1 /* SPDX-License-Identifier: GPL-2.0 */ 2 #ifndef _LINUX_SEM_H 3 #define _LINUX_SEM_H 4 5 #include <linux/atomic.h> 6 #include <linux/rcupdate.h> 7 #include <linux/cache.h> 8 #include <linux/time64.h> 9 #include <uapi/linux/sem.h> 10 11 struct task_struct; 12 13 /* One semaphore structure for each semaphore in the system. */ 14 struct sem { 15 int semval; /* current value */ 16 /* 17 * PID of the process that last modified the semaphore. For 18 * Linux, specifically these are: 19 * - semop 20 * - semctl, via SETVAL and SETALL. 21 * - at task exit when performing undo adjustments (see exit_sem). 22 */ 23 int sempid; 24 spinlock_t lock; /* spinlock for fine-grained semtimedop */ 25 struct list_head pending_alter; /* pending single-sop operations */ 26 /* that alter the semaphore */ 27 struct list_head pending_const; /* pending single-sop operations */ 28 /* that do not alter the semaphore*/ 29 time_t sem_otime; /* candidate for sem_otime */ 30 } ____cacheline_aligned_in_smp; 31 32 /* One sem_array data structure for each set of semaphores in the system. */ 33 struct sem_array { 34 struct kern_ipc_perm sem_perm; /* permissions .. see ipc.h */ 35 time64_t sem_ctime; /* create/last semctl() time */ 36 struct list_head pending_alter; /* pending operations */ 37 /* that alter the array */ 38 struct list_head pending_const; /* pending complex operations */ 39 /* that do not alter semvals */ 40 struct list_head list_id; /* undo requests on this array */ 41 int sem_nsems; /* no. of semaphores in array */ 42 int complex_count; /* pending complex operations */ 43 unsigned int use_global_lock;/* >0: global lock required */ 44 45 struct sem sems[]; 46 } __randomize_layout; 47 48 #ifdef CONFIG_SYSVIPC 49 50 struct sysv_sem { 51 struct sem_undo_list *undo_list; 52 }; 53 54 extern int copy_semundo(unsigned long clone_flags, struct task_struct *tsk); 55 extern void exit_sem(struct task_struct *tsk); 56 57 #else 58 59 struct sysv_sem { 60 /* empty */ 61 }; 62 copy_semundo(unsigned long clone_flags,struct task_struct * tsk)63static inline int copy_semundo(unsigned long clone_flags, struct task_struct *tsk) 64 { 65 return 0; 66 } 67 exit_sem(struct task_struct * tsk)68static inline void exit_sem(struct task_struct *tsk) 69 { 70 return; 71 } 72 #endif 73 74 #endif /* _LINUX_SEM_H */ 75