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
34 * $DragonFly: src/sys/kern/lwkt_serialize.c,v 1.9 2005/12/01 18:34:09 dillon Exp $
37 * This API provides a fast locked-bus-cycle-based serializer. It's
38 * basically a low level NON-RECURSIVE exclusive lock that can be held across
39 * a blocking condition. It is NOT a mutex.
41 * This serializer is primarily designed for low level situations and
42 * interrupt/device interaction. There are two primary facilities. First,
43 * the serializer facility itself. Second, an integrated interrupt handler
44 * disablement facility.
47 #include <sys/param.h>
48 #include <sys/systm.h>
49 #include <sys/kernel.h>
51 #include <sys/rtprio.h>
52 #include <sys/queue.h>
53 #include <sys/thread2.h>
54 #include <sys/serialize.h>
55 #include <sys/sysctl.h>
56 #include <sys/kthread.h>
57 #include <machine/cpu.h>
61 static void lwkt_serialize_sleep(void *info
);
62 static void lwkt_serialize_wakeup(void *info
);
65 lwkt_serialize_init(lwkt_serialize_t s
)
67 atomic_intr_init(&s
->interlock
);
69 s
->last_td
= (void *)-4;
74 lwkt_serialize_enter(lwkt_serialize_t s
)
77 KKASSERT(s
->last_td
!= curthread
);
79 atomic_intr_cond_enter(&s
->interlock
, lwkt_serialize_sleep
, s
);
81 s
->last_td
= curthread
;
86 * Returns non-zero on success
89 lwkt_serialize_try(lwkt_serialize_t s
)
94 KKASSERT(s
->last_td
!= curthread
);
96 if ((error
= atomic_intr_cond_try(&s
->interlock
)) == 0) {
98 s
->last_td
= curthread
;
106 lwkt_serialize_exit(lwkt_serialize_t s
)
109 KKASSERT(s
->last_td
== curthread
);
110 s
->last_td
= (void *)-2;
112 atomic_intr_cond_exit(&s
->interlock
, lwkt_serialize_wakeup
, s
);
116 * Interrupt handler disablement support, used by drivers. Non-stackable
120 lwkt_serialize_handler_disable(lwkt_serialize_t s
)
122 atomic_intr_handler_disable(&s
->interlock
);
126 lwkt_serialize_handler_enable(lwkt_serialize_t s
)
128 atomic_intr_handler_enable(&s
->interlock
);
132 lwkt_serialize_handler_call(lwkt_serialize_t s
, void (*func
)(void *, void *),
133 void *arg
, void *frame
)
136 * note: a return value of 0 indicates that the interrupt handler is
139 if (atomic_intr_handler_is_enabled(&s
->interlock
) == 0) {
140 atomic_intr_cond_enter(&s
->interlock
, lwkt_serialize_sleep
, s
);
142 s
->last_td
= curthread
;
144 if (atomic_intr_handler_is_enabled(&s
->interlock
) == 0)
147 KKASSERT(s
->last_td
== curthread
);
148 s
->last_td
= (void *)-2;
150 atomic_intr_cond_exit(&s
->interlock
, lwkt_serialize_wakeup
, s
);
155 * Similar to handler_call but does not block. Returns 0 on success,
159 lwkt_serialize_handler_try(lwkt_serialize_t s
, void (*func
)(void *, void *),
160 void *arg
, void *frame
)
163 * note: a return value of 0 indicates that the interrupt handler is
166 if (atomic_intr_handler_is_enabled(&s
->interlock
) == 0) {
167 if (atomic_intr_cond_try(&s
->interlock
) == 0) {
169 s
->last_td
= curthread
;
173 KKASSERT(s
->last_td
== curthread
);
174 s
->last_td
= (void *)-2;
176 atomic_intr_cond_exit(&s
->interlock
, lwkt_serialize_wakeup
, s
);
187 * It is possible to race an interrupt which acquires and releases the
188 * bit, then calls wakeup before we actually go to sleep, so we
189 * need to check that the interlock is still acquired from within
190 * a critical section prior to sleeping.
193 lwkt_serialize_sleep(void *info
)
195 lwkt_serialize_t s
= info
;
198 if (atomic_intr_cond_test(&s
->interlock
) != 0)
199 tsleep(s
, 0, "slize", 0);
204 lwkt_serialize_wakeup(void *info
)