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