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/serialize.h>
52 #include <sys/sysctl.h>
54 #include <sys/kthread.h>
55 #include <machine/cpu.h>
56 #include <machine/cpufunc.h>
57 #include <machine/specialreg.h>
58 #include <machine/clock.h>
61 #ifndef SLZ_ADAPTIVE_SPINMAX
62 #define SLZ_ADAPTIVE_SPINMAX 4096
65 #define SLZ_KTR_STRING "slz=%p"
66 #define SLZ_KTR_ARGS lwkt_serialize_t slz
68 #ifndef KTR_SERIALIZER
69 #define KTR_SERIALIZER KTR_ALL
73 KTR_INFO(KTR_SERIALIZER
, slz
, enter_beg
, 0, SLZ_KTR_STRING
, SLZ_KTR_ARGS
);
74 KTR_INFO(KTR_SERIALIZER
, slz
, sleep_beg
, 1, SLZ_KTR_STRING
, SLZ_KTR_ARGS
);
75 KTR_INFO(KTR_SERIALIZER
, slz
, sleep_end
, 2, SLZ_KTR_STRING
, SLZ_KTR_ARGS
);
76 KTR_INFO(KTR_SERIALIZER
, slz
, exit_end
, 3, SLZ_KTR_STRING
, SLZ_KTR_ARGS
);
77 KTR_INFO(KTR_SERIALIZER
, slz
, wakeup_beg
, 4, SLZ_KTR_STRING
, SLZ_KTR_ARGS
);
78 KTR_INFO(KTR_SERIALIZER
, slz
, wakeup_end
, 5, SLZ_KTR_STRING
, SLZ_KTR_ARGS
);
79 KTR_INFO(KTR_SERIALIZER
, slz
, try, 6, SLZ_KTR_STRING
, SLZ_KTR_ARGS
);
80 KTR_INFO(KTR_SERIALIZER
, slz
, tryfail
, 7, SLZ_KTR_STRING
, SLZ_KTR_ARGS
);
81 KTR_INFO(KTR_SERIALIZER
, slz
, tryok
, 8, SLZ_KTR_STRING
, SLZ_KTR_ARGS
);
82 KTR_INFO(KTR_SERIALIZER
, slz
, enter_end
, 9, SLZ_KTR_STRING
, SLZ_KTR_ARGS
);
83 KTR_INFO(KTR_SERIALIZER
, slz
, exit_beg
, 10, SLZ_KTR_STRING
, SLZ_KTR_ARGS
);
84 KTR_INFO(KTR_SERIALIZER
, slz
, adapt_beg
, 11, SLZ_KTR_STRING
, SLZ_KTR_ARGS
);
85 KTR_INFO(KTR_SERIALIZER
, slz
, adapt_end
, 12, SLZ_KTR_STRING
, SLZ_KTR_ARGS
);
86 KTR_INFO(KTR_SERIALIZER
, slz
, adapt_spinend
, 13, "slz=%p try=%d",
87 lwkt_serialize_t slz
, int try);
88 KTR_INFO(KTR_SERIALIZER
, slz
, adapt_sleepb
, 14, SLZ_KTR_STRING
, SLZ_KTR_ARGS
);
89 KTR_INFO(KTR_SERIALIZER
, slz
, adapt_sleepe
, 15, SLZ_KTR_STRING
, SLZ_KTR_ARGS
);
91 #define logslz(name, slz) KTR_LOG(slz_ ## name, slz)
92 #define logslz_spinend(slz, try) KTR_LOG(slz_adapt_spinend, slz, try)
94 static void lwkt_serialize_sleep(void *info
);
95 static void lwkt_serialize_wakeup(void *info
);
98 lwkt_serialize_init(lwkt_serialize_t s
)
100 atomic_intr_init(&s
->interlock
);
101 s
->last_td
= (void *)-4;
105 lwkt_serialize_enter(lwkt_serialize_t s
)
107 ASSERT_NOT_SERIALIZED(s
);
109 logslz(enter_beg
, s
);
110 atomic_intr_cond_enter(&s
->interlock
, lwkt_serialize_sleep
, s
);
111 logslz(enter_end
, s
);
112 s
->last_td
= curthread
;
116 * Returns non-zero on success
119 lwkt_serialize_try(lwkt_serialize_t s
)
123 ASSERT_NOT_SERIALIZED(s
);
126 if ((error
= atomic_intr_cond_try(&s
->interlock
)) == 0) {
127 s
->last_td
= curthread
;
136 lwkt_serialize_exit(lwkt_serialize_t s
)
138 ASSERT_SERIALIZED(s
);
139 s
->last_td
= (void *)-2;
141 atomic_intr_cond_exit(&s
->interlock
, lwkt_serialize_wakeup
, s
);
146 * Interrupt handler disablement support, used by drivers. Non-stackable
150 lwkt_serialize_handler_disable(lwkt_serialize_t s
)
152 atomic_intr_handler_disable(&s
->interlock
);
156 lwkt_serialize_handler_enable(lwkt_serialize_t s
)
158 atomic_intr_handler_enable(&s
->interlock
);
162 lwkt_serialize_handler_call(lwkt_serialize_t s
, void (*func
)(void *, void *),
163 void *arg
, void *frame
)
166 * note: a return value of 0 indicates that the interrupt handler is
169 if (atomic_intr_handler_is_enabled(&s
->interlock
) == 0) {
170 logslz(enter_beg
, s
);
171 atomic_intr_cond_enter(&s
->interlock
, lwkt_serialize_sleep
, s
);
172 logslz(enter_end
, s
);
173 s
->last_td
= curthread
;
174 if (atomic_intr_handler_is_enabled(&s
->interlock
) == 0)
177 ASSERT_SERIALIZED(s
);
178 s
->last_td
= (void *)-2;
180 atomic_intr_cond_exit(&s
->interlock
, lwkt_serialize_wakeup
, s
);
186 * Similar to handler_call but does not block. Returns 0 on success,
190 lwkt_serialize_handler_try(lwkt_serialize_t s
, void (*func
)(void *, void *),
191 void *arg
, void *frame
)
194 * note: a return value of 0 indicates that the interrupt handler is
197 if (atomic_intr_handler_is_enabled(&s
->interlock
) == 0) {
199 if (atomic_intr_cond_try(&s
->interlock
) == 0) {
200 s
->last_td
= curthread
;
205 ASSERT_SERIALIZED(s
);
206 s
->last_td
= (void *)-2;
208 atomic_intr_cond_exit(&s
->interlock
, lwkt_serialize_wakeup
, s
);
221 * It is possible to race an interrupt which acquires and releases the
222 * bit, then calls wakeup before we actually go to sleep, so we
223 * need to check that the interlock is still acquired from within
224 * a critical section prior to sleeping.
227 lwkt_serialize_sleep(void *info
)
229 lwkt_serialize_t s
= info
;
231 tsleep_interlock(s
, 0);
232 if (atomic_intr_cond_test(&s
->interlock
) != 0) {
233 logslz(sleep_beg
, s
);
234 tsleep(s
, PINTERLOCKED
, "slize", 0);
235 logslz(sleep_end
, s
);
240 lwkt_serialize_adaptive_enter(lwkt_serialize_t s
)
244 ASSERT_NOT_SERIALIZED(s
);
245 logslz(adapt_beg
, s
);
247 if (atomic_intr_cond_try(&s
->interlock
) == 0) {
248 s
->last_td
= curthread
;
249 logslz(adapt_end
, s
);
255 * Spinning a little bit, before going to sleep
257 * See the comment before kern/kern_spinlock.c
258 * _spin_lock_contested() about why atomic_intr_cond_test()
259 * is called first. atomic_intr_cond_test() contains
260 * _no_ MPLOCKED intruction.
262 for (try = SLZ_ADAPTIVE_SPINMAX
; try; --try) {
263 if (atomic_intr_cond_test(&s
->interlock
) == 0 &&
264 atomic_intr_cond_try(&s
->interlock
) == 0) {
265 s
->last_td
= curthread
;
266 logslz_spinend(s
, try);
271 atomic_intr_cond_inc(&s
->interlock
);
273 tsleep_interlock(s
, 0);
274 if (atomic_intr_cond_try(&s
->interlock
) == 0) {
275 atomic_intr_cond_dec(&s
->interlock
);
276 s
->last_td
= curthread
;
277 logslz_spinend(s
, 0);
280 logslz(adapt_sleepb
, s
);
281 tsleep(s
, PINTERLOCKED
, "aslize", 0);
282 logslz(adapt_sleepe
, s
);
284 atomic_intr_cond_dec(&s
->interlock
);
290 lwkt_serialize_wakeup(void *info
)
292 logslz(wakeup_beg
, info
);
294 logslz(wakeup_end
, info
);