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 } 139