2 * Copyright (c) 2005 The DragonFly Project. All rights reserved.
4 * This code is derived from software contributed to The DragonFly Project
5 * by 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
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in
15 * the documentation and/or other materials provided with the
17 * 3. Neither the name of The DragonFly Project nor the names of its
18 * contributors may be used to endorse or promote products derived
19 * from this software without specific, prior written permission.
21 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
22 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
23 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
24 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
25 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
26 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
27 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
28 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
29 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
30 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
31 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
35 * This API provides a fast locked-bus-cycle-based serializer. It's
36 * basically a low level NON-RECURSIVE exclusive lock that can be held across
37 * a blocking condition. It is NOT a mutex.
39 * This serializer is primarily designed for low level situations and
40 * interrupt/device interaction. There are two primary facilities. First,
41 * the serializer facility itself. Second, an integrated interrupt handler
42 * disablement facility.
45 #include <sys/param.h>
46 #include <sys/systm.h>
47 #include <sys/kernel.h>
49 #include <sys/rtprio.h>
50 #include <sys/queue.h>
51 #include <sys/thread2.h>
52 #include <sys/serialize.h>
53 #include <sys/sysctl.h>
55 #include <sys/kthread.h>
56 #include <machine/cpu.h>
57 #include <machine/cpufunc.h>
58 #include <machine/specialreg.h>
59 #include <machine/clock.h>
62 #ifndef SLZ_ADAPTIVE_SPINMAX
63 #define SLZ_ADAPTIVE_SPINMAX 4096
66 #define SLZ_KTR_STRING "slz=%p"
67 #define SLZ_KTR_ARGS lwkt_serialize_t slz
69 #ifndef KTR_SERIALIZER
70 #define KTR_SERIALIZER KTR_ALL
74 KTR_INFO(KTR_SERIALIZER, slz, enter_beg, 0, SLZ_KTR_STRING, SLZ_KTR_ARGS);
75 KTR_INFO(KTR_SERIALIZER, slz, sleep_beg, 1, SLZ_KTR_STRING, SLZ_KTR_ARGS);
76 KTR_INFO(KTR_SERIALIZER, slz, sleep_end, 2, SLZ_KTR_STRING, SLZ_KTR_ARGS);
77 KTR_INFO(KTR_SERIALIZER, slz, exit_end, 3, SLZ_KTR_STRING, SLZ_KTR_ARGS);
78 KTR_INFO(KTR_SERIALIZER, slz, wakeup_beg, 4, SLZ_KTR_STRING, SLZ_KTR_ARGS);
79 KTR_INFO(KTR_SERIALIZER, slz, wakeup_end, 5, SLZ_KTR_STRING, SLZ_KTR_ARGS);
80 KTR_INFO(KTR_SERIALIZER, slz, try, 6, SLZ_KTR_STRING, SLZ_KTR_ARGS);
81 KTR_INFO(KTR_SERIALIZER, slz, tryfail, 7, SLZ_KTR_STRING, SLZ_KTR_ARGS);
82 KTR_INFO(KTR_SERIALIZER, slz, tryok, 8, SLZ_KTR_STRING, SLZ_KTR_ARGS);
83 KTR_INFO(KTR_SERIALIZER, slz, enter_end, 9, SLZ_KTR_STRING, SLZ_KTR_ARGS);
84 KTR_INFO(KTR_SERIALIZER, slz, exit_beg, 10, SLZ_KTR_STRING, SLZ_KTR_ARGS);
85 KTR_INFO(KTR_SERIALIZER, slz, adapt_beg, 11, SLZ_KTR_STRING, SLZ_KTR_ARGS);
86 KTR_INFO(KTR_SERIALIZER, slz, adapt_end, 12, SLZ_KTR_STRING, SLZ_KTR_ARGS);
87 KTR_INFO(KTR_SERIALIZER, slz, adapt_spinend, 13, "slz=%p try=%d",
88 lwkt_serialize_t slz, int try);
89 KTR_INFO(KTR_SERIALIZER, slz, adapt_sleepb, 14, SLZ_KTR_STRING, SLZ_KTR_ARGS);
90 KTR_INFO(KTR_SERIALIZER, slz, adapt_sleepe, 15, SLZ_KTR_STRING, SLZ_KTR_ARGS);
92 #define logslz(name, slz) KTR_LOG(slz_ ## name, slz)
93 #define logslz_spinend(slz, try) KTR_LOG(slz_adapt_spinend, slz, try)
95 static void lwkt_serialize_sleep(void *info);
96 static void lwkt_serialize_wakeup(void *info);
99 lwkt_serialize_init(lwkt_serialize_t s)
101 atomic_intr_init(&s->interlock);
103 s->last_td = (void *)-4;
108 lwkt_serialize_enter(lwkt_serialize_t s)
110 ASSERT_NOT_SERIALIZED(s);
112 logslz(enter_beg, s);
113 atomic_intr_cond_enter(&s->interlock, lwkt_serialize_sleep, s);
114 logslz(enter_end, s);
116 s->last_td = curthread;
121 * Returns non-zero on success
124 lwkt_serialize_try(lwkt_serialize_t s)
128 ASSERT_NOT_SERIALIZED(s);
131 if ((error = atomic_intr_cond_try(&s->interlock)) == 0) {
133 s->last_td = curthread;
143 lwkt_serialize_exit(lwkt_serialize_t s)
145 ASSERT_SERIALIZED(s);
147 s->last_td = (void *)-2;
150 atomic_intr_cond_exit(&s->interlock, lwkt_serialize_wakeup, s);
155 * Interrupt handler disablement support, used by drivers. Non-stackable
159 lwkt_serialize_handler_disable(lwkt_serialize_t s)
161 atomic_intr_handler_disable(&s->interlock);
165 lwkt_serialize_handler_enable(lwkt_serialize_t s)
167 atomic_intr_handler_enable(&s->interlock);
171 lwkt_serialize_handler_call(lwkt_serialize_t s, void (*func)(void *, void *),
172 void *arg, void *frame)
175 * note: a return value of 0 indicates that the interrupt handler is
178 if (atomic_intr_handler_is_enabled(&s->interlock) == 0) {
179 logslz(enter_beg, s);
180 atomic_intr_cond_enter(&s->interlock, lwkt_serialize_sleep, s);
181 logslz(enter_end, s);
183 s->last_td = curthread;
185 if (atomic_intr_handler_is_enabled(&s->interlock) == 0)
188 ASSERT_SERIALIZED(s);
190 s->last_td = (void *)-2;
193 atomic_intr_cond_exit(&s->interlock, lwkt_serialize_wakeup, s);
199 * Similar to handler_call but does not block. Returns 0 on success,
203 lwkt_serialize_handler_try(lwkt_serialize_t s, void (*func)(void *, void *),
204 void *arg, void *frame)
207 * note: a return value of 0 indicates that the interrupt handler is
210 if (atomic_intr_handler_is_enabled(&s->interlock) == 0) {
212 if (atomic_intr_cond_try(&s->interlock) == 0) {
214 s->last_td = curthread;
220 ASSERT_SERIALIZED(s);
222 s->last_td = (void *)-2;
225 atomic_intr_cond_exit(&s->interlock, lwkt_serialize_wakeup, s);
238 * It is possible to race an interrupt which acquires and releases the
239 * bit, then calls wakeup before we actually go to sleep, so we
240 * need to check that the interlock is still acquired from within
241 * a critical section prior to sleeping.
244 lwkt_serialize_sleep(void *info)
246 lwkt_serialize_t s = info;
248 tsleep_interlock(s, 0);
249 if (atomic_intr_cond_test(&s->interlock) != 0) {
250 logslz(sleep_beg, s);
251 tsleep(s, PINTERLOCKED, "slize", 0);
252 logslz(sleep_end, s);
257 lwkt_serialize_adaptive_enter(lwkt_serialize_t s)
261 ASSERT_NOT_SERIALIZED(s);
262 logslz(adapt_beg, s);
264 if (atomic_intr_cond_try(&s->interlock) == 0) {
266 s->last_td = curthread;
268 logslz(adapt_end, s);
274 * Spinning a little bit, before going to sleep
276 * See the comment before kern/kern_spinlock.c
277 * _spin_lock_contested() about why atomic_intr_cond_test()
278 * is called first. atomic_intr_cond_test() contains
279 * _no_ MPLOCKED intruction.
281 for (try = SLZ_ADAPTIVE_SPINMAX; try; --try) {
282 if (atomic_intr_cond_test(&s->interlock) == 0 &&
283 atomic_intr_cond_try(&s->interlock) == 0) {
285 s->last_td = curthread;
287 logslz_spinend(s, try);
292 atomic_intr_cond_inc(&s->interlock);
294 tsleep_interlock(s, 0);
295 if (atomic_intr_cond_try(&s->interlock) == 0) {
296 atomic_intr_cond_dec(&s->interlock);
298 s->last_td = curthread;
300 logslz_spinend(s, 0);
303 logslz(adapt_sleepb, s);
304 tsleep(s, PINTERLOCKED, "aslize", 0);
305 logslz(adapt_sleepe, s);
307 atomic_intr_cond_dec(&s->interlock);
313 lwkt_serialize_wakeup(void *info)
315 logslz(wakeup_beg, info);
317 logslz(wakeup_end, info);