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/sched.h>
   6#include <linux/ktime.h>
   7
   8#include <uapi/linux/futex.h>
   9
  10struct inode;
  11struct mm_struct;
  12struct 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
  32union futex_key {
  33        struct {
  34                u64 i_seq;
  35                unsigned long pgoff;
  36                unsigned int offset;
  37        } shared;
  38        struct {
  39                union {
  40                        struct mm_struct *mm;
  41                        u64 __tmp;
  42                };
  43                unsigned long address;
  44                unsigned int offset;
  45        } private;
  46        struct {
  47                u64 ptr;
  48                unsigned long word;
  49                unsigned int offset;
  50        } both;
  51};
  52
  53#define FUTEX_KEY_INIT (union futex_key) { .both = { .ptr = 0ULL } }
  54
  55#ifdef CONFIG_FUTEX
  56enum {
  57        FUTEX_STATE_OK,
  58        FUTEX_STATE_EXITING,
  59        FUTEX_STATE_DEAD,
  60};
  61
  62static inline void futex_init_task(struct task_struct *tsk)
  63{
  64        tsk->robust_list = NULL;
  65#ifdef CONFIG_COMPAT
  66        tsk->compat_robust_list = NULL;
  67#endif
  68        INIT_LIST_HEAD(&tsk->pi_state_list);
  69        tsk->pi_state_cache = NULL;
  70        tsk->futex_state = FUTEX_STATE_OK;
  71        mutex_init(&tsk->futex_exit_mutex);
  72}
  73
  74void futex_exit_recursive(struct task_struct *tsk);
  75void futex_exit_release(struct task_struct *tsk);
  76void futex_exec_release(struct task_struct *tsk);
  77
  78long do_futex(u32 __user *uaddr, int op, u32 val, ktime_t *timeout,
  79              u32 __user *uaddr2, u32 val2, u32 val3);
  80#else
  81static inline void futex_init_task(struct task_struct *tsk) { }
  82static inline void futex_exit_recursive(struct task_struct *tsk) { }
  83static inline void futex_exit_release(struct task_struct *tsk) { }
  84static inline void futex_exec_release(struct task_struct *tsk) { }
  85static inline long do_futex(u32 __user *uaddr, int op, u32 val,
  86                            ktime_t *timeout, u32 __user *uaddr2,
  87                            u32 val2, u32 val3)
  88{
  89        return -EINVAL;
  90}
  91#endif
  92
  93#endif
  94