LCOV - code coverage report
Current view: top level - include/linux - notifier.h (source / functions) Hit Total Coverage
Test: coverage.info Lines: 1 1 100.0 %
Date: 2017-01-25 Functions: 0 0 -

          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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