LXR linux/include/linux/futex.h

   1#ifndef _LINUX_FUTEX_H
   2#define _LINUX_FUTEX_H
   3
   4#include <linux/compiler.h>
   5#include <linux/types.h>
   6
   7struct inode;
   8struct mm_struct;
   9struct task_struct;
  10union ktime;
  11
  12/* Second argument to futex syscall */
  13
  14
  15#define FUTEX_WAIT              0
  16#define FUTEX_WAKE              1
  17#define FUTEX_FD                2
  18#define FUTEX_REQUEUE           3
  19#define FUTEX_CMP_REQUEUE       4
  20#define FUTEX_WAKE_OP           5
  21#define FUTEX_LOCK_PI           6
  22#define FUTEX_UNLOCK_PI         7
  23#define FUTEX_TRYLOCK_PI        8
  24#define FUTEX_WAIT_BITSET       9
  25#define FUTEX_WAKE_BITSET       10
  26
  27#define FUTEX_PRIVATE_FLAG      128
  28#define FUTEX_CMD_MASK          ~FUTEX_PRIVATE_FLAG
  29
  30#define FUTEX_WAIT_PRIVATE      (FUTEX_WAIT | FUTEX_PRIVATE_FLAG)
  31#define FUTEX_WAKE_PRIVATE      (FUTEX_WAKE | FUTEX_PRIVATE_FLAG)
  32#define FUTEX_REQUEUE_PRIVATE   (FUTEX_REQUEUE | FUTEX_PRIVATE_FLAG)
  33#define FUTEX_CMP_REQUEUE_PRIVATE (FUTEX_CMP_REQUEUE | FUTEX_PRIVATE_FLAG)
  34#define FUTEX_WAKE_OP_PRIVATE   (FUTEX_WAKE_OP | FUTEX_PRIVATE_FLAG)
  35#define FUTEX_LOCK_PI_PRIVATE   (FUTEX_LOCK_PI | FUTEX_PRIVATE_FLAG)
  36#define FUTEX_UNLOCK_PI_PRIVATE (FUTEX_UNLOCK_PI | FUTEX_PRIVATE_FLAG)
  37#define FUTEX_TRYLOCK_PI_PRIVATE (FUTEX_TRYLOCK_PI | FUTEX_PRIVATE_FLAG)
  38#define FUTEX_WAIT_BITSET_PRIVATE       (FUTEX_WAIT_BITS | FUTEX_PRIVATE_FLAG)
  39#define FUTEX_WAKE_BITSET_PRIVATE       (FUTEX_WAKE_BITS | FUTEX_PRIVATE_FLAG)
  40
  41/*
  42 * Support for robust futexes: the kernel cleans up held futexes at
  43 * thread exit time.
  44 */
  45
  46/*
  47 * Per-lock list entry - embedded in user-space locks, somewhere close
  48 * to the futex field. (Note: user-space uses a double-linked list to
  49 * achieve O(1) list add and remove, but the kernel only needs to know
  50 * about the forward link)
  51 *
  52 * NOTE: this structure is part of the syscall ABI, and must not be
  53 * changed.
  54 */
  55struct robust_list {
  56        struct robust_list __user *next;
  57};
  58
  59/*
  60 * Per-thread list head:
  61 *
  62 * NOTE: this structure is part of the syscall ABI, and must only be
  63 * changed if the change is first communicated with the glibc folks.
  64 * (When an incompatible change is done, we'll increase the structure
  65 *  size, which glibc will detect)
  66 */
  67struct robust_list_head {
  68        /*
  69         * The head of the list. Points back to itself if empty:
  70         */
  71        struct robust_list list;
  72
  73        /*
  74         * This relative offset is set by user-space, it gives the kernel
  75         * the relative position of the futex field to examine. This way
  76         * we keep userspace flexible, to freely shape its data-structure,
  77         * without hardcoding any particular offset into the kernel:
  78         */
  79        long futex_offset;
  80
  81        /*
  82         * The death of the thread may race with userspace setting
  83         * up a lock's links. So to handle this race, userspace first
  84         * sets this field to the address of the to-be-taken lock,
  85         * then does the lock acquire, and then adds itself to the
  86         * list, and then clears this field. Hence the kernel will
  87         * always have full knowledge of all locks that the thread
  88         * _might_ have taken. We check the owner TID in any case,
  89         * so only truly owned locks will be handled.
  90         */
  91        struct robust_list __user *list_op_pending;
  92};
  93
  94/*
  95 * Are there any waiters for this robust futex:
  96 */
  97#define FUTEX_WAITERS           0x80000000
  98
  99/*
 100 * The kernel signals via this bit that a thread holding a futex
 101 * has exited without unlocking the futex. The kernel also does
 102 * a FUTEX_WAKE on such futexes, after setting the bit, to wake
 103 * up any possible waiters:
 104 */
 105#define FUTEX_OWNER_DIED        0x40000000
 106
 107/*
 108 * The rest of the robust-futex field is for the TID:
 109 */
 110#define FUTEX_TID_MASK          0x3fffffff
 111
 112/*
 113 * This limit protects against a deliberately circular list.
 114 * (Not worth introducing an rlimit for it)
 115 */
 116#define ROBUST_LIST_LIMIT       2048
 117
 118/*
 119 * bitset with all bits set for the FUTEX_xxx_BITSET OPs to request a
 120 * match of any bit.
 121 */
 122#define FUTEX_BITSET_MATCH_ANY  0xffffffff
 123
 124#ifdef __KERNEL__
 125long do_futex(u32 __user *uaddr, int op, u32 val, union ktime *timeout,
 126              u32 __user *uaddr2, u32 val2, u32 val3);
 127
 128extern int
 129handle_futex_death(u32 __user *uaddr, struct task_struct *curr, int pi);
 130
 131/*
 132 * Futexes are matched on equal values of this key.
 133 * The key type depends on whether it's a shared or private mapping.
 134 * Don't rearrange members without looking at hash_futex().
 135 *
 136 * offset is aligned to a multiple of sizeof(u32) (== 4) by definition.
 137 * We use the two low order bits of offset to tell what is the kind of key :
 138 *  00 : Private process futex (PTHREAD_PROCESS_PRIVATE)
 139 *       (no reference on an inode or mm)
 140 *  01 : Shared futex (PTHREAD_PROCESS_SHARED)
 141 *      mapped on a file (reference on the underlying inode)
 142 *  10 : Shared futex (PTHREAD_PROCESS_SHARED)
 143 *       (but private mapping on an mm, and reference taken on it)
 144*/
 145
 146#define FUT_OFF_INODE    1 /* We set bit 0 if key has a reference on inode */
 147#define FUT_OFF_MMSHARED 2 /* We set bit 1 if key has a reference on mm */
 148
 149union futex_key {
 150        struct {
 151                unsigned long pgoff;
 152                struct inode *inode;
 153                int offset;
 154        } shared;
 155        struct {
 156                unsigned long address;
 157                struct mm_struct *mm;
 158                int offset;
 159        } private;
 160        struct {
 161                unsigned long word;
 162                void *ptr;
 163                int offset;
 164        } both;
 165};
 166
 167#ifdef CONFIG_FUTEX
 168extern void exit_robust_list(struct task_struct *curr);
 169extern void exit_pi_state_list(struct task_struct *curr);
 170extern int futex_cmpxchg_enabled;
 171#else
 172static inline void exit_robust_list(struct task_struct *curr)
 173{
 174}
 175static inline void exit_pi_state_list(struct task_struct *curr)
 176{
 177}
 178#endif
 179#endif /* __KERNEL__ */
 180
 181#define FUTEX_OP_SET            0       /* *(int *)UADDR2 = OPARG; */
 182#define FUTEX_OP_ADD            1       /* *(int *)UADDR2 += OPARG; */
 183#define FUTEX_OP_OR             2       /* *(int *)UADDR2 |= OPARG; */
 184#define FUTEX_OP_ANDN           3       /* *(int *)UADDR2 &= ~OPARG; */
 185#define FUTEX_OP_XOR            4       /* *(int *)UADDR2 ^= OPARG; */
 186
 187#define FUTEX_OP_OPARG_SHIFT    8       /* Use (1 << OPARG) instead of OPARG.  */
 188
 189#define FUTEX_OP_CMP_EQ         0       /* if (oldval == CMPARG) wake */
 190#define FUTEX_OP_CMP_NE         1       /* if (oldval != CMPARG) wake */
 191#define FUTEX_OP_CMP_LT         2       /* if (oldval < CMPARG) wake */
 192#define FUTEX_OP_CMP_LE         3       /* if (oldval <= CMPARG) wake */
 193#define FUTEX_OP_CMP_GT         4       /* if (oldval > CMPARG) wake */
 194#define FUTEX_OP_CMP_GE         5       /* if (oldval >= CMPARG) wake */
 195
 196/* FUTEX_WAKE_OP will perform atomically
 197   int oldval = *(int *)UADDR2;
 198   *(int *)UADDR2 = oldval OP OPARG;
 199   if (oldval CMP CMPARG)
 200     wake UADDR2;  */
 201
 202#define FUTEX_OP(op, oparg, cmp, cmparg) \
 203  (((op & 0xf) << 28) | ((cmp & 0xf) << 24)             \
 204   | ((oparg & 0xfff) << 12) | (cmparg & 0xfff))
 205
 206#endif
 207