include/linux/futex.h

   1 #ifndef _LINUX_FUTEX_H
   2 #define _LINUX_FUTEX_H
   3
   4 #include <uapi/linux/futex.h>
   5
   6 struct inode;
   7 struct mm_struct;
   8 struct task_struct;
   9 union ktime;
  10
  11 long do_futex(u32 __user *uaddr, int op, u32 val, union ktime *timeout,
  12               u32 __user *uaddr2, u32 val2, u32 val3);
  13
  14 extern int
  15 handle_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
  35 union 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
  56 extern void exit_robust_list(struct task_struct *curr);
  57 extern void exit_pi_state_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 static inline void exit_pi_state_list(struct task_struct *curr)
  68 {
  69 }
  70 #endif
  71 #endif