314 lines
7.9 KiB
C
314 lines
7.9 KiB
C
/* $NetBSD: linux_futex.c,v 1.13 2008/04/30 14:07:13 ad Exp $ */
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/*-
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* Copyright (c) 2005 Emmanuel Dreyfus, all rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by Emmanuel Dreyfus
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* 4. The name of the author may not be used to endorse or promote
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* products derived from this software without specific prior written
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* permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE THE AUTHOR AND CONTRIBUTORS ``AS IS''
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
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* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS
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* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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__KERNEL_RCSID(1, "$NetBSD: linux_futex.c,v 1.13 2008/04/30 14:07:13 ad Exp $");
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#include <sys/param.h>
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#include <sys/time.h>
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#include <sys/systm.h>
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#include <sys/proc.h>
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#include <sys/lwp.h>
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#include <sys/queue.h>
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#include <sys/condvar.h>
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#include <sys/mutex.h>
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#include <sys/kmem.h>
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#include <sys/kernel.h>
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#include <compat/linux/common/linux_types.h>
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#include <compat/linux/common/linux_signal.h>
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#include <compat/linux/common/linux_futex.h>
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#include <compat/linux/common/linux_ipc.h>
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#include <compat/linux/common/linux_sem.h>
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#include <compat/linux/linux_syscallargs.h>
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struct futex;
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struct waiting_proc {
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kcondvar_t wp_futex_cv;
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struct futex *wp_new_futex;
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TAILQ_ENTRY(waiting_proc) wp_list;
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};
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struct futex {
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void *f_uaddr;
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int f_refcount;
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LIST_ENTRY(futex) f_list;
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TAILQ_HEAD(lf_waiting_proc, waiting_proc) f_waiting_proc;
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};
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static LIST_HEAD(futex_list, futex) futex_list;
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static kmutex_t *futex_lock = NULL;
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#define FUTEX_LOCK mutex_enter(futex_lock);
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#define FUTEX_UNLOCK mutex_exit(futex_lock);
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#ifdef DEBUG_LINUX_FUTEX
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#define FUTEXPRINTF(a) printf a
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#else
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#define FUTEXPRINTF(a)
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#endif
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static struct futex *futex_get(void *);
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static void futex_put(struct futex *);
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static int futex_sleep(struct futex *, unsigned int);
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static int futex_wake(struct futex *, int, struct futex *);
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int
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linux_sys_futex(struct lwp *l, const struct linux_sys_futex_args *uap, register_t *retval)
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{
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/* {
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syscallarg(int *) uaddr;
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syscallarg(int) op;
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syscallarg(int) val;
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syscallarg(const struct timespec *) timeout;
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syscallarg(int *) uaddr2;
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syscallarg(int) val3;
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} */
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int val;
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int ret;
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struct timespec timeout = { 0, 0 };
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int error = 0;
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struct futex *f;
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struct futex *newf;
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int timeout_hz = 0;
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kmutex_t *lock;
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/* First time use */
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if (__predict_false(futex_lock == NULL)) {
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lock = mutex_obj_alloc(MUTEX_DEFAULT, IPL_NONE);
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mutex_enter(proc_lock);
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if (futex_lock == NULL) {
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futex_lock = lock;
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lock = NULL;
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LIST_INIT(&futex_list);
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}
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mutex_exit(proc_lock);
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if (lock != NULL)
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mutex_obj_free(lock);
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}
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switch (SCARG(uap, op)) {
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case LINUX_FUTEX_WAIT:
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if ((error = copyin(SCARG(uap, uaddr),
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&val, sizeof(val))) != 0)
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return error;
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if (val != SCARG(uap, val))
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return EWOULDBLOCK;
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if (SCARG(uap, timeout) != NULL) {
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if ((error = copyin(SCARG(uap, timeout),
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&timeout, sizeof(timeout))) != 0)
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return error;
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error = itimespecfix(&timeout);
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if (error)
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return error;
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timeout_hz = tstohz(&timeout);
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}
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FUTEXPRINTF(("FUTEX_WAIT %d.%d: val = %d, uaddr = %p, "
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"*uaddr = %d, timeout = %lld.%09ld\n",
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l->l_proc->p_pid, l->l_lid, SCARG(uap, val),
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SCARG(uap, uaddr), val, (long long)timeout.tv_sec,
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timeout.tv_nsec));
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f = futex_get(SCARG(uap, uaddr));
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ret = futex_sleep(f, timeout_hz);
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futex_put(f);
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FUTEXPRINTF(("FUTEX_WAIT %d.%d: uaddr = %p, "
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"ret = %d\n", l->l_proc->p_pid, l->l_lid,
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SCARG(uap, uaddr), ret));
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switch (ret) {
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case EWOULDBLOCK: /* timeout */
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return ETIMEDOUT;
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break;
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case EINTR: /* signal */
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return EINTR;
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break;
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case 0: /* FUTEX_WAKE received */
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FUTEXPRINTF(("FUTEX_WAIT %d.%d: uaddr = %p, got it\n",
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l->l_proc->p_pid, l->l_lid, SCARG(uap, uaddr)));
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return 0;
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break;
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default:
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FUTEXPRINTF(("FUTEX_WAIT: unexpected ret = %d\n", ret));
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break;
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}
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/* NOTREACHED */
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break;
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case LINUX_FUTEX_WAKE:
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/*
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* XXX: Linux is able cope with different addresses
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* corresponding to the same mapped memory in the sleeping
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* and the waker process.
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*/
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FUTEXPRINTF(("FUTEX_WAKE %d.%d: uaddr = %p, val = %d\n",
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l->l_proc->p_pid, l->l_lid,
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SCARG(uap, uaddr), SCARG(uap, val)));
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f = futex_get(SCARG(uap, uaddr));
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*retval = futex_wake(f, SCARG(uap, val), NULL);
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futex_put(f);
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break;
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case LINUX_FUTEX_CMP_REQUEUE:
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if ((error = copyin(SCARG(uap, uaddr),
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&val, sizeof(val))) != 0)
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return error;
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if (val != SCARG(uap, val3))
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return EAGAIN;
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/* FALLTHROUGH */
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case LINUX_FUTEX_REQUEUE:
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f = futex_get(SCARG(uap, uaddr));
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newf = futex_get(SCARG(uap, uaddr2));
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*retval = futex_wake(f, SCARG(uap, val), newf);
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futex_put(f);
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futex_put(newf);
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break;
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case LINUX_FUTEX_FD:
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FUTEXPRINTF(("linux_sys_futex: unimplemented op %d\n",
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SCARG(uap, op)));
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break;
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default:
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FUTEXPRINTF(("linux_sys_futex: unknown op %d\n",
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SCARG(uap, op)));
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break;
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}
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return 0;
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}
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static struct futex *
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futex_get(void *uaddr)
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{
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struct futex *f, *f2;
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FUTEX_LOCK;
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LIST_FOREACH(f, &futex_list, f_list) {
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if (f->f_uaddr == uaddr) {
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f->f_refcount++;
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FUTEX_UNLOCK;
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return f;
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}
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}
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FUTEX_UNLOCK;
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/* Not found, create it */
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f2 = kmem_zalloc(sizeof(*f2), KM_SLEEP);
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f2->f_uaddr = uaddr;
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f2->f_refcount = 1;
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TAILQ_INIT(&f2->f_waiting_proc);
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FUTEX_LOCK;
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LIST_FOREACH(f, &futex_list, f_list) {
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if (f->f_uaddr == uaddr) {
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f->f_refcount++;
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FUTEX_UNLOCK;
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kmem_free(f2, sizeof(*f2));
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return f;
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}
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}
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LIST_INSERT_HEAD(&futex_list, f2, f_list);
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FUTEX_UNLOCK;
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return f2;
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}
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static void
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futex_put(struct futex *f)
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{
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FUTEX_LOCK;
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f->f_refcount--;
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if (f->f_refcount == 0) {
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LIST_REMOVE(f, f_list);
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kmem_free(f, sizeof(*f));
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}
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FUTEX_UNLOCK;
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return;
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}
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static int
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futex_sleep(struct futex *f, unsigned int timeout)
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{
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struct waiting_proc *wp;
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int ret;
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wp = kmem_zalloc(sizeof(*wp), KM_SLEEP);
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cv_init(&wp->wp_futex_cv, "futex");
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FUTEX_LOCK;
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TAILQ_INSERT_TAIL(&f->f_waiting_proc, wp, wp_list);
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ret = cv_timedwait_sig(&wp->wp_futex_cv, futex_lock, timeout);
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TAILQ_REMOVE(&f->f_waiting_proc, wp, wp_list);
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FUTEX_UNLOCK;
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if ((ret == 0) && (wp->wp_new_futex != NULL)) {
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ret = futex_sleep(wp->wp_new_futex, timeout);
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futex_put(wp->wp_new_futex); /* futex_get called in wakeup */
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}
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kmem_free(wp, sizeof(*wp));
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return ret;
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}
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static int
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futex_wake(struct futex *f, int n, struct futex *newf)
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{
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struct waiting_proc *wp;
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int count = 0;
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FUTEX_LOCK;
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TAILQ_FOREACH(wp, &f->f_waiting_proc, wp_list) {
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if (count <= n) {
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cv_broadcast(&wp->wp_futex_cv);
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count++;
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} else {
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if (newf == NULL)
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continue;
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/* futex_put called after tsleep */
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wp->wp_new_futex = futex_get(newf->f_uaddr);
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cv_broadcast(&wp->wp_futex_cv);
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}
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}
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FUTEX_UNLOCK;
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return count;
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}
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