sys/kern/lwkt_serialize.c

   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 }