1 /* 2 * $Id: sched.c,v 5.2 90/06/23 22:19:58 jsp Rel $ 3 * 4 * Copyright (c) 1990 Jan-Simon Pendry 5 * Copyright (c) 1990 Imperial College of Science, Technology & Medicine 6 * Copyright (c) 1990 The Regents of the University of California. 7 * All rights reserved. 8 * 9 * This code is derived from software contributed to Berkeley by 10 * Jan-Simon Pendry at Imperial College, London. 11 * 12 * %sccs.include.redist.c% 13 * 14 * @(#)sched.c 5.1 (Berkeley) 06/29/90 15 */ 16 17 /* 18 * Process scheduler 19 */ 20 21 #include "am.h" 22 #include <sys/signal.h> 23 #include WAIT 24 #include <setjmp.h> 25 extern jmp_buf select_intr; 26 extern int select_intr_valid; 27 28 typedef struct pjob pjob; 29 struct pjob { 30 qelem hdr; /* Linked list */ 31 int pid; /* Process ID of job */ 32 cb_fun cb_fun; /* Callback function */ 33 voidp cb_closure; /* Closure for callback */ 34 union wait w; /* Status filled in by sigchld */ 35 voidp wchan; /* Wait channel */ 36 }; 37 38 extern qelem proc_list_head; 39 qelem proc_list_head = { &proc_list_head, &proc_list_head }; 40 extern qelem proc_wait_list; 41 qelem proc_wait_list = { &proc_wait_list, &proc_wait_list }; 42 43 int task_notify_todo; 44 45 void ins_que(elem, pred) 46 qelem *elem, *pred; 47 { 48 qelem *p = pred->q_forw; 49 elem->q_back = pred; 50 elem->q_forw = p; 51 pred->q_forw = elem; 52 p->q_back = elem; 53 } 54 55 void rem_que(elem) 56 qelem *elem; 57 { 58 qelem *p = elem->q_forw; 59 qelem *p2 = elem->q_back; 60 p2->q_forw = p; 61 p->q_back = p2; 62 } 63 64 static pjob *sched_job(cf, ca) 65 cb_fun cf; 66 voidp ca; 67 { 68 pjob *p = ALLOC(pjob); 69 70 p->cb_fun = cf; 71 p->cb_closure = ca; 72 73 /* 74 * Now place on wait queue 75 */ 76 ins_que(&p->hdr, &proc_wait_list); 77 78 return p; 79 } 80 81 void run_task(tf, ta, cf, ca) 82 task_fun tf; 83 voidp ta; 84 cb_fun cf; 85 voidp ca; 86 { 87 pjob *p = sched_job(cf, ca); 88 int mask; 89 90 p->wchan = (voidp) p; 91 92 mask = sigblock(sigmask(SIGCHLD)); 93 94 if (p->pid = background()) { 95 sigsetmask(mask); 96 return; 97 } 98 99 exit((*tf)(ta)); 100 /* firewall... */ 101 abort(); 102 } 103 104 /* 105 * Schedule a task to be run when woken up 106 */ 107 void sched_task(cf, ca, wchan) 108 cb_fun cf; 109 voidp ca; 110 voidp wchan; 111 { 112 /* 113 * Allocate a new task 114 */ 115 pjob *p = sched_job(cf, ca); 116 #ifdef DEBUG 117 /*dlog("sleep(%#x)", wchan);*/ 118 #endif /* DEBUG */ 119 p->wchan = wchan; 120 p->pid = 0; 121 bzero((voidp) &p->w, sizeof(p->w)); 122 } 123 124 static void wakeupjob(p) 125 pjob *p; 126 { 127 rem_que(&p->hdr); 128 ins_que(&p->hdr, &proc_list_head); 129 task_notify_todo++; 130 } 131 132 void wakeup(wchan) 133 voidp wchan; 134 { 135 pjob *p, *p2; 136 137 if (!foreground) 138 return; 139 140 #ifdef DEBUG 141 /*dlog("wakeup(%#x)", wchan);*/ 142 #endif /* DEBUG */ 143 /* 144 * Can't user ITER() here because 145 * wakeupjob() juggles the list. 146 */ 147 for (p = FIRST(pjob, &proc_wait_list); 148 p2 = NEXT(pjob, p), p != HEAD(pjob, &proc_wait_list); 149 p = p2) { 150 if (p->wchan == wchan) 151 wakeupjob(p); 152 } 153 } 154 155 void wakeup_task(rc, term, cl) 156 int rc; 157 int term; 158 voidp cl; 159 { 160 wakeup(cl); 161 } 162 163 /*ARGSUSED*/ 164 165 void sigchld(sig) 166 int sig; 167 { 168 union wait w; 169 int pid; 170 171 #ifdef SYS5_SIGNALS 172 if ((pid = wait(&w)) > 0) { 173 #else 174 while ((pid = wait3(&w, WNOHANG, (union wait *) 0)) > 0) { 175 #endif /* SYS5_SIGNALS */ 176 pjob *p, *p2; 177 178 if (WIFSIGNALED(w)) 179 plog(XLOG_ERROR, "Process %d exited with signal %d", 180 pid, w.w_termsig); 181 #ifdef DEBUG 182 else 183 dlog("Process %d exited with status %d", 184 pid, w.w_retcode); 185 #endif /* DEBUG */ 186 187 for (p = FIRST(pjob, &proc_wait_list); 188 p2 = NEXT(pjob, p), p != HEAD(pjob, &proc_wait_list); 189 p = p2) { 190 if (p->pid == pid) { 191 p->w = w; 192 wakeupjob(p); 193 break; 194 } 195 } 196 197 #ifdef DEBUG 198 if (p) ; else dlog("can't locate task block for pid %d", pid); 199 #endif /* DEBUG */ 200 } 201 202 #ifdef SYS5_SIGNALS 203 signal(sig, sigchld); 204 #endif /* SYS5_SIGNALS */ 205 if (select_intr_valid) 206 longjmp(select_intr, sigchld); 207 } 208 209 /* 210 * Run any pending tasks. 211 * This must be called with SIGCHLD disabled 212 */ 213 void task_notify(P_void) 214 { 215 /* 216 * Keep taking the first item off the list and processing it. 217 * 218 * Done this way because the the callback can, quite reasonably, 219 * queue a new task, so no local reference into the list can be 220 * held here. 221 */ 222 while (FIRST(pjob, &proc_list_head) != HEAD(pjob, &proc_list_head)) { 223 pjob *p = FIRST(pjob, &proc_list_head); 224 rem_que(&p->hdr); 225 /* 226 * This job has completed 227 */ 228 --task_notify_todo; 229 230 /* 231 * Do callback if it exists 232 */ 233 if (p->cb_fun) 234 (*p->cb_fun)(p->w.w_retcode, 235 p->w.w_termsig, p->cb_closure); 236 237 free(p); 238 } 239 } 240