Line data Source code
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 : #include <linux/srcu.h>
16 :
17 : /*
18 : * Notifier chains are of four types:
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.
27 : * SRCU notifier chains: A variant of blocking notifier chains, with
28 : * the same restrictions.
29 : *
30 : * atomic_notifier_chain_register() may be called from an atomic context,
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.
34 : *
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.
48 : */
49 :
50 : struct notifier_block {
51 : int (*notifier_call)(struct notifier_block *, unsigned long, void *);
52 : struct notifier_block *next;
53 : int priority;
54 : };
55 :
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 :
70 : struct srcu_notifier_head {
71 : struct mutex mutex;
72 : struct srcu_struct srcu;
73 : struct notifier_block *head;
74 : };
75 :
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 :
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 :
93 : #define ATOMIC_NOTIFIER_INIT(name) { \
94 : .lock = __SPIN_LOCK_UNLOCKED(name.lock), \
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 }
101 : /* srcu_notifier_heads cannot be initialized statically */
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)
112 :
113 : #ifdef __KERNEL__
114 :
115 : extern int atomic_notifier_chain_register(struct atomic_notifier_head *nh,
116 : struct notifier_block *nb);
117 : extern int blocking_notifier_chain_register(struct blocking_notifier_head *nh,
118 : struct notifier_block *nb);
119 : extern int raw_notifier_chain_register(struct raw_notifier_head *nh,
120 : struct notifier_block *nb);
121 : extern int srcu_notifier_chain_register(struct srcu_notifier_head *nh,
122 : struct notifier_block *nb);
123 :
124 : extern int blocking_notifier_chain_cond_register(
125 : struct blocking_notifier_head *nh,
126 : struct notifier_block *nb);
127 :
128 : extern int atomic_notifier_chain_unregister(struct atomic_notifier_head *nh,
129 : struct notifier_block *nb);
130 : extern int blocking_notifier_chain_unregister(struct blocking_notifier_head *nh,
131 : struct notifier_block *nb);
132 : extern int raw_notifier_chain_unregister(struct raw_notifier_head *nh,
133 : struct notifier_block *nb);
134 : extern int srcu_notifier_chain_unregister(struct srcu_notifier_head *nh,
135 : struct notifier_block *nb);
136 :
137 : extern int atomic_notifier_call_chain(struct atomic_notifier_head *nh,
138 : unsigned long val, void *v);
139 : extern int __atomic_notifier_call_chain(struct atomic_notifier_head *nh,
140 : unsigned long val, void *v, int nr_to_call, int *nr_calls);
141 : extern int blocking_notifier_call_chain(struct blocking_notifier_head *nh,
142 : unsigned long val, void *v);
143 : extern int __blocking_notifier_call_chain(struct blocking_notifier_head *nh,
144 : unsigned long val, void *v, int nr_to_call, int *nr_calls);
145 : extern int raw_notifier_call_chain(struct raw_notifier_head *nh,
146 : unsigned long val, void *v);
147 : extern int __raw_notifier_call_chain(struct raw_notifier_head *nh,
148 : unsigned long val, void *v, int nr_to_call, int *nr_calls);
149 : extern int srcu_notifier_call_chain(struct srcu_notifier_head *nh,
150 : unsigned long val, void *v);
151 : extern int __srcu_notifier_call_chain(struct srcu_notifier_head *nh,
152 : unsigned long val, void *v, int nr_to_call, int *nr_calls);
153 :
154 : #define NOTIFY_DONE 0x0000 /* Don't care */
155 : #define NOTIFY_OK 0x0001 /* Suits me */
156 : #define NOTIFY_STOP_MASK 0x8000 /* Don't call further */
157 : #define NOTIFY_BAD (NOTIFY_STOP_MASK|0x0002)
158 : /* Bad/Veto action */
159 : /*
160 : * Clean way to return from the notifier and stop further calls.
161 : */
162 : #define NOTIFY_STOP (NOTIFY_OK|NOTIFY_STOP_MASK)
163 :
164 : /* Encapsulate (negative) errno value (in particular, NOTIFY_BAD <=> EPERM). */
165 : static inline int notifier_from_errno(int err)
166 : {
167 : return NOTIFY_STOP_MASK | (NOTIFY_OK - err);
168 : }
169 :
170 : /* Restore (negative) errno value from notify return value. */
171 : static inline int notifier_to_errno(int ret)
172 : {
173 : ret &= ~NOTIFY_STOP_MASK;
174 : return ret > NOTIFY_OK ? NOTIFY_OK - ret : 0;
175 : }
176 :
177 : /*
178 : * Declared notifiers so far. I can imagine quite a few more chains
179 : * over time (eg laptop power reset chains, reboot chain (to clean
180 : * device units up), device [un]mount chain, module load/unload chain,
181 : * low memory chain, screenblank chain (for plug in modular screenblankers)
182 : * VC switch chains (for loadable kernel svgalib VC switch helpers) etc...
183 : */
184 :
185 : /* netdevice notifier chain */
186 : #define NETDEV_UP 0x0001 /* For now you can't veto a device up/down */
187 : #define NETDEV_DOWN 0x0002
188 : #define NETDEV_REBOOT 0x0003 /* Tell a protocol stack a network interface
189 : detected a hardware crash and restarted
190 : - we can use this eg to kick tcp sessions
191 : once done */
192 : #define NETDEV_CHANGE 0x0004 /* Notify device state change */
193 : #define NETDEV_REGISTER 0x0005
194 : #define NETDEV_UNREGISTER 0x0006
195 : #define NETDEV_CHANGEMTU 0x0007
196 : #define NETDEV_CHANGEADDR 0x0008
197 : #define NETDEV_GOING_DOWN 0x0009
198 : #define NETDEV_CHANGENAME 0x000A
199 : #define NETDEV_FEAT_CHANGE 0x000B
200 : #define NETDEV_BONDING_FAILOVER 0x000C
201 : #define NETDEV_PRE_UP 0x000D
202 : #define NETDEV_BONDING_OLDTYPE 0x000E
203 : #define NETDEV_BONDING_NEWTYPE 0x000F
204 : #define NETDEV_POST_INIT 0x0010
205 : #define NETDEV_UNREGISTER_BATCH 0x0011
206 :
207 : #define SYS_DOWN 0x0001 /* Notify of system down */
208 : #define SYS_RESTART SYS_DOWN
209 : #define SYS_HALT 0x0002 /* Notify of system halt */
210 : #define SYS_POWER_OFF 0x0003 /* Notify of system power off */
211 :
212 : #define NETLINK_URELEASE 0x0001 /* Unicast netlink socket released */
213 :
214 : #define CPU_ONLINE 0x0002 /* CPU (unsigned)v is up */
215 : #define CPU_UP_PREPARE 0x0003 /* CPU (unsigned)v coming up */
216 : #define CPU_UP_CANCELED 0x0004 /* CPU (unsigned)v NOT coming up */
217 : #define CPU_DOWN_PREPARE 0x0005 /* CPU (unsigned)v going down */
218 : #define CPU_DOWN_FAILED 0x0006 /* CPU (unsigned)v NOT going down */
219 : #define CPU_DEAD 0x0007 /* CPU (unsigned)v dead */
220 : #define CPU_DYING 0x0008 /* CPU (unsigned)v not running any task,
221 : * not handling interrupts, soon dead.
222 : * Called on the dying cpu, interrupts
223 : * are already disabled. Must not
224 : * sleep, must not fail */
225 : #define CPU_POST_DEAD 0x0009 /* CPU (unsigned)v dead, cpu_hotplug
226 : * lock is dropped */
227 : #define CPU_STARTING 0x000A /* CPU (unsigned)v soon running.
228 : * Called on the new cpu, just before
229 : * enabling interrupts. Must not sleep,
230 : * must not fail */
231 :
232 : /* Used for CPU hotplug events occuring while tasks are frozen due to a suspend
233 : * operation in progress
234 : */
235 : #define CPU_TASKS_FROZEN 0x0010
236 :
237 : #define CPU_ONLINE_FROZEN (CPU_ONLINE | CPU_TASKS_FROZEN)
238 : #define CPU_UP_PREPARE_FROZEN (CPU_UP_PREPARE | CPU_TASKS_FROZEN)
239 : #define CPU_UP_CANCELED_FROZEN (CPU_UP_CANCELED | CPU_TASKS_FROZEN)
240 : #define CPU_DOWN_PREPARE_FROZEN (CPU_DOWN_PREPARE | CPU_TASKS_FROZEN)
241 : #define CPU_DOWN_FAILED_FROZEN (CPU_DOWN_FAILED | CPU_TASKS_FROZEN)
242 : #define CPU_DEAD_FROZEN (CPU_DEAD | CPU_TASKS_FROZEN)
243 : #define CPU_DYING_FROZEN (CPU_DYING | CPU_TASKS_FROZEN)
244 : #define CPU_STARTING_FROZEN (CPU_STARTING | CPU_TASKS_FROZEN)
245 :
246 : /* Hibernation and suspend events */
247 : #define PM_HIBERNATION_PREPARE 0x0001 /* Going to hibernate */
248 : #define PM_POST_HIBERNATION 0x0002 /* Hibernation finished */
249 : #define PM_SUSPEND_PREPARE 0x0003 /* Going to suspend the system */
250 : #define PM_POST_SUSPEND 0x0004 /* Suspend finished */
251 : #define PM_RESTORE_PREPARE 0x0005 /* Going to restore a saved image */
252 : #define PM_POST_RESTORE 0x0006 /* Restore failed */
253 :
254 : /* Console keyboard events.
255 : * Note: KBD_KEYCODE is always sent before KBD_UNBOUND_KEYCODE, KBD_UNICODE and
256 : * KBD_KEYSYM. */
257 : #define KBD_KEYCODE 0x0001 /* Keyboard keycode, called before any other */
258 : #define KBD_UNBOUND_KEYCODE 0x0002 /* Keyboard keycode which is not bound to any other */
259 : #define KBD_UNICODE 0x0003 /* Keyboard unicode */
260 : #define KBD_KEYSYM 0x0004 /* Keyboard keysym */
261 : #define KBD_POST_KEYSYM 0x0005 /* Called after keyboard keysym interpretation */
262 :
263 : extern struct blocking_notifier_head reboot_notifier_list;
264 1 :
265 : /* Virtual Terminal events. */
266 : #define VT_ALLOCATE 0x0001 /* Console got allocated */
267 : #define VT_DEALLOCATE 0x0002 /* Console will be deallocated */
268 : #define VT_WRITE 0x0003 /* A char got output */
269 : #define VT_UPDATE 0x0004 /* A bigger update occurred */
270 : #define VT_PREWRITE 0x0005 /* A char is about to be written to the console */
271 :
272 : #endif /* __KERNEL__ */
273 : #endif /* _LINUX_NOTIFIER_H */
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