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/* $NetBSD: linux_futex.c,v 1.9 2007/11/04 11:10:34 rmind Exp $ */
/*-
* Copyright (c) 2005 Emmanuel Dreyfus, all rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by Emmanuel Dreyfus
* 4. The name of the author may not be used to endorse or promote
* products derived from this software without specific prior written
* permission.
*
* THIS SOFTWARE IS PROVIDED BY THE THE AUTHOR AND CONTRIBUTORS ``AS IS''
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(1, "$NetBSD: linux_futex.c,v 1.9 2007/11/04 11:10:34 rmind Exp $");
#include <sys/param.h>
#include <sys/time.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/lwp.h>
#include <sys/queue.h>
#include <sys/condvar.h>
#include <sys/mutex.h>
#include <sys/kmem.h>
#include <sys/kernel.h>
#include <compat/linux/common/linux_types.h>
#include <compat/linux/common/linux_signal.h>
#include <compat/linux/common/linux_futex.h>
#include <compat/linux/common/linux_ipc.h>
#include <compat/linux/common/linux_sem.h>
#include <compat/linux/linux_syscallargs.h>
struct futex;
struct waiting_proc {
kcondvar_t wp_futex_cv;
struct futex *wp_new_futex;
TAILQ_ENTRY(waiting_proc) wp_list;
};
struct futex {
void *f_uaddr;
int f_refcount;
LIST_ENTRY(futex) f_list;
TAILQ_HEAD(lf_waiting_proc, waiting_proc) f_waiting_proc;
};
static LIST_HEAD(futex_list, futex) futex_list;
static kmutex_t *futex_lock = NULL;
#define FUTEX_LOCK mutex_enter(futex_lock);
#define FUTEX_UNLOCK mutex_exit(futex_lock);
#ifdef DEBUG_LINUX_FUTEX
#define FUTEXPRINTF(a) printf a
#else
#define FUTEXPRINTF(a)
#endif
static struct futex *futex_get(void *);
static void futex_put(struct futex *);
static int futex_sleep(struct futex *, unsigned int);
static int futex_wake(struct futex *, int, struct futex *);
int
linux_sys_futex(struct lwp *l, void *v, register_t *retval)
{
struct linux_sys_futex_args /* {
syscallarg(int *) uaddr;
syscallarg(int) op;
syscallarg(int) val;
syscallarg(const struct timespec *) timeout;
syscallarg(int *) uaddr2;
syscallarg(int) val3;
} */ *uap = v;
int val;
int ret;
struct timespec timeout = { 0, 0 };
int error = 0;
struct futex *f;
struct futex *newf;
int timeout_hz = 0;
/* First time use */
if (__predict_false(futex_lock == NULL)) {
futex_lock = kmem_alloc(sizeof(kmutex_t), KM_SLEEP);
mutex_init(futex_lock, MUTEX_DEFAULT, IPL_NONE);
FUTEX_LOCK;
LIST_INIT(&futex_list);
FUTEX_UNLOCK;
}
switch (SCARG(uap, op)) {
case LINUX_FUTEX_WAIT:
if ((error = copyin(SCARG(uap, uaddr),
&val, sizeof(val))) != 0)
return error;
if (val != SCARG(uap, val))
return EWOULDBLOCK;
if (SCARG(uap, timeout) != NULL) {
if ((error = copyin(SCARG(uap, timeout),
&timeout, sizeof(timeout))) != 0)
return error;
error = itimespecfix(&timeout);
if (error)
return error;
timeout_hz = tstohz(&timeout);
}
FUTEXPRINTF(("FUTEX_WAIT %d.%d: val = %d, uaddr = %p, "
"*uaddr = %d, timeout = %d.%09ld\n",
l->l_proc->p_pid, l->l_lid, SCARG(uap, val),
SCARG(uap, uaddr), val, timeout.tv_sec, timeout.tv_nsec));
f = futex_get(SCARG(uap, uaddr));
ret = futex_sleep(f, timeout_hz);
futex_put(f);
FUTEXPRINTF(("FUTEX_WAIT %d.%d: uaddr = %p, "
"ret = %d\n", l->l_proc->p_pid, l->l_lid,
SCARG(uap, uaddr), ret));
switch (ret) {
case EWOULDBLOCK: /* timeout */
return ETIMEDOUT;
break;
case EINTR: /* signal */
return EINTR;
break;
case 0: /* FUTEX_WAKE received */
FUTEXPRINTF(("FUTEX_WAIT %d.%d: uaddr = %p, got it\n",
l->l_proc->p_pid, l->l_lid, SCARG(uap, uaddr)));
return 0;
break;
default:
FUTEXPRINTF(("FUTEX_WAIT: unexpected ret = %d\n", ret));
break;
}
/* NOTREACHED */
break;
case LINUX_FUTEX_WAKE:
/*
* XXX: Linux is able cope with different addresses
* corresponding to the same mapped memory in the sleeping
* and the waker process.
*/
FUTEXPRINTF(("FUTEX_WAKE %d.%d: uaddr = %p, val = %d\n",
l->l_proc->p_pid, l->l_lid,
SCARG(uap, uaddr), SCARG(uap, val)));
f = futex_get(SCARG(uap, uaddr));
*retval = futex_wake(f, SCARG(uap, val), NULL);
futex_put(f);
break;
case LINUX_FUTEX_CMP_REQUEUE:
if ((error = copyin(SCARG(uap, uaddr),
&val, sizeof(val))) != 0)
return error;
if (val != SCARG(uap, val3))
return EAGAIN;
/* FALLTHROUGH */
case LINUX_FUTEX_REQUEUE:
f = futex_get(SCARG(uap, uaddr));
newf = futex_get(SCARG(uap, uaddr2));
*retval = futex_wake(f, SCARG(uap, val), newf);
futex_put(f);
futex_put(newf);
break;
case LINUX_FUTEX_FD:
FUTEXPRINTF(("linux_sys_futex: unimplemented op %d\n",
SCARG(uap, op)));
break;
default:
FUTEXPRINTF(("linux_sys_futex: unknown op %d\n",
SCARG(uap, op)));
break;
}
return 0;
}
static struct futex *
futex_get(void *uaddr)
{
struct futex *f;
FUTEX_LOCK;
LIST_FOREACH(f, &futex_list, f_list) {
if (f->f_uaddr == uaddr) {
f->f_refcount++;
FUTEX_UNLOCK;
return f;
}
}
FUTEX_UNLOCK;
/* Not found, create it */
f = kmem_zalloc(sizeof(*f), KM_SLEEP);
f->f_uaddr = uaddr;
f->f_refcount = 1;
TAILQ_INIT(&f->f_waiting_proc);
FUTEX_LOCK;
LIST_INSERT_HEAD(&futex_list, f, f_list);
FUTEX_UNLOCK;
return f;
}
static void
futex_put(struct futex *f)
{
f->f_refcount--;
if (f->f_refcount == 0) {
FUTEX_LOCK;
LIST_REMOVE(f, f_list);
FUTEX_UNLOCK;
kmem_free(f, sizeof(*f));
}
return;
}
static int
futex_sleep(struct futex *f, unsigned int timeout)
{
struct waiting_proc *wp;
int ret;
wp = kmem_zalloc(sizeof(*wp), KM_SLEEP);
cv_init(&wp->wp_futex_cv, "lnxftxcv");
FUTEX_LOCK;
TAILQ_INSERT_TAIL(&f->f_waiting_proc, wp, wp_list);
ret = cv_timedwait_sig(&wp->wp_futex_cv, futex_lock, timeout);
TAILQ_REMOVE(&f->f_waiting_proc, wp, wp_list);
FUTEX_UNLOCK;
if ((ret == 0) && (wp->wp_new_futex != NULL)) {
ret = futex_sleep(wp->wp_new_futex, timeout);
futex_put(wp->wp_new_futex); /* futex_get called in wakeup */
}
kmem_free(wp, sizeof(*wp));
return ret;
}
static int
futex_wake(struct futex *f, int n, struct futex *newf)
{
struct waiting_proc *wp;
int count = 0;
FUTEX_LOCK;
TAILQ_FOREACH(wp, &f->f_waiting_proc, wp_list) {
if (count <= n) {
cv_broadcast(&wp->wp_futex_cv);
count++;
} else {
if (newf == NULL)
continue;
/* futex_put called after tsleep */
wp->wp_new_futex = futex_get(newf->f_uaddr);
cv_broadcast(&wp->wp_futex_cv);
}
}
FUTEX_UNLOCK;
return count;
}
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