Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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> |
Alan Stern | e041c68 | 2006-03-27 01:16:30 -0800 | [diff] [blame] | 13 | #include <linux/mutex.h> |
| 14 | #include <linux/rwsem.h> |
Alan Stern | eabc069 | 2006-10-04 02:17:04 -0700 | [diff] [blame] | 15 | #include <linux/srcu.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 16 | |
Alan Stern | e041c68 | 2006-03-27 01:16:30 -0800 | [diff] [blame] | 17 | /* |
Alan Stern | eabc069 | 2006-10-04 02:17:04 -0700 | [diff] [blame] | 18 | * Notifier chains are of four types: |
Alan Stern | e041c68 | 2006-03-27 01:16:30 -0800 | [diff] [blame] | 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. |
Alan Stern | eabc069 | 2006-10-04 02:17:04 -0700 | [diff] [blame] | 27 | * SRCU notifier chains: A variant of blocking notifier chains, with |
| 28 | * the same restrictions. |
Alan Stern | e041c68 | 2006-03-27 01:16:30 -0800 | [diff] [blame] | 29 | * |
| 30 | * atomic_notifier_chain_register() may be called from an atomic context, |
Alan Stern | eabc069 | 2006-10-04 02:17:04 -0700 | [diff] [blame] | 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. |
Alan Stern | e041c68 | 2006-03-27 01:16:30 -0800 | [diff] [blame] | 34 | * |
Alan Stern | eabc069 | 2006-10-04 02:17:04 -0700 | [diff] [blame] | 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. |
Alan Stern | e041c68 | 2006-03-27 01:16:30 -0800 | [diff] [blame] | 48 | */ |
| 49 | |
| 50 | struct notifier_block { |
| 51 | int (*notifier_call)(struct notifier_block *, unsigned long, void *); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 52 | struct notifier_block *next; |
| 53 | int priority; |
| 54 | }; |
| 55 | |
Alan Stern | e041c68 | 2006-03-27 01:16:30 -0800 | [diff] [blame] | 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 | |
Alan Stern | eabc069 | 2006-10-04 02:17:04 -0700 | [diff] [blame] | 70 | struct srcu_notifier_head { |
| 71 | struct mutex mutex; |
| 72 | struct srcu_struct srcu; |
| 73 | struct notifier_block *head; |
| 74 | }; |
| 75 | |
Alan Stern | e041c68 | 2006-03-27 01:16:30 -0800 | [diff] [blame] | 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 | |
Alan Stern | eabc069 | 2006-10-04 02:17:04 -0700 | [diff] [blame] | 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 | |
Alan Stern | e041c68 | 2006-03-27 01:16:30 -0800 | [diff] [blame] | 93 | #define ATOMIC_NOTIFIER_INIT(name) { \ |
Ingo Molnar | e4d9191 | 2006-07-03 00:24:34 -0700 | [diff] [blame] | 94 | .lock = __SPIN_LOCK_UNLOCKED(name.lock), \ |
Alan Stern | e041c68 | 2006-03-27 01:16:30 -0800 | [diff] [blame] | 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 } |
Alan Stern | eabc069 | 2006-10-04 02:17:04 -0700 | [diff] [blame] | 101 | /* srcu_notifier_heads cannot be initialized statically */ |
Alan Stern | e041c68 | 2006-03-27 01:16:30 -0800 | [diff] [blame] | 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) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 112 | |
| 113 | #ifdef __KERNEL__ |
| 114 | |
Gautham R Shenoy | 6f7cc11 | 2007-05-09 02:34:02 -0700 | [diff] [blame] | 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); |
Alan Stern | e041c68 | 2006-03-27 01:16:30 -0800 | [diff] [blame] | 123 | |
Gautham R Shenoy | 6f7cc11 | 2007-05-09 02:34:02 -0700 | [diff] [blame] | 124 | extern int atomic_notifier_chain_unregister(struct atomic_notifier_head *nh, |
| 125 | struct notifier_block *nb); |
| 126 | extern int blocking_notifier_chain_unregister(struct blocking_notifier_head *nh, |
| 127 | struct notifier_block *nb); |
| 128 | extern int raw_notifier_chain_unregister(struct raw_notifier_head *nh, |
| 129 | struct notifier_block *nb); |
| 130 | extern int srcu_notifier_chain_unregister(struct srcu_notifier_head *nh, |
| 131 | struct notifier_block *nb); |
Alan Stern | e041c68 | 2006-03-27 01:16:30 -0800 | [diff] [blame] | 132 | |
Gautham R Shenoy | 6f7cc11 | 2007-05-09 02:34:02 -0700 | [diff] [blame] | 133 | extern int atomic_notifier_call_chain(struct atomic_notifier_head *nh, |
Alan Stern | e041c68 | 2006-03-27 01:16:30 -0800 | [diff] [blame] | 134 | unsigned long val, void *v); |
Gautham R Shenoy | 6f7cc11 | 2007-05-09 02:34:02 -0700 | [diff] [blame] | 135 | extern int __atomic_notifier_call_chain(struct atomic_notifier_head *nh, |
| 136 | unsigned long val, void *v, int nr_to_call, int *nr_calls); |
| 137 | extern int blocking_notifier_call_chain(struct blocking_notifier_head *nh, |
Alan Stern | e041c68 | 2006-03-27 01:16:30 -0800 | [diff] [blame] | 138 | unsigned long val, void *v); |
Gautham R Shenoy | 6f7cc11 | 2007-05-09 02:34:02 -0700 | [diff] [blame] | 139 | extern int __blocking_notifier_call_chain(struct blocking_notifier_head *nh, |
| 140 | unsigned long val, void *v, int nr_to_call, int *nr_calls); |
| 141 | extern int raw_notifier_call_chain(struct raw_notifier_head *nh, |
Alan Stern | e041c68 | 2006-03-27 01:16:30 -0800 | [diff] [blame] | 142 | unsigned long val, void *v); |
Gautham R Shenoy | 6f7cc11 | 2007-05-09 02:34:02 -0700 | [diff] [blame] | 143 | extern int __raw_notifier_call_chain(struct raw_notifier_head *nh, |
| 144 | unsigned long val, void *v, int nr_to_call, int *nr_calls); |
| 145 | extern int srcu_notifier_call_chain(struct srcu_notifier_head *nh, |
Alan Stern | eabc069 | 2006-10-04 02:17:04 -0700 | [diff] [blame] | 146 | unsigned long val, void *v); |
Gautham R Shenoy | 6f7cc11 | 2007-05-09 02:34:02 -0700 | [diff] [blame] | 147 | extern int __srcu_notifier_call_chain(struct srcu_notifier_head *nh, |
| 148 | unsigned long val, void *v, int nr_to_call, int *nr_calls); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 149 | |
| 150 | #define NOTIFY_DONE 0x0000 /* Don't care */ |
| 151 | #define NOTIFY_OK 0x0001 /* Suits me */ |
| 152 | #define NOTIFY_STOP_MASK 0x8000 /* Don't call further */ |
Alan Stern | e041c68 | 2006-03-27 01:16:30 -0800 | [diff] [blame] | 153 | #define NOTIFY_BAD (NOTIFY_STOP_MASK|0x0002) |
| 154 | /* Bad/Veto action */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 155 | /* |
| 156 | * Clean way to return from the notifier and stop further calls. |
| 157 | */ |
| 158 | #define NOTIFY_STOP (NOTIFY_OK|NOTIFY_STOP_MASK) |
| 159 | |
Herbert Xu | fcc5a03 | 2007-07-30 17:03:38 -0700 | [diff] [blame] | 160 | /* Encapsulate (negative) errno value (in particular, NOTIFY_BAD <=> EPERM). */ |
| 161 | static inline int notifier_from_errno(int err) |
| 162 | { |
| 163 | return NOTIFY_STOP_MASK | (NOTIFY_OK - err); |
| 164 | } |
| 165 | |
| 166 | /* Restore (negative) errno value from notify return value. */ |
| 167 | static inline int notifier_to_errno(int ret) |
| 168 | { |
| 169 | ret &= ~NOTIFY_STOP_MASK; |
| 170 | return ret > NOTIFY_OK ? NOTIFY_OK - ret : 0; |
| 171 | } |
| 172 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 173 | /* |
| 174 | * Declared notifiers so far. I can imagine quite a few more chains |
| 175 | * over time (eg laptop power reset chains, reboot chain (to clean |
| 176 | * device units up), device [un]mount chain, module load/unload chain, |
| 177 | * low memory chain, screenblank chain (for plug in modular screenblankers) |
| 178 | * VC switch chains (for loadable kernel svgalib VC switch helpers) etc... |
| 179 | */ |
| 180 | |
| 181 | /* netdevice notifier chain */ |
| 182 | #define NETDEV_UP 0x0001 /* For now you can't veto a device up/down */ |
| 183 | #define NETDEV_DOWN 0x0002 |
| 184 | #define NETDEV_REBOOT 0x0003 /* Tell a protocol stack a network interface |
| 185 | detected a hardware crash and restarted |
| 186 | - we can use this eg to kick tcp sessions |
| 187 | once done */ |
| 188 | #define NETDEV_CHANGE 0x0004 /* Notify device state change */ |
| 189 | #define NETDEV_REGISTER 0x0005 |
| 190 | #define NETDEV_UNREGISTER 0x0006 |
| 191 | #define NETDEV_CHANGEMTU 0x0007 |
| 192 | #define NETDEV_CHANGEADDR 0x0008 |
| 193 | #define NETDEV_GOING_DOWN 0x0009 |
| 194 | #define NETDEV_CHANGENAME 0x000A |
Stephen Hemminger | d8a33ac | 2005-05-29 14:13:47 -0700 | [diff] [blame] | 195 | #define NETDEV_FEAT_CHANGE 0x000B |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 196 | |
| 197 | #define SYS_DOWN 0x0001 /* Notify of system down */ |
| 198 | #define SYS_RESTART SYS_DOWN |
| 199 | #define SYS_HALT 0x0002 /* Notify of system halt */ |
| 200 | #define SYS_POWER_OFF 0x0003 /* Notify of system power off */ |
| 201 | |
| 202 | #define NETLINK_URELEASE 0x0001 /* Unicast netlink socket released */ |
| 203 | |
| 204 | #define CPU_ONLINE 0x0002 /* CPU (unsigned)v is up */ |
| 205 | #define CPU_UP_PREPARE 0x0003 /* CPU (unsigned)v coming up */ |
| 206 | #define CPU_UP_CANCELED 0x0004 /* CPU (unsigned)v NOT coming up */ |
| 207 | #define CPU_DOWN_PREPARE 0x0005 /* CPU (unsigned)v going down */ |
| 208 | #define CPU_DOWN_FAILED 0x0006 /* CPU (unsigned)v NOT going down */ |
| 209 | #define CPU_DEAD 0x0007 /* CPU (unsigned)v dead */ |
Gautham R Shenoy | baaca49 | 2007-05-09 02:34:03 -0700 | [diff] [blame] | 210 | #define CPU_LOCK_ACQUIRE 0x0008 /* Acquire all hotcpu locks */ |
| 211 | #define CPU_LOCK_RELEASE 0x0009 /* Release all hotcpu locks */ |
Avi Kivity | db912f9 | 2007-05-24 12:23:10 +0300 | [diff] [blame] | 212 | #define CPU_DYING 0x000A /* CPU (unsigned)v not running any task, |
| 213 | * not handling interrupts, soon dead */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 214 | |
Rafael J. Wysocki | 8bb7844 | 2007-05-09 02:35:10 -0700 | [diff] [blame] | 215 | /* Used for CPU hotplug events occuring while tasks are frozen due to a suspend |
| 216 | * operation in progress |
| 217 | */ |
| 218 | #define CPU_TASKS_FROZEN 0x0010 |
| 219 | |
| 220 | #define CPU_ONLINE_FROZEN (CPU_ONLINE | CPU_TASKS_FROZEN) |
| 221 | #define CPU_UP_PREPARE_FROZEN (CPU_UP_PREPARE | CPU_TASKS_FROZEN) |
| 222 | #define CPU_UP_CANCELED_FROZEN (CPU_UP_CANCELED | CPU_TASKS_FROZEN) |
| 223 | #define CPU_DOWN_PREPARE_FROZEN (CPU_DOWN_PREPARE | CPU_TASKS_FROZEN) |
| 224 | #define CPU_DOWN_FAILED_FROZEN (CPU_DOWN_FAILED | CPU_TASKS_FROZEN) |
| 225 | #define CPU_DEAD_FROZEN (CPU_DEAD | CPU_TASKS_FROZEN) |
Avi Kivity | db912f9 | 2007-05-24 12:23:10 +0300 | [diff] [blame] | 226 | #define CPU_DYING_FROZEN (CPU_DYING | CPU_TASKS_FROZEN) |
Rafael J. Wysocki | 8bb7844 | 2007-05-09 02:35:10 -0700 | [diff] [blame] | 227 | |
Rafael J. Wysocki | b10d911 | 2007-07-19 01:47:36 -0700 | [diff] [blame] | 228 | /* Hibernation and suspend events */ |
| 229 | #define PM_HIBERNATION_PREPARE 0x0001 /* Going to hibernate */ |
| 230 | #define PM_POST_HIBERNATION 0x0002 /* Hibernation finished */ |
| 231 | #define PM_SUSPEND_PREPARE 0x0003 /* Going to suspend the system */ |
| 232 | #define PM_POST_SUSPEND 0x0004 /* Suspend finished */ |
| 233 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 234 | #endif /* __KERNEL__ */ |
| 235 | #endif /* _LINUX_NOTIFIER_H */ |