2 * lwp.c -- lightweight process creation, destruction and manipulation.
3 * Copyright (C) 1991-3 Stephen Crane.
5 * This library is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU Library General Public
7 * License as published by the Free Software Foundation; either
8 * version 2 of the License, or (at your option) any later version.
10 * This library is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * Library General Public License for more details.
15 * You should have received a copy of the GNU Library General Public
16 * License along with this library; if not, write to the Free
17 * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
19 * author: Stephen Crane, (jsc@doc.ic.ac.uk), Department of Computing,
20 * Imperial College of Science, Technology and Medicine, 180 Queen's
21 * Gate, London SW7 2BZ, England.
32 #include "prototypes.h"
34 #if defined(_EMPTH_LWP)
36 struct lwpQueue LwpSchedQ[LWP_MAX_PRIO], LwpDeadQ;
38 struct lwpProc *LwpCurrent = NULL;
40 int LwpMaxpri = 0; /* maximum priority so far */
41 int LwpStackGrowsDown;
43 static sigset_t oldmask;
45 static void lwpStackCheckInit(struct lwpProc *newp);
46 static void lwpStackCheck(struct lwpProc *newp);
47 static void lwpStackCheckUsed(struct lwpProc *newp);
49 /* check stack direction */
59 * lwpReschedule -- schedule another process. we also check for dead
60 * processes here and free them.
65 static int lcount = LCOUNT;
66 static struct lwpProc *nextp;
68 static sigset_t tmask;
70 if (LwpCurrent && (LwpCurrent->flags & LWP_STACKCHECK)) {
71 lwpStackCheck(LwpCurrent);
74 int p = lwpSetPriority(LWP_MAX_PRIO - 1);
76 sigprocmask(SIG_SETMASK, &oldmask, &tmask);
77 sigprocmask(SIG_SETMASK, &tmask, &oldmask);
81 /* destroy dead threads */
82 lwpStatus(LwpCurrent, "Cleaning dead queue");
83 while (NULL != (nextp = lwpGetFirst(&LwpDeadQ))) {
84 if (nextp == LwpCurrent) {
85 lwpStatus(nextp, "OOOPS, we are running already dead thread");
89 lwpStatus(LwpCurrent, "Destroying done");
92 for (i = LwpMaxpri + 1; i--;) {
93 while (NULL != (nextp = lwpGetFirst(&LwpSchedQ[i]))) {
96 /* clean up after dead bodies */
97 lwpStatus(nextp, "got a dead body");
98 if (nextp == LwpCurrent) {
99 lwpStatus(nextp, "we are in it -- will bury later");
100 lwpAddTail(&LwpDeadQ, nextp);
109 if (LwpCurrent == 0 && nextp == 0) {
110 fprintf(stderr, "No processes to run!\n");
113 if (LwpCurrent != nextp) {
114 struct lwpProc *oldp = LwpCurrent;
116 lwpStatus(oldp, "switch out");
118 *LwpContextPtr = nextp->ud;
119 lwpSwitchContext(oldp, nextp);
120 lwpStatus(nextp, "switch in %d", nextp->pri);
125 * lwpEntryPoint -- process entry point.
133 sigaddset(&set, SIGALRM);
134 sigprocmask(SIG_SETMASK, &set, &oldmask);
135 *LwpContextPtr = LwpCurrent->ud;
137 lwpStatus(LwpCurrent, "starting at entry point");
138 (*LwpCurrent->entry)(LwpCurrent->ud);
143 * lwpCreate -- create a process.
146 lwpCreate(int priority, void (*entry)(void *), int stacksz, int flags, char *name, char *desc, int argc, char **argv, void *ud)
148 struct lwpProc *newp;
150 if (!(newp = malloc(sizeof(struct lwpProc))))
153 newp->name = strdup(name);
154 newp->desc = strdup(desc);
160 if (LWP_MAX_PRIO <= priority)
161 priority = LWP_MAX_PRIO - 1;
162 if (LwpMaxpri < (newp->pri = priority))
163 LwpMaxpri = priority;
164 if (lwpNewContext(newp, stacksz) < 0) {
170 lwpStatus(newp, "creating process structure %p (sbtm %p)",
172 if (flags & LWP_STACKCHECK)
173 lwpStackCheckInit(newp);
175 lwpReady(LwpCurrent);
181 lwpDestroy(struct lwpProc *proc)
183 if (proc->flags & LWP_STACKCHECK) {
184 lwpStackCheckUsed(proc);
187 lwpStatus(proc, "destroying sbtm: %p", proc->sbtm);
195 * lwpReady -- put process on ready queue. if null, assume current.
198 lwpReady(struct lwpProc *p)
202 lwpStatus(p, "added to run queue");
203 lwpAddTail(&LwpSchedQ[p->pri], p);
210 lwpGetUD(struct lwpProc *p)
221 lwpSetUD(struct lwpProc *p, char *ud)
232 lwpSetDesc(struct lwpProc *p, char *name, char *desc)
238 p->name = strdup(name);
239 p->desc = strdup(desc);
243 * lwpYield -- yield the processor to another thread.
248 lwpStatus(LwpCurrent, "yielding control");
249 lwpReady(LwpCurrent);
254 * cause the current process to be scheduled for deletion.
259 lwpStatus(LwpCurrent, "marking self as dead");
260 LwpCurrent->dead = 1;
265 * mark another process as dead, so it will never be rescheduled.
266 * remove any lingering FD action
269 lwpTerminate(struct lwpProc *p)
271 lwpStatus(p, "terminating process");
278 * set the thread's priority, returning the old.
279 * if the new priority is lower than the old, we reschedule.
282 lwpSetPriority(int new)
284 int old = LwpCurrent->pri;
286 if (LWP_MAX_PRIO <= new)
287 new = LWP_MAX_PRIO - 1;
290 LwpCurrent->pri = new;
291 lwpStatus(LwpCurrent, "resetting priority (%d -> %d)", old, new);
298 * initialise the coroutine structures
301 lwpInitSystem(int pri, char **ctxptr, int flags)
304 int i, *stack, marker;
307 LwpContextPtr = ctxptr;
310 /* *LwpContextPtr = 0; */
311 LwpStackGrowsDown = growsdown(&marker);
312 if (!(LwpCurrent = calloc(1, sizeof(struct lwpProc))))
314 if (!(stack = malloc(64)))
316 if (LWP_MAX_PRIO <= pri)
317 pri = LWP_MAX_PRIO - 1;
320 LwpCurrent->next = 0;
321 LwpCurrent->sbtm = stack; /* dummy stack for "main" */
322 LwpCurrent->pri = pri;
323 LwpCurrent->dead = 0;
324 LwpCurrent->flags = flags & ~LWP_STACKCHECK;
325 LwpCurrent->name = "Main";
326 for (i = LWP_MAX_PRIO, q = LwpSchedQ; i--; q++)
327 q->head = q->tail = 0;
328 LwpDeadQ.head = LwpDeadQ.tail = 0;
329 /* must be lower in priority than us for this to work right */
330 sel = lwpCreate(0, lwpSelect, 16384, flags, "EventHandler",
331 "Select (main loop) Event Handler", 0, 0, 0);
338 * Initialize the entire stack (including both redzones) with the stack
339 * check mark. Thus, we can get some indication of how much stack was
343 lwpStackCheckInit(struct lwpProc *newp)
346 int *lim = (int *)((char *)newp->sbtm + newp->size);
348 for (p = newp->sbtm; p < lim; p++)
354 * Check if the thread has overflowed/underflowed its stack.
355 * Should that happen, abort the process, as we cannot recover.
358 lwpStackCheck(struct lwpProc *newp)
360 int *btm = (int *)(newp->ustack - LWP_REDZONE);
361 int *top = (int *)(newp->ustack + newp->usize + LWP_REDZONE);
362 int n = LWP_REDZONE / sizeof(int);
363 int i, lo_clean, hi_clean, overflow, underflow;
365 for (i = 0; i < n && btm[i] == LWP_CHECKMARK; i++) ;
368 for (i = 1; i <= n && top[-i] == LWP_CHECKMARK; i++) ;
371 if (LwpStackGrowsDown) {
372 overflow = n - lo_clean;
373 underflow = n - hi_clean;
375 overflow = n - hi_clean;
376 underflow = n - lo_clean;
379 logerror("Thread %s stack overflow %d bytes",
380 newp->name, overflow * (int)sizeof(int));
382 logerror("Thread %s stack underflow %d bytes",
383 newp->name, underflow * (int)sizeof(int));
384 if (overflow || underflow)
390 * Figure out how much stack was used by this thread.
393 lwpStackCheckUsed(struct lwpProc *newp)
395 int *base = (int *)newp->ustack;
396 int *lim = (int *)(newp->ustack + newp->usize);
397 int total = (lim + 1 - base) * sizeof(int);
400 if (LwpStackGrowsDown) {
401 for (p = base; p < lim && *p == LWP_CHECKMARK; ++p) ;
402 used = (lim - p) * sizeof(int);
404 for (p = lim - 1; p >= base && *p == LWP_CHECKMARK; --p) ;
405 used = (p - base + 1) * sizeof(int);
407 lwpStatus(newp, "Thread stack %d used, %d left, %d total",
408 used, total - used, total);