include/linux/futex.h

   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 long do_futex(u32 __user *uaddr, int op, u32 val, ktime_t *timeout,
  15               u32 __user *uaddr2, u32 val2, u32 val3);
  16
  17 /*
  18  * Futexes are matched on equal values of this key.
  19  * The key type depends on whether it's a shared or private mapping.
  20  * Don't rearrange members without looking at hash_futex().
  21  *
  22  * offset is aligned to a multiple of sizeof(u32) (== 4) by definition.
  23  * We use the two low order bits of offset to tell what is the kind of key :
  24  *  00 : Private process futex (PTHREAD_PROCESS_PRIVATE)
  25  *       (no reference on an inode or mm)
  26  *  01 : Shared futex (PTHREAD_PROCESS_SHARED)
  27  *      mapped on a file (reference on the underlying inode)
  28  *  10 : Shared futex (PTHREAD_PROCESS_SHARED)
  29  *       (but private mapping on an mm, and reference taken on it)
  30 */
  31
  32 #define FUT_OFF_INODE    1 /* We set bit 0 if key has a reference on inode */
  33 #define FUT_OFF_MMSHARED 2 /* We set bit 1 if key has a reference on mm */
  34
  35 union futex_key {
  36         struct {
  37                 unsigned long pgoff;
  38                 struct inode *inode;
  39                 int offset;
  40         } shared;
  41         struct {
  42                 unsigned long address;
  43                 struct mm_struct *mm;
  44                 int offset;
  45         } private;
  46         struct {
  47                 unsigned long word;
  48                 void *ptr;
  49                 int offset;
  50         } both;
  51 };
  52
  53 #define FUTEX_KEY_INIT (union futex_key) { .both = { .ptr = NULL } }
  54
  55 #ifdef CONFIG_FUTEX
  56
  57 static inline void futex_init_task(struct task_struct *tsk)
  58 {
  59         tsk->robust_list = NULL;
  60 #ifdef CONFIG_COMPAT
  61         tsk->compat_robust_list = NULL;
  62 #endif
  63         INIT_LIST_HEAD(&tsk->pi_state_list);
  64         tsk->pi_state_cache = NULL;
  65 }
  66
  67 void futex_mm_release(struct task_struct *tsk);
  68
  69 long do_futex(u32 __user *uaddr, int op, u32 val, ktime_t *timeout,
  70               u32 __user *uaddr2, u32 val2, u32 val3);
  71 #else
  72 static inline void futex_init_task(struct task_struct *tsk) { }
  73 static inline void futex_mm_release(struct task_struct *tsk) { }
  74 #endif
  75
  76 #endif