Rev 6936 | Details | Compare with Previous | Last modification | View Log | RSS feed
| Rev | Author | Line No. | Line |
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| 6936 | serge | 1 | /* |
| 2 | * Routines to manage notifier chains for passing status changes to any |
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| 3 | * interested routines. We need this instead of hard coded call lists so |
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| 4 | * that modules can poke their nose into the innards. The network devices |
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| 5 | * needed them so here they are for the rest of you. |
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| 6 | * |
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| 7 | * Alan Cox |
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| 8 | */ |
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| 7143 | serge | 9 | |
| 6936 | serge | 10 | #ifndef _LINUX_NOTIFIER_H |
| 11 | #define _LINUX_NOTIFIER_H |
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| 12 | #include |
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| 13 | #include |
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| 14 | #include |
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| 15 | /* |
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| 16 | * Notifier chains are of four types: |
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| 17 | * |
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| 18 | * Atomic notifier chains: Chain callbacks run in interrupt/atomic |
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| 19 | * context. Callouts are not allowed to block. |
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| 20 | * Blocking notifier chains: Chain callbacks run in process context. |
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| 21 | * Callouts are allowed to block. |
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| 22 | * Raw notifier chains: There are no restrictions on callbacks, |
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| 23 | * registration, or unregistration. All locking and protection |
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| 24 | * must be provided by the caller. |
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| 25 | * SRCU notifier chains: A variant of blocking notifier chains, with |
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| 26 | * the same restrictions. |
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| 27 | * |
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| 28 | * atomic_notifier_chain_register() may be called from an atomic context, |
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| 29 | * but blocking_notifier_chain_register() and srcu_notifier_chain_register() |
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| 30 | * must be called from a process context. Ditto for the corresponding |
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| 31 | * _unregister() routines. |
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| 32 | * |
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| 33 | * atomic_notifier_chain_unregister(), blocking_notifier_chain_unregister(), |
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| 34 | * and srcu_notifier_chain_unregister() _must not_ be called from within |
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| 35 | * the call chain. |
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| 36 | * |
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| 37 | * SRCU notifier chains are an alternative form of blocking notifier chains. |
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| 38 | * They use SRCU (Sleepable Read-Copy Update) instead of rw-semaphores for |
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| 39 | * protection of the chain links. This means there is _very_ low overhead |
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| 40 | * in srcu_notifier_call_chain(): no cache bounces and no memory barriers. |
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| 41 | * As compensation, srcu_notifier_chain_unregister() is rather expensive. |
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| 42 | * SRCU notifier chains should be used when the chain will be called very |
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| 43 | * often but notifier_blocks will seldom be removed. Also, SRCU notifier |
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| 44 | * chains are slightly more difficult to use because they require special |
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| 45 | * runtime initialization. |
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| 46 | */ |
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| 47 | |||
| 48 | struct notifier_block; |
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| 49 | |||
| 50 | typedef int (*notifier_fn_t)(struct notifier_block *nb, |
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| 51 | unsigned long action, void *data); |
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| 52 | |||
| 53 | struct notifier_block { |
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| 54 | notifier_fn_t notifier_call; |
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| 55 | struct notifier_block __rcu *next; |
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| 56 | int priority; |
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| 57 | }; |
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| 58 | |||
| 59 | /* Console keyboard events. |
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| 60 | * Note: KBD_KEYCODE is always sent before KBD_UNBOUND_KEYCODE, KBD_UNICODE and |
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| 61 | * KBD_KEYSYM. */ |
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| 62 | #define KBD_KEYCODE 0x0001 /* Keyboard keycode, called before any other */ |
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| 63 | #define KBD_UNBOUND_KEYCODE 0x0002 /* Keyboard keycode which is not bound to any other */ |
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| 64 | #define KBD_UNICODE 0x0003 /* Keyboard unicode */ |
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| 65 | #define KBD_KEYSYM 0x0004 /* Keyboard keysym */ |
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| 66 | #define KBD_POST_KEYSYM 0x0005 /* Called after keyboard keysym interpretation */ |
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| 67 | |||
| 68 | |||
| 69 | #endif /* _LINUX_NOTIFIER_H */ |