kernel/os/cpu_intr.c

   1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License, Version 1.0 only
   6  * (the "License").  You may not use this file except in compliance
   7  * with the License.
   8  *
   9  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
  10  * or http://www.opensolaris.org/os/licensing.
  11  * See the License for the specific language governing permissions
  12  * and limitations under the License.
  13  *
  14  * When distributing Covered Code, include this CDDL HEADER in each
  15  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  16  * If applicable, add the following below this CDDL HEADER, with the
  17  * fields enclosed by brackets "[]" replaced with your own identifying
  18  * information: Portions Copyright [yyyy] [name of copyright owner]
  19  *
  20  * CDDL HEADER END
  21  */
  22 /*
  23  * Copyright 2005 Sun Microsystems, Inc.  All rights reserved.
  24  * Use is subject to license terms.
  25  */
  26
  27 #pragma ident   "%Z%%M% %I%     %E% SMI"
  28
  29 #include <sys/types.h>
  30 #include <sys/param.h>
  31 #include <sys/var.h>
  32 #include <sys/thread.h>
  33 #include <sys/cpuvar.h>
  34 #include <sys/kstat.h>
  35 #include <sys/uadmin.h>
  36 #include <sys/systm.h>
  37 #include <sys/errno.h>
  38 #include <sys/cmn_err.h>
  39 #include <sys/procset.h>
  40 #include <sys/processor.h>
  41 #include <sys/debug.h>
  42 #include <sys/cyclic.h>
  43 #include <sys/pool_pset.h>
  44
  45 /*
  46  * cpu_intr_on - determine whether the CPU is participating
  47  * in I/O interrupts.
  48  */
  49 int
  50 cpu_intr_on(cpu_t *cp)
  51 {
  52         ASSERT(MUTEX_HELD(&cpu_lock));
  53         return ((cp->cpu_flags & CPU_ENABLE) != 0);
  54 }
  55
  56 /*
  57  * Return the next on-line CPU handling interrupts.
  58  */
  59 cpu_t *
  60 cpu_intr_next(cpu_t *cp)
  61 {
  62         cpu_t   *c;
  63
  64         ASSERT(MUTEX_HELD(&cpu_lock));
  65
  66         c = cp->cpu_next_onln;
  67         while (c != cp) {
  68                 if (cpu_intr_on(c)) {
  69                         return (c);
  70                 }
  71                 c = c->cpu_next_onln;
  72         }
  73         return (NULL);
  74 }
  75
  76 /*
  77  * cpu_intr_count - count how many CPUs are handling I/O interrupts.
  78  */
  79 int
  80 cpu_intr_count(cpu_t *cp)
  81 {
  82         cpu_t   *c;
  83         int     count = 0;
  84
  85         ASSERT(MUTEX_HELD(&cpu_lock));
  86         c = cp;
  87         do {
  88                 if (cpu_intr_on(c)) {
  89                         ++count;
  90                 }
  91         } while ((c = c->cpu_next) != cp);
  92         return (count);
  93 }
  94
  95 /*
  96  * Enable I/O interrupts on this CPU, if they are disabled.
  97  */
  98 void
  99 cpu_intr_enable(cpu_t *cp)
 100 {
 101         ASSERT(MUTEX_HELD(&cpu_lock));
 102         if (!cpu_intr_on(cp)) {
 103                 cpu_enable_intr(cp);
 104                 cpu_set_state(cp);
 105         }
 106 }
 107
 108 /*
 109  * cpu_intr_disable - redirect I/O interrupts targetted at this CPU.
 110  *
 111  * semantics: We check the count of CPUs that are accepting
 112  * interrupts, because it's stupid to take the last CPU out
 113  * of I/O interrupt participation. This also permits the
 114  * p_online syscall to fail gracefully in uniprocessor configurations
 115  * without having to perform any special platform-specific operations.
 116  */
 117 int
 118 cpu_intr_disable(cpu_t *cp)
 119 {
 120         int     e = EBUSY;
 121
 122         ASSERT(MUTEX_HELD(&cpu_lock));
 123         if ((cpu_intr_count(cp) > 1) && (cpu_intr_next(cp) != NULL)) {
 124                 if (cpu_intr_on(cp)) {
 125                         /*
 126                          * Juggle away cyclics, but don't fail if we don't
 127                          * manage to juggle all of them away; we want to allow
 128                          * CPU-bound cyclics to continue to fire on the
 129                          * sheltered CPU.
 130                          */
 131                         (void) cyclic_juggle(cp);
 132                         e = cpu_disable_intr(cp);
 133                 }
 134         }
 135         if (e == 0)
 136                 cpu_set_state(cp);
 137         return (e);
 138 }