Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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kernel
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linux
1#ifndef _LINUX_SEM_H
2#define _LINUX_SEM_H
3
4#include <linux/atomic.h>
5#include <linux/rcupdate.h>
6#include <linux/cache.h>
7#include <uapi/linux/sem.h>
8
9struct task_struct;
10
11/* One semaphore structure for each semaphore in the system. */
12struct sem {
13 int semval; /* current value */
14 /*
15 * PID of the process that last modified the semaphore. For
16 * Linux, specifically these are:
17 * - semop
18 * - semctl, via SETVAL and SETALL.
19 * - at task exit when performing undo adjustments (see exit_sem).
20 */
21 int sempid;
22 spinlock_t lock; /* spinlock for fine-grained semtimedop */
23 struct list_head pending_alter; /* pending single-sop operations */
24 /* that alter the semaphore */
25 struct list_head pending_const; /* pending single-sop operations */
26 /* that do not alter the semaphore*/
27 time_t sem_otime; /* candidate for sem_otime */
28} ____cacheline_aligned_in_smp;
29
30/* One sem_array data structure for each set of semaphores in the system. */
31struct sem_array {
32 struct kern_ipc_perm sem_perm; /* permissions .. see ipc.h */
33 time_t sem_ctime; /* create/last semctl() time */
34 struct list_head pending_alter; /* pending operations */
35 /* that alter the array */
36 struct list_head pending_const; /* pending complex operations */
37 /* that do not alter semvals */
38 struct list_head list_id; /* undo requests on this array */
39 int sem_nsems; /* no. of semaphores in array */
40 int complex_count; /* pending complex operations */
41 unsigned int use_global_lock;/* >0: global lock required */
42
43 struct sem sems[];
44} __randomize_layout;
45
46#ifdef CONFIG_SYSVIPC
47
48struct sysv_sem {
49 struct sem_undo_list *undo_list;
50};
51
52extern int copy_semundo(unsigned long clone_flags, struct task_struct *tsk);
53extern void exit_sem(struct task_struct *tsk);
54
55#else
56
57struct sysv_sem {
58 /* empty */
59};
60
61static inline int copy_semundo(unsigned long clone_flags, struct task_struct *tsk)
62{
63 return 0;
64}
65
66static inline void exit_sem(struct task_struct *tsk)
67{
68 return;
69}
70#endif
71
72#endif /* _LINUX_SEM_H */