[RFC PATCH v3 04/17] vbus: add bus-registration notifiers

Gregory Haskins
2009-04-21T18:36:48Z

We need to get hotswap events in environments which cannot use existing
facilities (e.g. inotify). So we add a notifier-chain to allow client
callbacks whenever an interface is {un}registered.

Signed-off-by: Gregory Haskins <ghaskins@novell.com>
---

include/linux/vbus.h | 15 +++++++++++++
kernel/vbus/core.c | 59 ++++++++++++++++++++++++++++++++++++++++++++++++++
kernel/vbus/vbus.h | 1 +
3 files changed, 75 insertions(+), 0 deletions(-)

diff --git a/include/linux/vbus.h b/include/linux/vbus.h
index 5f0566c..04db4ff 100644
--- a/include/linux/vbus.h
+++ b/include/linux/vbus.h
@@ -29,6 +29,7 @@
#include <linux/sched.h>
#include <linux/rcupdate.h>
#include <linux/vbus_device.h>
+#include <linux/notifier.h>

struct vbus;
struct task_struct;
@@ -137,6 +138,20 @@ static inline void task_vbus_disassociate(struct task_struct *p)
}
}

+enum {
+ VBUS_EVENT_DEVADD,
+ VBUS_EVENT_DEVDROP,
+};
+
+struct vbus_event_devadd {
+ const char *type;
+ unsigned long id;
+};
+
+int vbus_notifier_register(struct vbus *vbus, struct notifier_block *nb);
+int vbus_notifier_unregister(struct vbus *vbus, struct notifier_block *nb);
+
+
#else /* CONFIG_VBUS */

#define fork_vbus(p) do { } while (0)
diff --git a/kernel/vbus/core.c b/kernel/vbus/core.c
index 033999f..b6df487 100644
--- a/kernel/vbus/core.c
+++ b/kernel/vbus/core.c
@@ -89,6 +89,7 @@ int vbus_device_interface_register(struct vbus_device *dev,
{
int ret;
struct vbus_devshell *ds = to_devshell(dev->kobj);
+ struct vbus_event_devadd ev;

mutex_lock(&vbus->lock);

@@ -124,6 +125,14 @@ int vbus_device_interface_register(struct vbus_device *dev,
if (ret)
goto error;

+ ev.type = intf->type;
+ ev.id = intf->id;
+
+ /* and let any clients know about the new device */
+ ret = raw_notifier_call_chain(&vbus->notifier, VBUS_EVENT_DEVADD, &ev);
+ if (ret < 0)
+ goto error;
+
mutex_unlock(&vbus->lock);

return 0;
@@ -144,6 +153,7 @@ int vbus_device_interface_unregister(struct vbus_device_interface *intf)

mutex_lock(&vbus->lock);
_interface_unregister(intf);
+ raw_notifier_call_chain(&vbus->notifier, VBUS_EVENT_DEVDROP, &intf->id);
mutex_unlock(&vbus->lock);

kobject_put(&intf->kobj);
@@ -346,6 +356,8 @@ int vbus_create(const char *name, struct vbus **bus)

_bus->next_id = 0;

+ RAW_INIT_NOTIFIER_HEAD(&_bus->notifier);
+
mutex_lock(&vbus_root.lock);

ret = map_add(&vbus_root.buses.map, &_bus->node);
@@ -358,6 +370,53 @@ int vbus_create(const char *name, struct vbus **bus)
return 0;
}

+#define for_each_rbnode(node, root) \
+ for (node = rb_first(root); node != NULL; node = rb_next(node))
+
+int vbus_notifier_register(struct vbus *vbus, struct notifier_block *nb)
+{
+ int ret;
+ struct rb_node *node;
+
+ mutex_lock(&vbus->lock);
+
+ /*
+ * resync the client for any devices we might already have
+ */
+ for_each_rbnode(node, &vbus->devices.map.root) {
+ struct vbus_device_interface *intf = node_to_intf(node);
+ struct vbus_event_devadd ev = {
+ .type = intf->type,
+ .id = intf->id,
+ };
+
+ ret = nb->notifier_call(nb, VBUS_EVENT_DEVADD, &ev);
+ if (ret & NOTIFY_STOP_MASK) {
+ mutex_unlock(&vbus->lock);
+ return -EPERM;
+ }
+ }
+
+ ret = raw_notifier_chain_register(&vbus->notifier, nb);
+
+ mutex_unlock(&vbus->lock);
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(vbus_notifier_register);
+
+int vbus_notifier_unregister(struct vbus *vbus, struct notifier_block *nb)
+{
+ int ret;
+
+ mutex_lock(&vbus->lock);
+ ret = raw_notifier_chain_unregister(&vbus->notifier, nb);
+ mutex_unlock(&vbus->lock);
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(vbus_notifier_unregister);
+
static void devshell_release(struct kobject *kobj)
{
struct vbus_devshell *ds = container_of(kobj,
diff --git a/kernel/vbus/vbus.h b/kernel/vbus/vbus.h
index 1266d69..cd2676b 100644
--- a/kernel/vbus/vbus.h
+++ b/kernel/vbus/vbus.h
@@ -51,6 +51,7 @@ struct vbus {
struct vbus_subdir members;
unsigned long next_id;
struct rb_node node;
+ struct raw_notifier_head notifier;
};

struct vbus_member {