1 /* 2 * Copyright (c) 2005, David Xu <davidxu@freebsd.org> 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice unmodified, this list of conditions, and the following 10 * disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 * 26 * $FreeBSD$ 27 */ 28 29 #include <sys/param.h> 30 #include <sys/types.h> 31 #include <sys/signalvar.h> 32 #include <signal.h> 33 #include <errno.h> 34 #include <fcntl.h> 35 #include <unistd.h> 36 #include <string.h> 37 #include <pthread.h> 38 39 #include "thr_private.h" 40 41 /* #define DEBUG_SIGNAL */ 42 #ifdef DEBUG_SIGNAL 43 #define DBG_MSG stdout_debug 44 #else 45 #define DBG_MSG(x...) 46 #endif 47 48 static void 49 sigcancel_handler(int sig, siginfo_t *info, ucontext_t *ucp) 50 { 51 struct pthread *curthread = _get_curthread(); 52 53 if (curthread->cancelflags & THR_CANCEL_AT_POINT) 54 pthread_testcancel(); 55 _thr_ast(curthread); 56 } 57 58 void 59 _thr_ast(struct pthread *curthread) 60 { 61 if (!THR_IN_CRITICAL(curthread)) { 62 if (__predict_false((curthread->flags & 63 (THR_FLAGS_NEED_SUSPEND | THR_FLAGS_SUSPENDED)) 64 == THR_FLAGS_NEED_SUSPEND)) 65 _thr_suspend_check(curthread); 66 } 67 } 68 69 void 70 _thr_suspend_check(struct pthread *curthread) 71 { 72 umtx_t cycle; 73 74 /* 75 * Blocks SIGCANCEL which other threads must send. 76 */ 77 _thr_signal_block(curthread); 78 79 /* 80 * Increase critical_count, here we don't use THR_LOCK/UNLOCK 81 * because we are leaf code, we don't want to recursively call 82 * ourself. 83 */ 84 curthread->critical_count++; 85 THR_UMTX_LOCK(curthread, &(curthread)->lock); 86 while ((curthread->flags & (THR_FLAGS_NEED_SUSPEND | 87 THR_FLAGS_SUSPENDED)) == THR_FLAGS_NEED_SUSPEND) { 88 curthread->cycle++; 89 cycle = curthread->cycle; 90 91 /* Wake the thread suspending us. */ 92 _thr_umtx_wake(&curthread->cycle, INT_MAX); 93 94 /* 95 * if we are from pthread_exit, we don't want to 96 * suspend, just go and die. 97 */ 98 if (curthread->state == PS_DEAD) 99 break; 100 curthread->flags |= THR_FLAGS_SUSPENDED; 101 THR_UMTX_UNLOCK(curthread, &(curthread)->lock); 102 _thr_umtx_wait(&curthread->cycle, cycle, NULL); 103 THR_UMTX_LOCK(curthread, &(curthread)->lock); 104 curthread->flags &= ~THR_FLAGS_SUSPENDED; 105 } 106 THR_UMTX_UNLOCK(curthread, &(curthread)->lock); 107 curthread->critical_count--; 108 109 /* 110 * Unblocks SIGCANCEL, it is possible a new SIGCANCEL is ready and 111 * a new signal frame will nest us, this seems a problem because 112 * stack will grow and overflow, but because kernel will automatically 113 * mask the SIGCANCEL when delivering the signal, so we at most only 114 * have one nesting signal frame, this should be fine. 115 */ 116 _thr_signal_unblock(curthread); 117 } 118 119 void 120 _thr_signal_init(void) 121 { 122 struct sigaction act; 123 124 /* Install cancel handler. */ 125 SIGEMPTYSET(act.sa_mask); 126 act.sa_flags = SA_SIGINFO | SA_RESTART; 127 act.sa_sigaction = (__siginfohandler_t *)&sigcancel_handler; 128 __sys_sigaction(SIGCANCEL, &act, NULL); 129 } 130 131 void 132 _thr_signal_deinit(void) 133 { 134 } 135 136 __weak_reference(_sigaction, sigaction); 137 138 int 139 _sigaction(int sig, const struct sigaction * act, struct sigaction * oact) 140 { 141 /* Check if the signal number is out of range: */ 142 if (sig < 1 || sig > _SIG_MAXSIG || sig == SIGCANCEL) { 143 /* Return an invalid argument: */ 144 errno = EINVAL; 145 return (-1); 146 } 147 148 return __sys_sigaction(sig, act, oact); 149 } 150 151 __weak_reference(_sigprocmask, sigprocmask); 152 153 int 154 _sigprocmask(int how, const sigset_t *set, sigset_t *oset) 155 { 156 const sigset_t *p = set; 157 sigset_t newset; 158 159 if (how != SIG_UNBLOCK) { 160 if (set != NULL) { 161 newset = *set; 162 SIGDELSET(newset, SIGCANCEL); 163 p = &newset; 164 } 165 } 166 return (__sys_sigprocmask(how, p, oset)); 167 } 168 169 __weak_reference(_pthread_sigmask, pthread_sigmask); 170 171 int 172 _pthread_sigmask(int how, const sigset_t *set, sigset_t *oset) 173 { 174 if (_sigprocmask(how, set, oset)) 175 return (errno); 176 return (0); 177 } 178 179 __weak_reference(_sigsuspend, sigsuspend); 180 181 int 182 _sigsuspend(const sigset_t * set) 183 { 184 struct pthread *curthread = _get_curthread(); 185 sigset_t newset; 186 const sigset_t *pset; 187 int oldcancel; 188 int ret; 189 190 if (SIGISMEMBER(*set, SIGCANCEL)) { 191 newset = *set; 192 SIGDELSET(newset, SIGCANCEL); 193 pset = &newset; 194 } else 195 pset = set; 196 197 oldcancel = _thr_cancel_enter(curthread); 198 ret = __sys_sigsuspend(pset); 199 _thr_cancel_leave(curthread, oldcancel); 200 201 return (ret); 202 } 203 204 __weak_reference(__sigwait, sigwait); 205 __weak_reference(__sigtimedwait, sigtimedwait); 206 __weak_reference(__sigwaitinfo, sigwaitinfo); 207 208 int 209 __sigtimedwait(const sigset_t *set, siginfo_t *info, 210 const struct timespec * timeout) 211 { 212 struct pthread *curthread = _get_curthread(); 213 sigset_t newset; 214 const sigset_t *pset; 215 int oldcancel; 216 int ret; 217 218 if (SIGISMEMBER(*set, SIGCANCEL)) { 219 newset = *set; 220 SIGDELSET(newset, SIGCANCEL); 221 pset = &newset; 222 } else 223 pset = set; 224 oldcancel = _thr_cancel_enter(curthread); 225 ret = __sys_sigtimedwait(pset, info, timeout); 226 _thr_cancel_leave(curthread, oldcancel); 227 return (ret); 228 } 229 230 int 231 __sigwaitinfo(const sigset_t *set, siginfo_t *info) 232 { 233 struct pthread *curthread = _get_curthread(); 234 sigset_t newset; 235 const sigset_t *pset; 236 int oldcancel; 237 int ret; 238 239 if (SIGISMEMBER(*set, SIGCANCEL)) { 240 newset = *set; 241 SIGDELSET(newset, SIGCANCEL); 242 pset = &newset; 243 } else 244 pset = set; 245 246 oldcancel = _thr_cancel_enter(curthread); 247 ret = __sys_sigwaitinfo(pset, info); 248 _thr_cancel_leave(curthread, oldcancel); 249 return (ret); 250 } 251 252 int 253 __sigwait(const sigset_t *set, int *sig) 254 { 255 struct pthread *curthread = _get_curthread(); 256 sigset_t newset; 257 const sigset_t *pset; 258 int oldcancel; 259 int ret; 260 261 if (SIGISMEMBER(*set, SIGCANCEL)) { 262 newset = *set; 263 SIGDELSET(newset, SIGCANCEL); 264 pset = &newset; 265 } else 266 pset = set; 267 268 oldcancel = _thr_cancel_enter(curthread); 269 ret = __sys_sigwait(pset, sig); 270 _thr_cancel_leave(curthread, oldcancel); 271 return (ret); 272 } 273