LXR linux/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
   8struct inode;
   9struct mm_struct;
  10struct task_struct;
  11
  12long do_futex(u32 __user *uaddr, int op, u32 val, ktime_t *timeout,
  13              u32 __user *uaddr2, u32 val2, u32 val3);
  14
  15extern int
  16handle_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
  36union 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
  57extern void exit_robust_list(struct task_struct *curr);
  58#ifdef CONFIG_HAVE_FUTEX_CMPXCHG
  59#define futex_cmpxchg_enabled 1
  60#else
  61extern int futex_cmpxchg_enabled;
  62#endif
  63#else
  64static inline void exit_robust_list(struct task_struct *curr)
  65{
  66}
  67#endif
  68
  69#ifdef CONFIG_FUTEX_PI
  70extern void exit_pi_state_list(struct task_struct *curr);
  71#else
  72static inline void exit_pi_state_list(struct task_struct *curr)
  73{
  74}
  75#endif
  76
  77#endif
  78