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#ifndef _LINUX_FUTEX_H

#define _LINUX_FUTEX_H

#include <linux/types.h>

/* Second argument to futex syscall */

#define FUTEX_WAIT              0

#define FUTEX_WAKE              1

#define FUTEX_FD                2

#define FUTEX_REQUEUE           3

#define FUTEX_CMP_REQUEUE       4

#define FUTEX_WAKE_OP           5

#define FUTEX_LOCK_PI           6

#define FUTEX_UNLOCK_PI         7

#define FUTEX_TRYLOCK_PI        8

#define FUTEX_WAIT_BITSET       9

#define FUTEX_WAKE_BITSET       10

#define FUTEX_WAIT_REQUEUE_PI   11

#define FUTEX_CMP_REQUEUE_PI    12

#define FUTEX_PRIVATE_FLAG      128

#define FUTEX_CLOCK_REALTIME    256

#define FUTEX_CMD_MASK          ~(FUTEX_PRIVATE_FLAG | FUTEX_CLOCK_REALTIME)

#define FUTEX_WAIT_PRIVATE      (FUTEX_WAIT | FUTEX_PRIVATE_FLAG)

#define FUTEX_WAKE_PRIVATE      (FUTEX_WAKE | FUTEX_PRIVATE_FLAG)

#define FUTEX_REQUEUE_PRIVATE   (FUTEX_REQUEUE | FUTEX_PRIVATE_FLAG)

#define FUTEX_CMP_REQUEUE_PRIVATE (FUTEX_CMP_REQUEUE | FUTEX_PRIVATE_FLAG)

#define FUTEX_WAKE_OP_PRIVATE   (FUTEX_WAKE_OP | FUTEX_PRIVATE_FLAG)

#define FUTEX_LOCK_PI_PRIVATE   (FUTEX_LOCK_PI | FUTEX_PRIVATE_FLAG)

#define FUTEX_UNLOCK_PI_PRIVATE (FUTEX_UNLOCK_PI | FUTEX_PRIVATE_FLAG)

#define FUTEX_TRYLOCK_PI_PRIVATE (FUTEX_TRYLOCK_PI | FUTEX_PRIVATE_FLAG)

#define FUTEX_WAIT_BITSET_PRIVATE       (FUTEX_WAIT_BITSET | FUTEX_PRIVATE_FLAG)

#define FUTEX_WAKE_BITSET_PRIVATE       (FUTEX_WAKE_BITSET | FUTEX_PRIVATE_FLAG)

#define FUTEX_WAIT_REQUEUE_PI_PRIVATE   (FUTEX_WAIT_REQUEUE_PI | \

                                         FUTEX_PRIVATE_FLAG)

#define FUTEX_CMP_REQUEUE_PI_PRIVATE    (FUTEX_CMP_REQUEUE_PI | \

                                         FUTEX_PRIVATE_FLAG)

/*

 * Support for robust futexes: the kernel cleans up held futexes at

 * thread exit time.

 */

/*

 * Per-lock list entry - embedded in user-space locks, somewhere close

 * to the futex field. (Note: user-space uses a double-linked list to

 * achieve O(1) list add and remove, but the kernel only needs to know

 * about the forward link)

 *

 * NOTE: this structure is part of the syscall ABI, and must not be

 * changed.

 */

struct robust_list {

        struct robust_list *next;

};

/*

 * Per-thread list head:

 *

 * NOTE: this structure is part of the syscall ABI, and must only be

 * changed if the change is first communicated with the glibc folks.

 * (When an incompatible change is done, we'll increase the structure

 *  size, which glibc will detect)

 */

struct robust_list_head {

        /*

         * The head of the list. Points back to itself if empty:

         */

        struct robust_list list;

        /*

         * This relative offset is set by user-space, it gives the kernel

         * the relative position of the futex field to examine. This way

         * we keep userspace flexible, to freely shape its data-structure,

         * without hardcoding any particular offset into the kernel:

         */

        long futex_offset;

        /*

         * The death of the thread may race with userspace setting

         * up a lock's links. So to handle this race, userspace first

         * sets this field to the address of the to-be-taken lock,

         * then does the lock acquire, and then adds itself to the

         * list, and then clears this field. Hence the kernel will

         * always have full knowledge of all locks that the thread

         * _might_ have taken. We check the owner TID in any case,

         * so only truly owned locks will be handled.

         */

        struct robust_list *list_op_pending;

};

/*

 * Are there any waiters for this robust futex:

 */

#define FUTEX_WAITERS           0x80000000

/*

 * The kernel signals via this bit that a thread holding a futex

 * has exited without unlocking the futex. The kernel also does

 * a FUTEX_WAKE on such futexes, after setting the bit, to wake

 * up any possible waiters:

 */

#define FUTEX_OWNER_DIED        0x40000000

/*

 * The rest of the robust-futex field is for the TID:

 */

#define FUTEX_TID_MASK          0x3fffffff

/*

 * This limit protects against a deliberately circular list.

 * (Not worth introducing an rlimit for it)

 */

#define ROBUST_LIST_LIMIT       2048

/*

 * bitset with all bits set for the FUTEX_xxx_BITSET OPs to request a

 * match of any bit.

 */

#define FUTEX_BITSET_MATCH_ANY  0xffffffff

#define FUTEX_OP_SET            0        /* *(int *)UADDR2 = OPARG; */

#define FUTEX_OP_ADD            1       /* *(int *)UADDR2 += OPARG; */

#define FUTEX_OP_OR             2       /* *(int *)UADDR2 |= OPARG; */

#define FUTEX_OP_ANDN           3       /* *(int *)UADDR2 &= ~OPARG; */

#define FUTEX_OP_XOR            4       /* *(int *)UADDR2 ^= OPARG; */

#define FUTEX_OP_OPARG_SHIFT    8       /* Use (1 << OPARG) instead of OPARG.  */

#define FUTEX_OP_CMP_EQ         0        /* if (oldval == CMPARG) wake */

#define FUTEX_OP_CMP_NE         1       /* if (oldval != CMPARG) wake */

#define FUTEX_OP_CMP_LT         2       /* if (oldval < CMPARG) wake */

#define FUTEX_OP_CMP_LE         3       /* if (oldval <= CMPARG) wake */

#define FUTEX_OP_CMP_GT         4       /* if (oldval > CMPARG) wake */

#define FUTEX_OP_CMP_GE         5       /* if (oldval >= CMPARG) wake */

/* FUTEX_WAKE_OP will perform atomically

   int oldval = *(int *)UADDR2;

   *(int *)UADDR2 = oldval OP OPARG;

   if (oldval CMP CMPARG)

     wake UADDR2;  */

#define FUTEX_OP(op, oparg, cmp, cmparg) \

  (((op & 0xf) << 28) | ((cmp & 0xf) << 24)             \

   | ((oparg & 0xfff) << 12) | (cmparg & 0xfff))

#endif /* _LINUX_FUTEX_H */