1 /* SPDX-License-Identifier: GPL-2.0 */ 2 #ifndef _LINUX_FUTEX_H 3 #define _LINUX_FUTEX_H 4 5 #include <linux/sched.h> 6 #include <linux/ktime.h> 7 8 #include <uapi/linux/futex.h> 9 10 struct inode; 11 struct mm_struct; 12 struct task_struct; 13 14 /* 15 * Futexes are matched on equal values of this key. 16 * The key type depends on whether it's a shared or private mapping. 17 * Don't rearrange members without looking at hash_futex(). 18 * 19 * offset is aligned to a multiple of sizeof(u32) (== 4) by definition. 20 * We use the two low order bits of offset to tell what is the kind of key : 21 * 00 : Private process futex (PTHREAD_PROCESS_PRIVATE) 22 * (no reference on an inode or mm) 23 * 01 : Shared futex (PTHREAD_PROCESS_SHARED) 24 * mapped on a file (reference on the underlying inode) 25 * 10 : Shared futex (PTHREAD_PROCESS_SHARED) 26 * (but private mapping on an mm, and reference taken on it) 27 */ 28 29 #define FUT_OFF_INODE 1 /* We set bit 0 if key has a reference on inode */ 30 #define FUT_OFF_MMSHARED 2 /* We set bit 1 if key has a reference on mm */ 31 32 union futex_key { 33 struct { 34 unsigned long pgoff; 35 struct inode *inode; 36 int offset; 37 } shared; 38 struct { 39 unsigned long address; 40 struct mm_struct *mm; 41 int offset; 42 } private; 43 struct { 44 unsigned long word; 45 void *ptr; 46 int offset; 47 } both; 48 }; 49 50 #define FUTEX_KEY_INIT (union futex_key) { .both = { .ptr = NULL } } 51 52 #ifdef CONFIG_FUTEX 53 enum { 54 FUTEX_STATE_OK, 55 FUTEX_STATE_EXITING, 56 FUTEX_STATE_DEAD, 57 }; 58 59 static inline void futex_init_task(struct task_struct *tsk) 60 { 61 tsk->robust_list = NULL; 62 #ifdef CONFIG_COMPAT 63 tsk->compat_robust_list = NULL; 64 #endif 65 INIT_LIST_HEAD(&tsk->pi_state_list); 66 tsk->pi_state_cache = NULL; 67 tsk->futex_state = FUTEX_STATE_OK; 68 mutex_init(&tsk->futex_exit_mutex); 69 } 70 71 void futex_exit_recursive(struct task_struct *tsk); 72 void futex_exit_release(struct task_struct *tsk); 73 void futex_exec_release(struct task_struct *tsk); 74 75 long do_futex(u32 __user *uaddr, int op, u32 val, ktime_t *timeout, 76 u32 __user *uaddr2, u32 val2, u32 val3); 77 #else 78 static inline void futex_init_task(struct task_struct *tsk) { } 79 static inline void futex_exit_recursive(struct task_struct *tsk) { } 80 static inline void futex_exit_release(struct task_struct *tsk) { } 81 static inline void futex_exec_release(struct task_struct *tsk) { } 82 static inline long do_futex(u32 __user *uaddr, int op, u32 val, 83 ktime_t *timeout, u32 __user *uaddr2, 84 u32 val2, u32 val3) 85 { 86 return -EINVAL; 87 } 88 #endif 89 90 #endif 91