 {
-        int ret;
+        struct klist_iter i;
+        struct device_driver * drv;
+        int error = 0;
 
-        down_read(&bus->subsys.rwsem);
-        ret = __bus_for_each_drv(bus, start, data, fn);
-        up_read(&bus->subsys.rwsem);
-        return ret;
+        if (!bus)
+                return -EINVAL;
+
+        klist_iter_init_node(&bus->klist_drivers, &i,
+                             start ? &start->knode_bus : NULL);
+        while ((drv = next_driver(&i)) && !error)
+                error = fn(drv, data);
+        klist_iter_exit(&i);
+        return error;
 }
 
 static int device_add_attrs(struct bus_type * bus, struct device * dev)
@@ -376,6 +367,7 @@ int bus_add_driver(struct device_driver * drv)
                 down_write(&bus->subsys.rwsem);
                 driver_attach(drv);
                 up_write(&bus->subsys.rwsem);
+                klist_add_tail(&bus->klist_drivers, &drv->knode_bus);
                 module_add_driver(drv->owner, drv);
 
                 driver_add_attrs(bus, drv);
@@ -397,6 +389,7 @@ void bus_remove_driver(struct device_driver * drv)
 {
         if (drv->bus) {
                 driver_remove_attrs(drv->bus, drv);
+                klist_remove(&drv->knode_bus);
                 down_write(&drv->bus->subsys.rwsem);
                 pr_debug("bus %s: remove driver %s\n", drv->bus->name, drv->name);
                 driver_detach(drv);
@@ -536,6 +529,7 @@ int bus_register(struct bus_type * bus)
                 goto bus_drivers_fail;
 
         klist_init(&bus->klist_devices);
+        klist_init(&bus->klist_drivers);
         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 e36953cf7f14..ea9ab33dfe71 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -53,6 +53,7 @@ struct bus_type {
         struct kset             drivers;
         struct kset             devices;
         struct klist            klist_devices;
+        struct klist            klist_drivers;
 
         struct bus_attribute    * bus_attrs;
         struct device_attribute * dev_attrs;
@@ -105,6 +106,7 @@ struct device_driver {
         struct completion       unloaded;
         struct kobject          kobj;
         struct list_head        devices;
+        struct klist_node       knode_bus;
 
         struct module           * owner;