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1da177e4 LT |
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> | |
e041c683 AS |
13 | #include <linux/mutex.h> |
14 | #include <linux/rwsem.h> | |
eabc0694 | 15 | #include <linux/srcu.h> |
1da177e4 | 16 | |
e041c683 | 17 | /* |
eabc0694 | 18 | * Notifier chains are of four types: |
e041c683 AS |
19 | * |
20 | * Atomic notifier chains: Chain callbacks run in interrupt/atomic | |
21 | * context. Callouts are not allowed to block. | |
22 | * Blocking notifier chains: Chain callbacks run in process context. | |
23 | * Callouts are allowed to block. | |
24 | * Raw notifier chains: There are no restrictions on callbacks, | |
25 | * registration, or unregistration. All locking and protection | |
26 | * must be provided by the caller. | |
eabc0694 AS |
27 | * SRCU notifier chains: A variant of blocking notifier chains, with |
28 | * the same restrictions. | |
e041c683 AS |
29 | * |
30 | * atomic_notifier_chain_register() may be called from an atomic context, | |
eabc0694 AS |
31 | * but blocking_notifier_chain_register() and srcu_notifier_chain_register() |
32 | * must be called from a process context. Ditto for the corresponding | |
33 | * _unregister() routines. | |
e041c683 | 34 | * |
eabc0694 AS |
35 | * atomic_notifier_chain_unregister(), blocking_notifier_chain_unregister(), |
36 | * and srcu_notifier_chain_unregister() _must not_ be called from within | |
37 | * the call chain. | |
38 | * | |
39 | * SRCU notifier chains are an alternative form of blocking notifier chains. | |
40 | * They use SRCU (Sleepable Read-Copy Update) instead of rw-semaphores for | |
41 | * protection of the chain links. This means there is _very_ low overhead | |
42 | * in srcu_notifier_call_chain(): no cache bounces and no memory barriers. | |
43 | * As compensation, srcu_notifier_chain_unregister() is rather expensive. | |
44 | * SRCU notifier chains should be used when the chain will be called very | |
45 | * often but notifier_blocks will seldom be removed. Also, SRCU notifier | |
46 | * chains are slightly more difficult to use because they require special | |
47 | * runtime initialization. | |
e041c683 AS |
48 | */ |
49 | ||
50 | struct notifier_block { | |
51 | int (*notifier_call)(struct notifier_block *, unsigned long, void *); | |
1da177e4 LT |
52 | struct notifier_block *next; |
53 | int priority; | |
54 | }; | |
55 | ||
e041c683 AS |
56 | struct atomic_notifier_head { |
57 | spinlock_t lock; | |
58 | struct notifier_block *head; | |
59 | }; | |
60 | ||
61 | struct blocking_notifier_head { | |
62 | struct rw_semaphore rwsem; | |
63 | struct notifier_block *head; | |
64 | }; | |
65 | ||
66 | struct raw_notifier_head { | |
67 | struct notifier_block *head; | |
68 | }; | |
69 | ||
eabc0694 AS |
70 | struct srcu_notifier_head { |
71 | struct mutex mutex; | |
72 | struct srcu_struct srcu; | |
73 | struct notifier_block *head; | |
74 | }; | |
75 | ||
e041c683 AS |
76 | #define ATOMIC_INIT_NOTIFIER_HEAD(name) do { \ |
77 | spin_lock_init(&(name)->lock); \ | |
78 | (name)->head = NULL; \ | |
79 | } while (0) | |
80 | #define BLOCKING_INIT_NOTIFIER_HEAD(name) do { \ | |
81 | init_rwsem(&(name)->rwsem); \ | |
82 | (name)->head = NULL; \ | |
83 | } while (0) | |
84 | #define RAW_INIT_NOTIFIER_HEAD(name) do { \ | |
85 | (name)->head = NULL; \ | |
86 | } while (0) | |
87 | ||
eabc0694 AS |
88 | /* srcu_notifier_heads must be initialized and cleaned up dynamically */ |
89 | extern void srcu_init_notifier_head(struct srcu_notifier_head *nh); | |
90 | #define srcu_cleanup_notifier_head(name) \ | |
91 | cleanup_srcu_struct(&(name)->srcu); | |
92 | ||
e041c683 | 93 | #define ATOMIC_NOTIFIER_INIT(name) { \ |
e4d91918 | 94 | .lock = __SPIN_LOCK_UNLOCKED(name.lock), \ |
e041c683 AS |
95 | .head = NULL } |
96 | #define BLOCKING_NOTIFIER_INIT(name) { \ | |
97 | .rwsem = __RWSEM_INITIALIZER((name).rwsem), \ | |
98 | .head = NULL } | |
99 | #define RAW_NOTIFIER_INIT(name) { \ | |
100 | .head = NULL } | |
eabc0694 | 101 | /* srcu_notifier_heads cannot be initialized statically */ |
e041c683 AS |
102 | |
103 | #define ATOMIC_NOTIFIER_HEAD(name) \ | |
104 | struct atomic_notifier_head name = \ | |
105 | ATOMIC_NOTIFIER_INIT(name) | |
106 | #define BLOCKING_NOTIFIER_HEAD(name) \ | |
107 | struct blocking_notifier_head name = \ | |
108 | BLOCKING_NOTIFIER_INIT(name) | |
109 | #define RAW_NOTIFIER_HEAD(name) \ | |
110 | struct raw_notifier_head name = \ | |
111 | RAW_NOTIFIER_INIT(name) | |
1da177e4 LT |
112 | |
113 | #ifdef __KERNEL__ | |
114 | ||
e041c683 AS |
115 | extern int atomic_notifier_chain_register(struct atomic_notifier_head *, |
116 | struct notifier_block *); | |
117 | extern int blocking_notifier_chain_register(struct blocking_notifier_head *, | |
118 | struct notifier_block *); | |
119 | extern int raw_notifier_chain_register(struct raw_notifier_head *, | |
120 | struct notifier_block *); | |
eabc0694 AS |
121 | extern int srcu_notifier_chain_register(struct srcu_notifier_head *, |
122 | struct notifier_block *); | |
e041c683 AS |
123 | |
124 | extern int atomic_notifier_chain_unregister(struct atomic_notifier_head *, | |
125 | struct notifier_block *); | |
126 | extern int blocking_notifier_chain_unregister(struct blocking_notifier_head *, | |
127 | struct notifier_block *); | |
128 | extern int raw_notifier_chain_unregister(struct raw_notifier_head *, | |
129 | struct notifier_block *); | |
eabc0694 AS |
130 | extern int srcu_notifier_chain_unregister(struct srcu_notifier_head *, |
131 | struct notifier_block *); | |
e041c683 AS |
132 | |
133 | extern int atomic_notifier_call_chain(struct atomic_notifier_head *, | |
134 | unsigned long val, void *v); | |
135 | extern int blocking_notifier_call_chain(struct blocking_notifier_head *, | |
136 | unsigned long val, void *v); | |
137 | extern int raw_notifier_call_chain(struct raw_notifier_head *, | |
138 | unsigned long val, void *v); | |
eabc0694 AS |
139 | extern int srcu_notifier_call_chain(struct srcu_notifier_head *, |
140 | unsigned long val, void *v); | |
1da177e4 LT |
141 | |
142 | #define NOTIFY_DONE 0x0000 /* Don't care */ | |
143 | #define NOTIFY_OK 0x0001 /* Suits me */ | |
144 | #define NOTIFY_STOP_MASK 0x8000 /* Don't call further */ | |
e041c683 AS |
145 | #define NOTIFY_BAD (NOTIFY_STOP_MASK|0x0002) |
146 | /* Bad/Veto action */ | |
1da177e4 LT |
147 | /* |
148 | * Clean way to return from the notifier and stop further calls. | |
149 | */ | |
150 | #define NOTIFY_STOP (NOTIFY_OK|NOTIFY_STOP_MASK) | |
151 | ||
152 | /* | |
153 | * Declared notifiers so far. I can imagine quite a few more chains | |
154 | * over time (eg laptop power reset chains, reboot chain (to clean | |
155 | * device units up), device [un]mount chain, module load/unload chain, | |
156 | * low memory chain, screenblank chain (for plug in modular screenblankers) | |
157 | * VC switch chains (for loadable kernel svgalib VC switch helpers) etc... | |
158 | */ | |
159 | ||
160 | /* netdevice notifier chain */ | |
161 | #define NETDEV_UP 0x0001 /* For now you can't veto a device up/down */ | |
162 | #define NETDEV_DOWN 0x0002 | |
163 | #define NETDEV_REBOOT 0x0003 /* Tell a protocol stack a network interface | |
164 | detected a hardware crash and restarted | |
165 | - we can use this eg to kick tcp sessions | |
166 | once done */ | |
167 | #define NETDEV_CHANGE 0x0004 /* Notify device state change */ | |
168 | #define NETDEV_REGISTER 0x0005 | |
169 | #define NETDEV_UNREGISTER 0x0006 | |
170 | #define NETDEV_CHANGEMTU 0x0007 | |
171 | #define NETDEV_CHANGEADDR 0x0008 | |
172 | #define NETDEV_GOING_DOWN 0x0009 | |
173 | #define NETDEV_CHANGENAME 0x000A | |
d8a33ac4 | 174 | #define NETDEV_FEAT_CHANGE 0x000B |
1da177e4 LT |
175 | |
176 | #define SYS_DOWN 0x0001 /* Notify of system down */ | |
177 | #define SYS_RESTART SYS_DOWN | |
178 | #define SYS_HALT 0x0002 /* Notify of system halt */ | |
179 | #define SYS_POWER_OFF 0x0003 /* Notify of system power off */ | |
180 | ||
181 | #define NETLINK_URELEASE 0x0001 /* Unicast netlink socket released */ | |
182 | ||
183 | #define CPU_ONLINE 0x0002 /* CPU (unsigned)v is up */ | |
184 | #define CPU_UP_PREPARE 0x0003 /* CPU (unsigned)v coming up */ | |
185 | #define CPU_UP_CANCELED 0x0004 /* CPU (unsigned)v NOT coming up */ | |
186 | #define CPU_DOWN_PREPARE 0x0005 /* CPU (unsigned)v going down */ | |
187 | #define CPU_DOWN_FAILED 0x0006 /* CPU (unsigned)v NOT going down */ | |
188 | #define CPU_DEAD 0x0007 /* CPU (unsigned)v dead */ | |
189 | ||
190 | #endif /* __KERNEL__ */ | |
191 | #endif /* _LINUX_NOTIFIER_H */ |