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/ktime.h>
   6 #include <uapi/linux/futex.h>
   7
   8 struct inode;
   9 struct mm_struct;
  10 struct task_struct;
  11
  12 long do_futex(u32 __user *uaddr, int op, u32 val, ktime_t *timeout,
  13               u32 __user *uaddr2, u32 val2, u32 val3);
  14
  15 extern int
  16 handle_futex_death(u32 __user *uaddr, struct task_struct *curr, int pi);
  17
  18 /*
  19  * Futexes are matched on equal values of this key.
  20  * The key type depends on whether it's a shared or private mapping.
  21  * Don't rearrange members without looking at hash_futex().
  22  *
  23  * offset is aligned to a multiple of sizeof(u32) (== 4) by definition.
  24  * We use the two low order bits of offset to tell what is the kind of key :
  25  *  00 : Private process futex (PTHREAD_PROCESS_PRIVATE)
  26  *       (no reference on an inode or mm)
  27  *  01 : Shared futex (PTHREAD_PROCESS_SHARED)
  28  *      mapped on a file (reference on the underlying inode)
  29  *  10 : Shared futex (PTHREAD_PROCESS_SHARED)
  30  *       (but private mapping on an mm, and reference taken on it)
  31 */
  32
  33 #define FUT_OFF_INODE    1 /* We set bit 0 if key has a reference on inode */
  34 #define FUT_OFF_MMSHARED 2 /* We set bit 1 if key has a reference on mm */
  35
  36 union futex_key {
  37         struct {
  38                 unsigned long pgoff;
  39                 struct inode *inode;
  40                 int offset;
  41         } shared;
  42         struct {
  43                 unsigned long address;
  44                 struct mm_struct *mm;
  45                 int offset;
  46         } private;
  47         struct {
  48                 unsigned long word;
  49                 void *ptr;
  50                 int offset;
  51         } both;
  52 };
  53
  54 #define FUTEX_KEY_INIT (union futex_key) { .both = { .ptr = NULL } }
  55
  56 #ifdef CONFIG_FUTEX
  57 extern void exit_robust_list(struct task_struct *curr);
  58 #ifdef CONFIG_HAVE_FUTEX_CMPXCHG
  59 #define futex_cmpxchg_enabled 1
  60 #else
  61 extern int futex_cmpxchg_enabled;
  62 #endif
  63 #else
  64 static inline void exit_robust_list(struct task_struct *curr)
  65 {
  66 }
  67 #endif
  68
  69 #ifdef CONFIG_FUTEX_PI
  70 extern void exit_pi_state_list(struct task_struct *curr);
  71 #else
  72 static inline void exit_pi_state_list(struct task_struct *curr)
  73 {
  74 }
  75 #endif
  76
  77 #endif