thr_cancel.c revision 97204
1/* 2 * David Leonard <d@openbsd.org>, 1999. Public domain. 3 * $FreeBSD: head/lib/libkse/thread/thr_cancel.c 97204 2002-05-24 04:32:28Z deischen $ 4 */ 5#include <sys/errno.h> 6#include <pthread.h> 7#include "pthread_private.h" 8 9static void finish_cancellation(void *arg); 10 11__weak_reference(_pthread_cancel, pthread_cancel); 12__weak_reference(_pthread_setcancelstate, pthread_setcancelstate); 13__weak_reference(_pthread_setcanceltype, pthread_setcanceltype); 14__weak_reference(_pthread_testcancel, pthread_testcancel); 15 16int 17_pthread_cancel(pthread_t pthread) 18{ 19 int ret; 20 21 if ((ret = _find_thread(pthread)) != 0) { 22 /* NOTHING */ 23 } else if (pthread->state == PS_DEAD || pthread->state == PS_DEADLOCK 24 || (pthread->flags & PTHREAD_EXITING) != 0) { 25 ret = 0; 26 } else { 27 /* Protect the scheduling queues: */ 28 _thread_kern_sig_defer(); 29 30 if (((pthread->cancelflags & PTHREAD_CANCEL_DISABLE) != 0) || 31 (((pthread->cancelflags & PTHREAD_CANCEL_ASYNCHRONOUS) == 0) && 32 ((pthread->cancelflags & PTHREAD_AT_CANCEL_POINT) == 0))) 33 /* Just mark it for cancellation: */ 34 pthread->cancelflags |= PTHREAD_CANCELLING; 35 else { 36 /* 37 * Check if we need to kick it back into the 38 * run queue: 39 */ 40 switch (pthread->state) { 41 case PS_RUNNING: 42 /* No need to resume: */ 43 pthread->cancelflags |= PTHREAD_CANCELLING; 44 break; 45 46 case PS_SPINBLOCK: 47 case PS_FDR_WAIT: 48 case PS_FDW_WAIT: 49 case PS_POLL_WAIT: 50 case PS_SELECT_WAIT: 51 /* Remove these threads from the work queue: */ 52 if ((pthread->flags & PTHREAD_FLAGS_IN_WORKQ) 53 != 0) 54 PTHREAD_WORKQ_REMOVE(pthread); 55 /* Fall through: */ 56 case PS_SIGTHREAD: 57 case PS_SLEEP_WAIT: 58 case PS_WAIT_WAIT: 59 case PS_SIGSUSPEND: 60 case PS_SIGWAIT: 61 /* Interrupt and resume: */ 62 pthread->interrupted = 1; 63 pthread->cancelflags |= PTHREAD_CANCELLING; 64 PTHREAD_NEW_STATE(pthread,PS_RUNNING); 65 break; 66 67 case PS_JOIN: 68 /* 69 * Disconnect the thread from the joinee: 70 */ 71 if (pthread->join_status.thread != NULL) { 72 pthread->join_status.thread->joiner 73 = NULL; 74 pthread->join_status.thread = NULL; 75 } 76 pthread->cancelflags |= PTHREAD_CANCELLING; 77 PTHREAD_NEW_STATE(pthread, PS_RUNNING); 78 break; 79 80 case PS_SUSPENDED: 81 case PS_MUTEX_WAIT: 82 case PS_COND_WAIT: 83 case PS_FDLR_WAIT: 84 case PS_FDLW_WAIT: 85 case PS_FILE_WAIT: 86 /* 87 * Threads in these states may be in queues. 88 * In order to preserve queue integrity, the 89 * cancelled thread must remove itself from the 90 * queue. Mark the thread as interrupted and 91 * needing cancellation, and set the state to 92 * running. When the thread resumes, it will 93 * remove itself from the queue and call the 94 * cancellation completion routine. 95 */ 96 pthread->interrupted = 1; 97 pthread->cancelflags |= PTHREAD_CANCEL_NEEDED; 98 PTHREAD_NEW_STATE(pthread, PS_RUNNING); 99 pthread->continuation = finish_cancellation; 100 break; 101 102 case PS_DEAD: 103 case PS_DEADLOCK: 104 case PS_STATE_MAX: 105 /* Ignore - only here to silence -Wall: */ 106 break; 107 } 108 } 109 110 /* Unprotect the scheduling queues: */ 111 _thread_kern_sig_undefer(); 112 113 ret = 0; 114 } 115 return (ret); 116} 117 118int 119_pthread_setcancelstate(int state, int *oldstate) 120{ 121 struct pthread *curthread = _get_curthread(); 122 int ostate; 123 int ret; 124 125 ostate = curthread->cancelflags & PTHREAD_CANCEL_DISABLE; 126 127 switch (state) { 128 case PTHREAD_CANCEL_ENABLE: 129 if (oldstate != NULL) 130 *oldstate = ostate; 131 curthread->cancelflags &= ~PTHREAD_CANCEL_DISABLE; 132 if ((curthread->cancelflags & PTHREAD_CANCEL_ASYNCHRONOUS) != 0) 133 pthread_testcancel(); 134 ret = 0; 135 break; 136 case PTHREAD_CANCEL_DISABLE: 137 if (oldstate != NULL) 138 *oldstate = ostate; 139 curthread->cancelflags |= PTHREAD_CANCEL_DISABLE; 140 ret = 0; 141 break; 142 default: 143 ret = EINVAL; 144 } 145 146 return (ret); 147} 148 149int 150_pthread_setcanceltype(int type, int *oldtype) 151{ 152 struct pthread *curthread = _get_curthread(); 153 int otype; 154 int ret; 155 156 otype = curthread->cancelflags & PTHREAD_CANCEL_ASYNCHRONOUS; 157 switch (type) { 158 case PTHREAD_CANCEL_ASYNCHRONOUS: 159 if (oldtype != NULL) 160 *oldtype = otype; 161 curthread->cancelflags |= PTHREAD_CANCEL_ASYNCHRONOUS; 162 pthread_testcancel(); 163 ret = 0; 164 break; 165 case PTHREAD_CANCEL_DEFERRED: 166 if (oldtype != NULL) 167 *oldtype = otype; 168 curthread->cancelflags &= ~PTHREAD_CANCEL_ASYNCHRONOUS; 169 ret = 0; 170 break; 171 default: 172 ret = EINVAL; 173 } 174 175 return (ret); 176} 177 178void 179_pthread_testcancel(void) 180{ 181 struct pthread *curthread = _get_curthread(); 182 183 if (((curthread->cancelflags & PTHREAD_CANCEL_DISABLE) == 0) && 184 ((curthread->cancelflags & PTHREAD_CANCELLING) != 0) && 185 ((curthread->flags & PTHREAD_EXITING) == 0)) { 186 /* 187 * It is possible for this thread to be swapped out 188 * while performing cancellation; do not allow it 189 * to be cancelled again. 190 */ 191 curthread->cancelflags &= ~PTHREAD_CANCELLING; 192 _thread_exit_cleanup(); 193 pthread_exit(PTHREAD_CANCELED); 194 PANIC("cancel"); 195 } 196} 197 198void 199_thread_enter_cancellation_point(void) 200{ 201 struct pthread *curthread = _get_curthread(); 202 203 /* Look for a cancellation before we block: */ 204 pthread_testcancel(); 205 curthread->cancelflags |= PTHREAD_AT_CANCEL_POINT; 206} 207 208void 209_thread_leave_cancellation_point(void) 210{ 211 struct pthread *curthread = _get_curthread(); 212 213 curthread->cancelflags &= ~PTHREAD_AT_CANCEL_POINT; 214 /* Look for a cancellation after we unblock: */ 215 pthread_testcancel(); 216} 217 218static void 219finish_cancellation(void *arg) 220{ 221 struct pthread *curthread = _get_curthread(); 222 223 curthread->continuation = NULL; 224 curthread->interrupted = 0; 225 226 if ((curthread->cancelflags & PTHREAD_CANCEL_NEEDED) != 0) { 227 curthread->cancelflags &= ~PTHREAD_CANCEL_NEEDED; 228 _thread_exit_cleanup(); 229 pthread_exit(PTHREAD_CANCELED); 230 } 231} 232