2 * Copyright (c) 2005 David Xu <davidxu@freebsd.org>
3 * Copyright (c) 2005 Matthew Dillon <dillon@backplane.com>
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
35 #include "thr_private.h"
37 #define cpu_ccfence() __asm __volatile("" : : : "memory")
40 * This function is used to acquire a contested lock.
42 * A *mtx value of 1 indicates locked normally.
43 * A *mtx value of 2 indicates locked and contested.
46 __thr_umtx_lock(volatile umtx_t *mtx, int id, int timo)
60 if (atomic_fcmpset_int(mtx, &v, id))
71 * Set the waiting bit. If the fcmpset fails v is loaded
72 * with the current content of the mutex, and if the waiting
73 * bit is already set, we can also sleep.
75 if (atomic_fcmpset_int(mtx, &v, v|0x40000000) ||
78 _umtx_sleep_err(mtx, v|0x40000000, timo);
79 } else if ((errval = _umtx_sleep_err(mtx, v|0x40000000, timo)) > 0) {
80 if (errval == EAGAIN) {
81 if (atomic_cmpset_acq_int(mtx, 0, id))
95 * Inline followup when releasing a mutex. The mutex has been released
96 * but 'v' either doesn't match id or needs a wakeup.
99 __thr_umtx_unlock(volatile umtx_t *mtx, int v, int id)
101 if (v & 0x40000000) {
102 _umtx_wakeup_err(mtx, 0);
105 THR_ASSERT(v == id, "thr_umtx_unlock: wrong owner");
109 * Low level timed umtx lock. This function must never return
113 __thr_umtx_timedlock(volatile umtx_t *mtx, int id,
114 const struct timespec *timeout)
116 struct timespec ts, ts2, ts3;
119 if ((timeout->tv_sec < 0) ||
120 (timeout->tv_sec == 0 && timeout->tv_nsec <= 0)) {
124 /* XXX there should have MONO timer! */
125 clock_gettime(CLOCK_REALTIME, &ts);
126 TIMESPEC_ADD(&ts, &ts, timeout);
133 timo = (int)(ts2.tv_nsec / 1000);
139 ret = __thr_umtx_lock(mtx, id, timo);
140 if (ret != EINTR && ret != ETIMEDOUT)
142 clock_gettime(CLOCK_REALTIME, &ts3);
143 TIMESPEC_SUB(&ts2, &ts, &ts3);
144 if (ts2.tv_sec < 0 ||
145 (ts2.tv_sec == 0 && ts2.tv_nsec <= 0)) {
154 * Regular umtx wait that cannot return EINTR
157 _thr_umtx_wait(volatile umtx_t *mtx, int exp, const struct timespec *timeout,
160 struct timespec ts, ts2, ts3;
161 int timo, errval, ret = 0;
167 if (timeout == NULL) {
169 * NOTE: If no timeout, EINTR cannot be returned. Ignore
172 while ((errval = _umtx_sleep_err(mtx, exp, 10000000)) > 0) {
176 if (errval == ETIMEDOUT || errval == EWOULDBLOCK) {
179 "thr_umtx_wait: FAULT VALUE CHANGE "
180 "%d -> %d oncond %p\n",
192 * Timed waits can return EINTR
194 if ((timeout->tv_sec < 0) ||
195 (timeout->tv_sec == 0 && timeout->tv_nsec <= 0))
198 clock_gettime(clockid, &ts);
199 TIMESPEC_ADD(&ts, &ts, timeout);
204 timo = (int)(ts2.tv_nsec / 1000);
211 if ((errval = _umtx_sleep_err(mtx, exp, timo)) > 0) {
212 if (errval == EBUSY) {
216 if (errval == EINTR) {
222 clock_gettime(clockid, &ts3);
223 TIMESPEC_SUB(&ts2, &ts, &ts3);
224 if (ts2.tv_sec < 0 || (ts2.tv_sec == 0 && ts2.tv_nsec <= 0)) {
233 * Simple version without a timeout which can also return EINTR
236 _thr_umtx_wait_intr(volatile umtx_t *mtx, int exp)
245 errval = _umtx_sleep_err(mtx, exp, 10000000);
250 if (errval == EINTR) {
260 _thr_umtx_wake(volatile umtx_t *mtx, int count)
262 _umtx_wakeup_err(mtx, count);