root/include/asm-parisc/futex.h

INCLUDED FROM

DEFINITIONS

1. futex_atomic_op_inuser
2. futex_atomic_cmpxchg_inatomic

#ifndef _ASM_PARISC_FUTEX_H
#define _ASM_PARISC_FUTEX_H

#ifdef __KERNEL__

#include <linux/futex.h>
#include <linux/uaccess.h>
#include <asm/errno.h>

static inline int
futex_atomic_op_inuser (int encoded_op, int __user *uaddr)
{
        int op = (encoded_op >> 28) & 7;
        int cmp = (encoded_op >> 24) & 15;
        int oparg = (encoded_op << 8) >> 20;
        int cmparg = (encoded_op << 20) >> 20;
        int oldval = 0, ret;
        if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28))
                oparg = 1 << oparg;

        if (! access_ok (VERIFY_WRITE, uaddr, sizeof(int)))
                return -EFAULT;

        pagefault_disable();

        switch (op) {
        case FUTEX_OP_SET:
        case FUTEX_OP_ADD:
        case FUTEX_OP_OR:
        case FUTEX_OP_ANDN:
        case FUTEX_OP_XOR:
        default:
                ret = -ENOSYS;
        }

        pagefault_enable();

        if (!ret) {
                switch (cmp) {
                case FUTEX_OP_CMP_EQ: ret = (oldval == cmparg); break;
                case FUTEX_OP_CMP_NE: ret = (oldval != cmparg); break;
                case FUTEX_OP_CMP_LT: ret = (oldval < cmparg); break;
                case FUTEX_OP_CMP_GE: ret = (oldval >= cmparg); break;
                case FUTEX_OP_CMP_LE: ret = (oldval <= cmparg); break;
                case FUTEX_OP_CMP_GT: ret = (oldval > cmparg); break;
                default: ret = -ENOSYS;
                }
        }
        return ret;
}

/* Non-atomic version */
static inline int
futex_atomic_cmpxchg_inatomic(int __user *uaddr, int oldval, int newval)
{
        int err = 0;
        int uval;

        /* futex.c wants to do a cmpxchg_inatomic on kernel NULL, which is
         * our gateway page, and causes no end of trouble...
         */
        if (segment_eq(KERNEL_DS, get_fs()) && !uaddr)
                return -EFAULT;

        if (!access_ok(VERIFY_WRITE, uaddr, sizeof(int)))
                return -EFAULT;

        err = get_user(uval, uaddr);
        if (err) return -EFAULT;
        if (uval == oldval)
                err = put_user(newval, uaddr);
        if (err) return -EFAULT;
        return uval;
}

#endif /*__KERNEL__*/
#endif /*_ASM_PARISC_FUTEX_H*/