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 #include <sys/types.h> 28 #include <sys/param.h> 29 #include <sys/var.h> 30 #include <sys/thread.h> 31 #include <sys/cpuvar.h> 32 #include <sys/kstat.h> 33 #include <sys/uadmin.h> 34 #include <sys/systm.h> 35 #include <sys/errno.h> 36 #include <sys/cmn_err.h> 37 #include <sys/procset.h> 38 #include <sys/processor.h> 39 #include <sys/debug.h> 40 #include <sys/cyclic.h> 41 #include <sys/pool_pset.h> 42 43 /* 44 * cpu_intr_on - determine whether the CPU is participating 45 * in I/O interrupts. 46 */ 47 int 48 cpu_intr_on(cpu_t *cp) 49 { 50 ASSERT(MUTEX_HELD(&cpu_lock)); 51 return ((cp->cpu_flags & CPU_ENABLE) != 0); 52 } 53 54 /* 55 * Return the next on-line CPU handling interrupts. 56 */ 57 cpu_t * 58 cpu_intr_next(cpu_t *cp) 59 { 60 cpu_t *c; 61 62 ASSERT(MUTEX_HELD(&cpu_lock)); 63 64 c = cp->cpu_next_onln; 65 while (c != cp) { 66 if (cpu_intr_on(c)) { 67 return (c); 68 } 69 c = c->cpu_next_onln; 70 } 71 return (NULL); 72 } 73 74 /* 75 * cpu_intr_count - count how many CPUs are handling I/O interrupts. 76 */ 77 int 78 cpu_intr_count(cpu_t *cp) 79 { 80 cpu_t *c; 81 int count = 0; 82 83 ASSERT(MUTEX_HELD(&cpu_lock)); 84 c = cp; 85 do { 86 if (cpu_intr_on(c)) { 87 ++count; 88 } 89 } while ((c = c->cpu_next) != cp); 90 return (count); 91 } 92 93 /* 94 * Enable I/O interrupts on this CPU, if they are disabled. 95 */ 96 void 97 cpu_intr_enable(cpu_t *cp) 98 { 99 ASSERT(MUTEX_HELD(&cpu_lock)); 100 if (!cpu_intr_on(cp)) { 101 cpu_enable_intr(cp); 102 cpu_set_state(cp); 103 } 104 } 105 106 /* 107 * cpu_intr_disable - redirect I/O interrupts targetted at this CPU. 108 * 109 * semantics: We check the count of CPUs that are accepting 110 * interrupts, because it's stupid to take the last CPU out 111 * of I/O interrupt participation. This also permits the 112 * p_online syscall to fail gracefully in uniprocessor configurations 113 * without having to perform any special platform-specific operations. 114 */ 115 int 116 cpu_intr_disable(cpu_t *cp) 117 { 118 int e = EBUSY; 119 120 ASSERT(MUTEX_HELD(&cpu_lock)); 121 if ((cpu_intr_count(cp) > 1) && (cpu_intr_next(cp) != NULL)) { 122 if (cpu_intr_on(cp)) { 123 /* 124 * Juggle away cyclics, but don't fail if we don't 125 * manage to juggle all of them away; we want to allow 126 * CPU-bound cyclics to continue to fire on the 127 * sheltered CPU. 128 */ 129 (void) cyclic_juggle(cp); 130 e = cpu_disable_intr(cp); 131 } 132 } 133 if (e == 0) 134 cpu_set_state(cp); 135 return (e); 136 } 137