root/include/linux/sem.h

INCLUDED FROM

DEFINITIONS

1. copy_semundo
2. exit_sem

#ifndef _LINUX_SEM_H
#define _LINUX_SEM_H

#include <linux/ipc.h>

/* semop flags */
#define SEM_UNDO        0x1000  /* undo the operation on exit */

/* semctl Command Definitions. */
#define GETPID  11       /* get sempid */
#define GETVAL  12       /* get semval */
#define GETALL  13       /* get all semval's */
#define GETNCNT 14       /* get semncnt */
#define GETZCNT 15       /* get semzcnt */
#define SETVAL  16       /* set semval */
#define SETALL  17       /* set all semval's */

/* ipcs ctl cmds */
#define SEM_STAT 18
#define SEM_INFO 19

/* Obsolete, used only for backwards compatibility and libc5 compiles */
struct semid_ds {
        struct ipc_perm sem_perm;               /* permissions .. see ipc.h */
        __kernel_time_t sem_otime;              /* last semop time */
        __kernel_time_t sem_ctime;              /* last change time */
        struct sem      *sem_base;              /* ptr to first semaphore in array */
        struct sem_queue *sem_pending;          /* pending operations to be processed */
        struct sem_queue **sem_pending_last;    /* last pending operation */
        struct sem_undo *undo;                  /* undo requests on this array */
        unsigned short  sem_nsems;              /* no. of semaphores in array */
};

/* Include the definition of semid64_ds */
#include <asm/sembuf.h>

/* semop system calls takes an array of these. */
struct sembuf {
        unsigned short  sem_num;        /* semaphore index in array */
        short           sem_op;         /* semaphore operation */
        short           sem_flg;        /* operation flags */
};

/* arg for semctl system calls. */
union semun {
        int val;                        /* value for SETVAL */
        struct semid_ds __user *buf;    /* buffer for IPC_STAT & IPC_SET */
        unsigned short __user *array;   /* array for GETALL & SETALL */
        struct seminfo __user *__buf;   /* buffer for IPC_INFO */
        void __user *__pad;
};

struct  seminfo {
        int semmap;
        int semmni;
        int semmns;
        int semmnu;
        int semmsl;
        int semopm;
        int semume;
        int semusz;
        int semvmx;
        int semaem;
};

#define SEMMNI  128             /* <= IPCMNI  max # of semaphore identifiers */
#define SEMMSL  250             /* <= 8 000 max num of semaphores per id */
#define SEMMNS  (SEMMNI*SEMMSL) /* <= INT_MAX max # of semaphores in system */
#define SEMOPM  32              /* <= 1 000 max num of ops per semop call */
#define SEMVMX  32767           /* <= 32767 semaphore maximum value */
#define SEMAEM  SEMVMX          /* adjust on exit max value */

/* unused */
#define SEMUME  SEMOPM          /* max num of undo entries per process */
#define SEMMNU  SEMMNS          /* num of undo structures system wide */
#define SEMMAP  SEMMNS          /* # of entries in semaphore map */
#define SEMUSZ  20              /* sizeof struct sem_undo */

#ifdef __KERNEL__
#include <asm/atomic.h>
#include <linux/rcupdate.h>

struct task_struct;

/* One semaphore structure for each semaphore in the system. */
struct sem {
        int     semval;         /* current value */
        int     sempid;         /* pid of last operation */
};

/* One sem_array data structure for each set of semaphores in the system. */
struct sem_array {
        struct kern_ipc_perm    sem_perm;       /* permissions .. see ipc.h */
        time_t                  sem_otime;      /* last semop time */
        time_t                  sem_ctime;      /* last change time */
        struct sem              *sem_base;      /* ptr to first semaphore in array */
        struct list_head        sem_pending;    /* pending operations to be processed */
        struct list_head        list_id;        /* undo requests on this array */
        unsigned long           sem_nsems;      /* no. of semaphores in array */
};

/* One queue for each sleeping process in the system. */
struct sem_queue {
        struct list_head        list;    /* queue of pending operations */
        struct task_struct      *sleeper; /* this process */
        struct sem_undo         *undo;   /* undo structure */
        int                     pid;     /* process id of requesting process */
        int                     status;  /* completion status of operation */
        struct sembuf           *sops;   /* array of pending operations */
        int                     nsops;   /* number of operations */
        int                     alter;   /* does the operation alter the array? */
};

/* Each task has a list of undo requests. They are executed automatically
 * when the process exits.
 */
struct sem_undo {
        struct list_head        list_proc;      /* per-process list: all undos from one process. */
                                                /* rcu protected */
        struct rcu_head         rcu;            /* rcu struct for sem_undo() */
        struct sem_undo_list    *ulp;           /* sem_undo_list for the process */
        struct list_head        list_id;        /* per semaphore array list: all undos for one array */
        int                     semid;          /* semaphore set identifier */
        short *                 semadj;         /* array of adjustments, one per semaphore */
};

/* sem_undo_list controls shared access to the list of sem_undo structures
 * that may be shared among all a CLONE_SYSVSEM task group.
 */ 
struct sem_undo_list {
        atomic_t                refcnt;
        spinlock_t              lock;
        struct list_head        list_proc;
};

struct sysv_sem {
        struct sem_undo_list *undo_list;
};

#ifdef CONFIG_SYSVIPC

extern int copy_semundo(unsigned long clone_flags, struct task_struct *tsk);
extern void exit_sem(struct task_struct *tsk);

#else
static inline int copy_semundo(unsigned long clone_flags, struct task_struct *tsk)
{
        return 0;
}

static inline void exit_sem(struct task_struct *tsk)
{
        return;
}
#endif

#endif /* __KERNEL__ */

#endif /* _LINUX_SEM_H */