root/include/linux/sem.h

/* */

INCLUDED FROM

   1 #ifndef _LINUX_SEM_H
   2 #define _LINUX_SEM_H
   3 #include <linux/ipc.h>
   4 
   5 /* semop flags */
   6 #define SEM_UNDO        0x1000  /* undo the operation on exit */
   7 
   8 /* semctl Command Definitions. */
   9 #define GETPID  11       /* get sempid */
  10 #define GETVAL  12       /* get semval */
  11 #define GETALL  13       /* get all semval's */
  12 #define GETNCNT 14       /* get semncnt */
  13 #define GETZCNT 15       /* get semzcnt */
  14 #define SETVAL  16       /* set semval */
  15 #define SETALL  17       /* set all semval's */
  16 
  17 /* One semid data structure for each set of semaphores in the system. */
  18 struct semid_ds {
  19   struct ipc_perm sem_perm;            /* permissions .. see ipc.h */
  20   time_t          sem_otime;           /* last semop time */
  21   time_t          sem_ctime;           /* last change time */
  22   struct sem      *sem_base;           /* ptr to first semaphore in array */
  23   struct sem_queue *sem_pending;       /* pending operations to be processed */
  24   struct sem_queue **sem_pending_last; /* last pending operation */
  25   struct sem_undo *undo;               /* undo requests on this array */
  26   ushort          sem_nsems;           /* no. of semaphores in array */
  27 };
  28 
  29 /* semop system calls takes an array of these. */
  30 struct sembuf {
  31   ushort  sem_num;        /* semaphore index in array */
  32   short   sem_op;         /* semaphore operation */
  33   short   sem_flg;        /* operation flags */
  34 };
  35 
  36 /* arg for semctl system calls. */
  37 union semun {
  38   int val;                      /* value for SETVAL */
  39   struct semid_ds *buf;         /* buffer for IPC_STAT & IPC_SET */
  40   ushort *array;                /* array for GETALL & SETALL */
  41   struct seminfo *__buf;        /* buffer for IPC_INFO */
  42   void *__pad;
  43 };
  44 
  45 struct  seminfo {
  46     int semmap;
  47     int semmni;
  48     int semmns;
  49     int semmnu;
  50     int semmsl;
  51     int semopm;
  52     int semume;
  53     int semusz;
  54     int semvmx;
  55     int semaem;
  56 };
  57 
  58 #define SEMMNI  128             /* ?  max # of semaphore identifiers */
  59 #define SEMMSL  32              /* <= 512 max num of semaphores per id */
  60 #define SEMMNS  (SEMMNI*SEMMSL) /* ? max # of semaphores in system */
  61 #define SEMOPM  32              /* ~ 100 max num of ops per semop call */
  62 #define SEMVMX  32767           /* semaphore maximum value */
  63 
  64 /* unused */
  65 #define SEMUME  SEMOPM          /* max num of undo entries per process */
  66 #define SEMMNU  SEMMNS          /* num of undo structures system wide */
  67 #define SEMAEM  (SEMVMX >> 1)   /* adjust on exit max value */
  68 #define SEMMAP  SEMMNS          /* # of entries in semaphore map */
  69 #define SEMUSZ  20              /* sizeof struct sem_undo */
  70 
  71 #ifdef __KERNEL__
  72 
  73 /* One semaphore structure for each semaphore in the system. */
  74 struct sem {
  75   short   semval;         /* current value */
  76   short   sempid;         /* pid of last operation */
  77 };
  78 
  79 /* ipcs ctl cmds */
  80 #define SEM_STAT 18
  81 #define SEM_INFO 19
  82 
  83 /* One queue for each semaphore set in the system. */
  84 struct sem_queue {
  85     struct sem_queue *  next;    /* next entry in the queue */
  86     struct sem_queue ** prev;    /* previous entry in the queue, *(q->prev) == q */
  87     struct wait_queue * sleeper; /* sleeping process */
  88     struct sem_undo *   undo;    /* undo structure */
  89     int                 pid;     /* process id of requesting process */
  90     int                 status;  /* completion status of operation */
  91     struct semid_ds *   sma;     /* semaphore array for operations */
  92     struct sembuf *     sops;    /* array of pending operations */
  93     int                 nsops;   /* number of operations */
  94 };
  95 
  96 /* Each task has a list of undo requests. They are executed automatically
  97  * when the process exits.
  98  */
  99 struct sem_undo {
 100     struct sem_undo *  proc_next; /* next entry on this process */
 101     struct sem_undo *  id_next;   /* next entry on this semaphore set */
 102     int                semid;     /* semaphore set identifier */
 103     short *            semadj;    /* array of adjustments, one per semaphore */
 104 };
 105 
 106 asmlinkage int sys_semget (key_t key, int nsems, int semflg);
 107 asmlinkage int sys_semop (int semid, struct sembuf *sops, unsigned nsops);
 108 asmlinkage int sys_semctl (int semid, int semnum, int cmd, union semun arg);
 109 
 110 #endif /* __KERNEL__ */
 111 
 112 #endif /* _LINUX_SEM_H */

/* */