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![Manfred Spraul](/assets/img/avatar_default.png)
Based on Nick's findings: sysv sem has the concept of semaphore arrays that consist out of multiple semaphores. Atomic operations that affect multiple semaphores are supported. The patch is the first step for optimizing simple, single semaphore operations: In addition to the global list of all pending operations, a 2nd, per-semaphore list with the simple operations is added. Note: this patch does not make sense by itself, the new list is used nowhere. Signed-off-by: Manfred Spraul <manfred@colorfullife.com> Cc: Nick Piggin <npiggin@suse.de> Cc: Pierre Peiffer <peifferp@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
162 lines
5.1 KiB
C
162 lines
5.1 KiB
C
#ifndef _LINUX_SEM_H
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#define _LINUX_SEM_H
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#include <linux/ipc.h>
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/* semop flags */
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#define SEM_UNDO 0x1000 /* undo the operation on exit */
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/* semctl Command Definitions. */
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#define GETPID 11 /* get sempid */
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#define GETVAL 12 /* get semval */
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#define GETALL 13 /* get all semval's */
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#define GETNCNT 14 /* get semncnt */
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#define GETZCNT 15 /* get semzcnt */
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#define SETVAL 16 /* set semval */
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#define SETALL 17 /* set all semval's */
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/* ipcs ctl cmds */
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#define SEM_STAT 18
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#define SEM_INFO 19
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/* Obsolete, used only for backwards compatibility and libc5 compiles */
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struct semid_ds {
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struct ipc_perm sem_perm; /* permissions .. see ipc.h */
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__kernel_time_t sem_otime; /* last semop time */
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__kernel_time_t sem_ctime; /* last change time */
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struct sem *sem_base; /* ptr to first semaphore in array */
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struct sem_queue *sem_pending; /* pending operations to be processed */
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struct sem_queue **sem_pending_last; /* last pending operation */
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struct sem_undo *undo; /* undo requests on this array */
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unsigned short sem_nsems; /* no. of semaphores in array */
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};
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/* Include the definition of semid64_ds */
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#include <asm/sembuf.h>
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/* semop system calls takes an array of these. */
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struct sembuf {
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unsigned short sem_num; /* semaphore index in array */
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short sem_op; /* semaphore operation */
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short sem_flg; /* operation flags */
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};
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/* arg for semctl system calls. */
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union semun {
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int val; /* value for SETVAL */
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struct semid_ds __user *buf; /* buffer for IPC_STAT & IPC_SET */
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unsigned short __user *array; /* array for GETALL & SETALL */
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struct seminfo __user *__buf; /* buffer for IPC_INFO */
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void __user *__pad;
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};
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struct seminfo {
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int semmap;
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int semmni;
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int semmns;
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int semmnu;
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int semmsl;
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int semopm;
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int semume;
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int semusz;
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int semvmx;
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int semaem;
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};
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#define SEMMNI 128 /* <= IPCMNI max # of semaphore identifiers */
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#define SEMMSL 250 /* <= 8 000 max num of semaphores per id */
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#define SEMMNS (SEMMNI*SEMMSL) /* <= INT_MAX max # of semaphores in system */
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#define SEMOPM 32 /* <= 1 000 max num of ops per semop call */
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#define SEMVMX 32767 /* <= 32767 semaphore maximum value */
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#define SEMAEM SEMVMX /* adjust on exit max value */
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/* unused */
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#define SEMUME SEMOPM /* max num of undo entries per process */
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#define SEMMNU SEMMNS /* num of undo structures system wide */
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#define SEMMAP SEMMNS /* # of entries in semaphore map */
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#define SEMUSZ 20 /* sizeof struct sem_undo */
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#ifdef __KERNEL__
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#include <asm/atomic.h>
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#include <linux/rcupdate.h>
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struct task_struct;
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/* One semaphore structure for each semaphore in the system. */
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struct sem {
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int semval; /* current value */
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int sempid; /* pid of last operation */
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struct list_head sem_pending; /* pending single-sop operations */
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};
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/* One sem_array data structure for each set of semaphores in the system. */
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struct sem_array {
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struct kern_ipc_perm sem_perm; /* permissions .. see ipc.h */
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time_t sem_otime; /* last semop time */
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time_t sem_ctime; /* last change time */
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struct sem *sem_base; /* ptr to first semaphore in array */
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struct list_head sem_pending; /* pending operations to be processed */
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struct list_head list_id; /* undo requests on this array */
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int sem_nsems; /* no. of semaphores in array */
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int complex_count; /* pending complex operations */
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};
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/* One queue for each sleeping process in the system. */
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struct sem_queue {
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struct list_head simple_list; /* queue of pending operations */
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struct list_head list; /* queue of pending operations */
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struct task_struct *sleeper; /* this process */
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struct sem_undo *undo; /* undo structure */
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int pid; /* process id of requesting process */
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int status; /* completion status of operation */
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struct sembuf *sops; /* array of pending operations */
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int nsops; /* number of operations */
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int alter; /* does the operation alter the array? */
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};
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/* Each task has a list of undo requests. They are executed automatically
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* when the process exits.
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*/
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struct sem_undo {
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struct list_head list_proc; /* per-process list: all undos from one process. */
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/* rcu protected */
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struct rcu_head rcu; /* rcu struct for sem_undo() */
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struct sem_undo_list *ulp; /* sem_undo_list for the process */
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struct list_head list_id; /* per semaphore array list: all undos for one array */
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int semid; /* semaphore set identifier */
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short * semadj; /* array of adjustments, one per semaphore */
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};
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/* sem_undo_list controls shared access to the list of sem_undo structures
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* that may be shared among all a CLONE_SYSVSEM task group.
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*/
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struct sem_undo_list {
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atomic_t refcnt;
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spinlock_t lock;
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struct list_head list_proc;
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};
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struct sysv_sem {
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struct sem_undo_list *undo_list;
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};
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#ifdef CONFIG_SYSVIPC
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extern int copy_semundo(unsigned long clone_flags, struct task_struct *tsk);
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extern void exit_sem(struct task_struct *tsk);
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#else
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static inline int copy_semundo(unsigned long clone_flags, struct task_struct *tsk)
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{
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return 0;
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}
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static inline void exit_sem(struct task_struct *tsk)
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{
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return;
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}
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#endif
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#endif /* __KERNEL__ */
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#endif /* _LINUX_SEM_H */
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