linux/include/linux/futex.h
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   1#ifndef _LINUX_FUTEX_H
   2#define _LINUX_FUTEX_H
   3
   4#include <uapi/linux/futex.h>
   5
   6struct inode;
   7struct mm_struct;
   8struct task_struct;
   9union ktime;
  10
  11long do_futex(u32 __user *uaddr, int op, u32 val, union ktime *timeout,
  12              u32 __user *uaddr2, u32 val2, u32 val3);
  13
  14extern int
  15handle_futex_death(u32 __user *uaddr, struct task_struct *curr, int pi);
  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
  35union 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
  56extern void exit_robust_list(struct task_struct *curr);
  57extern void exit_pi_state_list(struct task_struct *curr);
  58extern int futex_cmpxchg_enabled;
  59#else
  60static inline void exit_robust_list(struct task_struct *curr)
  61{
  62}
  63static inline void exit_pi_state_list(struct task_struct *curr)
  64{
  65}
  66#endif
  67#endif
  68
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