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1/*
2 * Routines to manage notifier chains for passing status changes to any
3 * interested routines. We need this instead of hard coded call lists so
4 * that modules can poke their nose into the innards. The network devices
5 * needed them so here they are for the rest of you.
6 *
7 * Alan Cox <Alan.Cox@linux.org>
8 */
9
10#ifndef _LINUX_NOTIFIER_H
11#define _LINUX_NOTIFIER_H
12#include <linux/errno.h>
13#include <linux/mutex.h>
14#include <linux/rwsem.h>
15
16/*
17 * Notifier chains are of three types:
18 *
19 * Atomic notifier chains: Chain callbacks run in interrupt/atomic
20 * context. Callouts are not allowed to block.
21 * Blocking notifier chains: Chain callbacks run in process context.
22 * Callouts are allowed to block.
23 * Raw notifier chains: There are no restrictions on callbacks,
24 * registration, or unregistration. All locking and protection
25 * must be provided by the caller.
26 *
27 * atomic_notifier_chain_register() may be called from an atomic context,
28 * but blocking_notifier_chain_register() must be called from a process
29 * context. Ditto for the corresponding _unregister() routines.
30 *
31 * atomic_notifier_chain_unregister() and blocking_notifier_chain_unregister()
32 * _must not_ be called from within the call chain.
33 */
34
35struct notifier_block {
36 int (*notifier_call)(struct notifier_block *, unsigned long, void *);
37 struct notifier_block *next;
38 int priority;
39};
40
41struct atomic_notifier_head {
42 spinlock_t lock;
43 struct notifier_block *head;
44};
45
46struct blocking_notifier_head {
47 struct rw_semaphore rwsem;
48 struct notifier_block *head;
49};
50
51struct raw_notifier_head {
52 struct notifier_block *head;
53};
54
55#define ATOMIC_INIT_NOTIFIER_HEAD(name) do { \
56 spin_lock_init(&(name)->lock); \
57 (name)->head = NULL; \
58 } while (0)
59#define BLOCKING_INIT_NOTIFIER_HEAD(name) do { \
60 init_rwsem(&(name)->rwsem); \
61 (name)->head = NULL; \
62 } while (0)
63#define RAW_INIT_NOTIFIER_HEAD(name) do { \
64 (name)->head = NULL; \
65 } while (0)
66
67#define ATOMIC_NOTIFIER_INIT(name) { \
68 .lock = SPIN_LOCK_UNLOCKED, \
69 .head = NULL }
70#define BLOCKING_NOTIFIER_INIT(name) { \
71 .rwsem = __RWSEM_INITIALIZER((name).rwsem), \
72 .head = NULL }
73#define RAW_NOTIFIER_INIT(name) { \
74 .head = NULL }
75
76#define ATOMIC_NOTIFIER_HEAD(name) \
77 struct atomic_notifier_head name = \
78 ATOMIC_NOTIFIER_INIT(name)
79#define BLOCKING_NOTIFIER_HEAD(name) \
80 struct blocking_notifier_head name = \
81 BLOCKING_NOTIFIER_INIT(name)
82#define RAW_NOTIFIER_HEAD(name) \
83 struct raw_notifier_head name = \
84 RAW_NOTIFIER_INIT(name)
85
86#ifdef __KERNEL__
87
88extern int atomic_notifier_chain_register(struct atomic_notifier_head *,
89 struct notifier_block *);
90extern int blocking_notifier_chain_register(struct blocking_notifier_head *,
91 struct notifier_block *);
92extern int raw_notifier_chain_register(struct raw_notifier_head *,
93 struct notifier_block *);
94
95extern int atomic_notifier_chain_unregister(struct atomic_notifier_head *,
96 struct notifier_block *);
97extern int blocking_notifier_chain_unregister(struct blocking_notifier_head *,
98 struct notifier_block *);
99extern int raw_notifier_chain_unregister(struct raw_notifier_head *,
100 struct notifier_block *);
101
102extern int atomic_notifier_call_chain(struct atomic_notifier_head *,
103 unsigned long val, void *v);
104extern int blocking_notifier_call_chain(struct blocking_notifier_head *,
105 unsigned long val, void *v);
106extern int raw_notifier_call_chain(struct raw_notifier_head *,
107 unsigned long val, void *v);
108
109#define NOTIFY_DONE 0x0000 /* Don't care */
110#define NOTIFY_OK 0x0001 /* Suits me */
111#define NOTIFY_STOP_MASK 0x8000 /* Don't call further */
112#define NOTIFY_BAD (NOTIFY_STOP_MASK|0x0002)
113 /* Bad/Veto action */
114/*
115 * Clean way to return from the notifier and stop further calls.
116 */
117#define NOTIFY_STOP (NOTIFY_OK|NOTIFY_STOP_MASK)
118
119/*
120 * Declared notifiers so far. I can imagine quite a few more chains
121 * over time (eg laptop power reset chains, reboot chain (to clean
122 * device units up), device [un]mount chain, module load/unload chain,
123 * low memory chain, screenblank chain (for plug in modular screenblankers)
124 * VC switch chains (for loadable kernel svgalib VC switch helpers) etc...
125 */
126
127/* netdevice notifier chain */
128#define NETDEV_UP 0x0001 /* For now you can't veto a device up/down */
129#define NETDEV_DOWN 0x0002
130#define NETDEV_REBOOT 0x0003 /* Tell a protocol stack a network interface
131 detected a hardware crash and restarted
132 - we can use this eg to kick tcp sessions
133 once done */
134#define NETDEV_CHANGE 0x0004 /* Notify device state change */
135#define NETDEV_REGISTER 0x0005
136#define NETDEV_UNREGISTER 0x0006
137#define NETDEV_CHANGEMTU 0x0007
138#define NETDEV_CHANGEADDR 0x0008
139#define NETDEV_GOING_DOWN 0x0009
140#define NETDEV_CHANGENAME 0x000A
141#define NETDEV_FEAT_CHANGE 0x000B
142
143#define SYS_DOWN 0x0001 /* Notify of system down */
144#define SYS_RESTART SYS_DOWN
145#define SYS_HALT 0x0002 /* Notify of system halt */
146#define SYS_POWER_OFF 0x0003 /* Notify of system power off */
147
148#define NETLINK_URELEASE 0x0001 /* Unicast netlink socket released */
149
150#define CPU_ONLINE 0x0002 /* CPU (unsigned)v is up */
151#define CPU_UP_PREPARE 0x0003 /* CPU (unsigned)v coming up */
152#define CPU_UP_CANCELED 0x0004 /* CPU (unsigned)v NOT coming up */
153#define CPU_DOWN_PREPARE 0x0005 /* CPU (unsigned)v going down */
154#define CPU_DOWN_FAILED 0x0006 /* CPU (unsigned)v NOT going down */
155#define CPU_DEAD 0x0007 /* CPU (unsigned)v dead */
156
157#endif /* __KERNEL__ */
158#endif /* _LINUX_NOTIFIER_H */