1 /* 2 * Copyright (c) 2005 The DragonFly Project. All rights reserved. 3 * 4 * This code is derived from software contributed to The DragonFly Project 5 * by Matthew Dillon <dillon@backplane.com> 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 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 16 * distribution. 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. 20 * 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 32 * SUCH DAMAGE. 33 * 34 * $DragonFly: src/sys/kern/lwkt_serialize.c,v 1.12 2008/04/29 16:00:12 sephe Exp $ 35 */ 36 /* 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. 40 * 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. 45 */ 46 47 #include "opt_serializer.h" 48 49 #include <sys/param.h> 50 #include <sys/systm.h> 51 #include <sys/kernel.h> 52 #include <sys/proc.h> 53 #include <sys/rtprio.h> 54 #include <sys/queue.h> 55 #include <sys/thread2.h> 56 #include <sys/serialize.h> 57 #include <sys/sysctl.h> 58 #include <sys/ktr.h> 59 #include <sys/kthread.h> 60 #include <machine/cpu.h> 61 #include <sys/lock.h> 62 #include <sys/caps.h> 63 64 #define SLZ_KTR_STRING "slz=%p" 65 #define SLZ_KTR_ARG_SIZE (sizeof(void *)) 66 67 #ifndef KTR_SERIALIZER 68 #define KTR_SERIALIZER KTR_ALL 69 #endif 70 71 KTR_INFO_MASTER(slz); 72 KTR_INFO(KTR_SERIALIZER, slz, enter, 0, SLZ_KTR_STRING, SLZ_KTR_ARG_SIZE); 73 KTR_INFO(KTR_SERIALIZER, slz, sleep, 1, SLZ_KTR_STRING, SLZ_KTR_ARG_SIZE); 74 KTR_INFO(KTR_SERIALIZER, slz, exit, 2, SLZ_KTR_STRING, SLZ_KTR_ARG_SIZE); 75 KTR_INFO(KTR_SERIALIZER, slz, wakeup, 3, SLZ_KTR_STRING, SLZ_KTR_ARG_SIZE); 76 KTR_INFO(KTR_SERIALIZER, slz, try, 4, SLZ_KTR_STRING, SLZ_KTR_ARG_SIZE); 77 KTR_INFO(KTR_SERIALIZER, slz, tryfail, 5, SLZ_KTR_STRING, SLZ_KTR_ARG_SIZE); 78 KTR_INFO(KTR_SERIALIZER, slz, tryok, 6, SLZ_KTR_STRING, SLZ_KTR_ARG_SIZE); 79 80 #define logslz(name, slz) KTR_LOG(slz_ ## name, slz) 81 82 static void lwkt_serialize_sleep(void *info); 83 static void lwkt_serialize_wakeup(void *info); 84 85 void 86 lwkt_serialize_init(lwkt_serialize_t s) 87 { 88 atomic_intr_init(&s->interlock); 89 #ifdef INVARIANTS 90 s->last_td = (void *)-4; 91 #endif 92 s->sleep_cnt = 0; 93 s->tryfail_cnt = 0; 94 s->enter_cnt = 0; 95 s->try_cnt = 0; 96 } 97 98 void 99 lwkt_serialize_enter(lwkt_serialize_t s) 100 { 101 #ifdef INVARIANTS 102 KKASSERT(s->last_td != curthread); 103 #endif 104 logslz(enter, s); 105 atomic_intr_cond_enter(&s->interlock, lwkt_serialize_sleep, s); 106 #ifdef INVARIANTS 107 s->last_td = curthread; 108 #endif 109 #ifdef PROFILE_SERIALIZER 110 s->enter_cnt++; 111 #endif 112 } 113 114 /* 115 * Returns non-zero on success 116 */ 117 int 118 lwkt_serialize_try(lwkt_serialize_t s) 119 { 120 int error; 121 122 #ifdef INVARIANTS 123 KKASSERT(s->last_td != curthread); 124 #endif 125 #ifdef PROFILE_SERIALIZER 126 s->try_cnt++; 127 #endif 128 logslz(try, s); 129 if ((error = atomic_intr_cond_try(&s->interlock)) == 0) { 130 #ifdef INVARIANTS 131 s->last_td = curthread; 132 #endif 133 logslz(tryok, s); 134 return(1); 135 } 136 #ifdef PROFILE_SERIALIZER 137 s->tryfail_cnt++; 138 #endif 139 logslz(tryfail, s); 140 return (0); 141 } 142 143 void 144 lwkt_serialize_exit(lwkt_serialize_t s) 145 { 146 #ifdef INVARIANTS 147 KKASSERT(s->last_td == curthread); 148 s->last_td = (void *)-2; 149 #endif 150 logslz(exit, s); 151 atomic_intr_cond_exit(&s->interlock, lwkt_serialize_wakeup, s); 152 } 153 154 /* 155 * Interrupt handler disablement support, used by drivers. Non-stackable 156 * (uses bit 30). 157 */ 158 void 159 lwkt_serialize_handler_disable(lwkt_serialize_t s) 160 { 161 atomic_intr_handler_disable(&s->interlock); 162 } 163 164 void 165 lwkt_serialize_handler_enable(lwkt_serialize_t s) 166 { 167 atomic_intr_handler_enable(&s->interlock); 168 } 169 170 void 171 lwkt_serialize_handler_call(lwkt_serialize_t s, void (*func)(void *, void *), 172 void *arg, void *frame) 173 { 174 /* 175 * note: a return value of 0 indicates that the interrupt handler is 176 * enabled. 177 */ 178 if (atomic_intr_handler_is_enabled(&s->interlock) == 0) { 179 logslz(enter, s); 180 atomic_intr_cond_enter(&s->interlock, lwkt_serialize_sleep, s); 181 #ifdef INVARIANTS 182 s->last_td = curthread; 183 #endif 184 #ifdef PROFILE_SERIALIZER 185 s->enter_cnt++; 186 #endif 187 if (atomic_intr_handler_is_enabled(&s->interlock) == 0) 188 func(arg, frame); 189 #ifdef INVARIANTS 190 KKASSERT(s->last_td == curthread); 191 s->last_td = (void *)-2; 192 #endif 193 logslz(exit, s); 194 atomic_intr_cond_exit(&s->interlock, lwkt_serialize_wakeup, s); 195 } 196 } 197 198 /* 199 * Similar to handler_call but does not block. Returns 0 on success, 200 * and 1 on failure. 201 */ 202 int 203 lwkt_serialize_handler_try(lwkt_serialize_t s, void (*func)(void *, void *), 204 void *arg, void *frame) 205 { 206 /* 207 * note: a return value of 0 indicates that the interrupt handler is 208 * enabled. 209 */ 210 if (atomic_intr_handler_is_enabled(&s->interlock) == 0) { 211 #ifdef PROFILE_SERIALIZER 212 s->try_cnt++; 213 #endif 214 logslz(try, s); 215 if (atomic_intr_cond_try(&s->interlock) == 0) { 216 #ifdef INVARIANTS 217 s->last_td = curthread; 218 #endif 219 logslz(tryok, s); 220 func(arg, frame); 221 #ifdef INVARIANTS 222 KKASSERT(s->last_td == curthread); 223 s->last_td = (void *)-2; 224 #endif 225 logslz(exit, s); 226 atomic_intr_cond_exit(&s->interlock, lwkt_serialize_wakeup, s); 227 return(0); 228 } 229 } 230 #ifdef PROFILE_SERIALIZER 231 s->tryfail_cnt++; 232 #endif 233 logslz(tryfail, s); 234 return(1); 235 } 236 237 238 /* 239 * Helper functions 240 * 241 * It is possible to race an interrupt which acquires and releases the 242 * bit, then calls wakeup before we actually go to sleep, so we 243 * need to check that the interlock is still acquired from within 244 * a critical section prior to sleeping. 245 */ 246 static void 247 lwkt_serialize_sleep(void *info) 248 { 249 lwkt_serialize_t s = info; 250 crit_enter(); 251 tsleep_interlock(s); 252 if (atomic_intr_cond_test(&s->interlock) != 0) { 253 #ifdef PROFILE_SERIALIZER 254 s->sleep_cnt++; 255 #endif 256 logslz(sleep, s); 257 tsleep(s, 0, "slize", 0); 258 } 259 crit_exit(); 260 } 261 262 static void 263 lwkt_serialize_wakeup(void *info) 264 { 265 logslz(wakeup, info); 266 wakeup(info); 267 } 268