1 8d4a3514 2004-09-17 devnull /*
  2 8d4a3514 2004-09-17 devnull  * Is nothing simple?
  3 8d4a3514 2004-09-17 devnull  *
  4 8d4a3514 2004-09-17 devnull  * We can't free the stack until we've finished executing,
  5 8d4a3514 2004-09-17 devnull  * but once we've finished executing, we can't do anything
  6 8d4a3514 2004-09-17 devnull  * at all, including call free.  So instead we keep a linked list
  7 8d4a3514 2004-09-17 devnull  * of all stacks for all processes, and every few times we try
  8 8d4a3514 2004-09-17 devnull  * to allocate a new stack we scan the current stack list for
  9 8d4a3514 2004-09-17 devnull  * dead processes and reclaim those stacks.
 10 8d4a3514 2004-09-17 devnull  */
 11 8d4a3514 2004-09-17 devnull 
 12 8d4a3514 2004-09-17 devnull #include <u.h>
 13 8d4a3514 2004-09-17 devnull #include <sys/types.h>
 14 8d4a3514 2004-09-17 devnull #include <sys/wait.h>
 15 8d4a3514 2004-09-17 devnull #include <sched.h>
 16 8d4a3514 2004-09-17 devnull #include <signal.h>
 17 8d4a3514 2004-09-17 devnull #include <errno.h>
 18 8d4a3514 2004-09-17 devnull #include <libc.h>
 19 8d4a3514 2004-09-17 devnull #include "9proc.h"
 20 8d4a3514 2004-09-17 devnull 
 21 8d4a3514 2004-09-17 devnull int fforkstacksize = 16384;
 22 8d4a3514 2004-09-17 devnull 
 23 8d4a3514 2004-09-17 devnull typedef struct Stack Stack;
 24 8d4a3514 2004-09-17 devnull struct Stack
 25 8d4a3514 2004-09-17 devnull {
 26 8d4a3514 2004-09-17 devnull 	Stack *next;
 27 8d4a3514 2004-09-17 devnull 	Stack *fnext;
 28 8d4a3514 2004-09-17 devnull 	int pid;
 29 8d4a3514 2004-09-17 devnull };
 30 8d4a3514 2004-09-17 devnull 
 31 8d4a3514 2004-09-17 devnull static Lock stacklock;
 32 8d4a3514 2004-09-17 devnull static Stack *freestacks;
 33 8d4a3514 2004-09-17 devnull static Stack *allstacks;
 34 8d4a3514 2004-09-17 devnull static int stackmallocs;
 35 8d4a3514 2004-09-17 devnull static void gc(void);
 36 8d4a3514 2004-09-17 devnull 
 37 8d4a3514 2004-09-17 devnull static void*
 38 8d4a3514 2004-09-17 devnull mallocstack(void)
 39 8d4a3514 2004-09-17 devnull {
 40 8d4a3514 2004-09-17 devnull 	Stack *p;
 41 8d4a3514 2004-09-17 devnull 
 42 8d4a3514 2004-09-17 devnull 	lock(&stacklock);
 43 8d4a3514 2004-09-17 devnull top:
 44 8d4a3514 2004-09-17 devnull 	p = freestacks;
 45 8d4a3514 2004-09-17 devnull 	if(p)
 46 8d4a3514 2004-09-17 devnull 		freestacks = p->fnext;
 47 8d4a3514 2004-09-17 devnull 	else{
 48 8d4a3514 2004-09-17 devnull 		if(stackmallocs++%1 == 0)
 49 8d4a3514 2004-09-17 devnull 			gc();
 50 8d4a3514 2004-09-17 devnull 		if(freestacks)
 51 8d4a3514 2004-09-17 devnull 			goto top;
 52 8d4a3514 2004-09-17 devnull 		p = malloc(fforkstacksize);
 53 8d4a3514 2004-09-17 devnull 		p->next = allstacks;
 54 8d4a3514 2004-09-17 devnull 		allstacks = p;
 55 8d4a3514 2004-09-17 devnull 	}
 56 8d4a3514 2004-09-17 devnull 	if(p)
 57 8d4a3514 2004-09-17 devnull 		p->pid = 1;
 58 8d4a3514 2004-09-17 devnull 	unlock(&stacklock);
 59 8d4a3514 2004-09-17 devnull 	return p;
 60 8d4a3514 2004-09-17 devnull }
 61 8d4a3514 2004-09-17 devnull 
 62 8d4a3514 2004-09-17 devnull static void
 63 8d4a3514 2004-09-17 devnull gc(void)
 64 8d4a3514 2004-09-17 devnull {
 65 8d4a3514 2004-09-17 devnull 	Stack *p;
 66 8d4a3514 2004-09-17 devnull 
 67 8d4a3514 2004-09-17 devnull 	for(p=allstacks; p; p=p->next){
 68 8d4a3514 2004-09-17 devnull 		if(p->pid > 1)
 69 8d4a3514 2004-09-17 devnull 		if(kill(p->pid, 0) < 0 && errno == ESRCH){
 70 8d4a3514 2004-09-17 devnull 			if(0) fprint(2, "reclaim stack from %d\n", p->pid);
 71 8d4a3514 2004-09-17 devnull 			p->pid = 0;
 72 8d4a3514 2004-09-17 devnull 		}
 73 8d4a3514 2004-09-17 devnull 		if(p->pid == 0){
 74 8d4a3514 2004-09-17 devnull 			p->fnext = freestacks;
 75 8d4a3514 2004-09-17 devnull 			freestacks = p;
 76 8d4a3514 2004-09-17 devnull 		}
 77 8d4a3514 2004-09-17 devnull 	}
 78 8d4a3514 2004-09-17 devnull }
 79 8d4a3514 2004-09-17 devnull 
 80 8d4a3514 2004-09-17 devnull static void
 81 8d4a3514 2004-09-17 devnull freestack(void *v)
 82 8d4a3514 2004-09-17 devnull {
 83 8d4a3514 2004-09-17 devnull 	Stack *p;
 84 8d4a3514 2004-09-17 devnull 
 85 8d4a3514 2004-09-17 devnull 	p = v;
 86 8d4a3514 2004-09-17 devnull 	if(p == nil)
 87 8d4a3514 2004-09-17 devnull 		return;
 88 8d4a3514 2004-09-17 devnull 	lock(&stacklock);
 89 8d4a3514 2004-09-17 devnull 	p->fnext = freestacks;
 90 8d4a3514 2004-09-17 devnull 	p->pid = 0;
 91 8d4a3514 2004-09-17 devnull 	freestacks = p;
 92 8d4a3514 2004-09-17 devnull 	unlock(&stacklock);
 93 8d4a3514 2004-09-17 devnull 	return;
 94 8d4a3514 2004-09-17 devnull }
 95 8d4a3514 2004-09-17 devnull 
 96 8d4a3514 2004-09-17 devnull static int
 97 8d4a3514 2004-09-17 devnull tramp(void *v)
 98 8d4a3514 2004-09-17 devnull {
 99 8d4a3514 2004-09-17 devnull 	void (*fn)(void*), *arg;
100 8d4a3514 2004-09-17 devnull 	void **v2;
101 8d4a3514 2004-09-17 devnull 	void *p;
102 8d4a3514 2004-09-17 devnull 
103 8d4a3514 2004-09-17 devnull 	_p9uproc(0);
104 8d4a3514 2004-09-17 devnull 	v2 = v;
105 8d4a3514 2004-09-17 devnull 	fn = v2[0];
106 8d4a3514 2004-09-17 devnull 	arg = v2[1];
107 8d4a3514 2004-09-17 devnull 	p = v2[2];
108 8d4a3514 2004-09-17 devnull 	free(v2);
109 8d4a3514 2004-09-17 devnull 	fn(arg);
110 8d4a3514 2004-09-17 devnull 	_exit(0);
111 8d4a3514 2004-09-17 devnull 	return 0;
112 8d4a3514 2004-09-17 devnull }
113 8d4a3514 2004-09-17 devnull 	
114 8d4a3514 2004-09-17 devnull static int
115 8d4a3514 2004-09-17 devnull trampnowait(void *v)
116 8d4a3514 2004-09-17 devnull {
117 8d4a3514 2004-09-17 devnull 	int pid;
118 8d4a3514 2004-09-17 devnull 	int cloneflag;
119 8d4a3514 2004-09-17 devnull 	void **v2;
120 8d4a3514 2004-09-17 devnull 	int *pidp;
121 8d4a3514 2004-09-17 devnull 	void *p;
122 8d4a3514 2004-09-17 devnull 
123 8d4a3514 2004-09-17 devnull 	v2 = v;
124 8d4a3514 2004-09-17 devnull 	cloneflag = (int)v2[4];
125 8d4a3514 2004-09-17 devnull 	pidp = v2[3];
126 8d4a3514 2004-09-17 devnull 	p = v2[2];
127 8d4a3514 2004-09-17 devnull 	pid = clone(tramp, p+fforkstacksize-512, cloneflag, v);
128 8d4a3514 2004-09-17 devnull 	*pidp = pid;
129 8d4a3514 2004-09-17 devnull 	_exit(0);
130 8d4a3514 2004-09-17 devnull 	return 0;
131 8d4a3514 2004-09-17 devnull }
132 8d4a3514 2004-09-17 devnull 
133 8d4a3514 2004-09-17 devnull int
134 8d4a3514 2004-09-17 devnull ffork(int flags, void (*fn)(void*), void *arg)
135 8d4a3514 2004-09-17 devnull {
136 8d4a3514 2004-09-17 devnull 	void **v;
137 8d4a3514 2004-09-17 devnull 	char *p;
138 8d4a3514 2004-09-17 devnull 	int cloneflag, pid, thepid, status, nowait;
139 8d4a3514 2004-09-17 devnull 
140 8d4a3514 2004-09-17 devnull 	_p9uproc(0);
141 8d4a3514 2004-09-17 devnull 	p = mallocstack();
142 8d4a3514 2004-09-17 devnull 	v = malloc(sizeof(void*)*5);
143 8d4a3514 2004-09-17 devnull 	if(p==nil || v==nil){
144 8d4a3514 2004-09-17 devnull 		freestack(p);
145 8d4a3514 2004-09-17 devnull 		free(v);
146 8d4a3514 2004-09-17 devnull 		return -1;
147 8d4a3514 2004-09-17 devnull 	}
148 8d4a3514 2004-09-17 devnull 	cloneflag = 0;
149 8d4a3514 2004-09-17 devnull 	flags &= ~RFPROC;
150 8d4a3514 2004-09-17 devnull 	if(flags&RFMEM){
151 8d4a3514 2004-09-17 devnull 		cloneflag |= CLONE_VM;
152 8d4a3514 2004-09-17 devnull 		flags &= ~RFMEM;
153 8d4a3514 2004-09-17 devnull 	}
154 8d4a3514 2004-09-17 devnull 	if(!(flags&RFFDG))
155 8d4a3514 2004-09-17 devnull 		cloneflag |= CLONE_FILES;
156 8d4a3514 2004-09-17 devnull 	else
157 8d4a3514 2004-09-17 devnull 		flags &= ~RFFDG;
158 8d4a3514 2004-09-17 devnull 	nowait = flags&RFNOWAIT;
159 8d4a3514 2004-09-17 devnull 	if(!(flags&RFNOWAIT))
160 8d4a3514 2004-09-17 devnull 		cloneflag |= SIGCHLD;
161 8d4a3514 2004-09-17 devnull 	else
162 8d4a3514 2004-09-17 devnull 		flags &= ~RFNOWAIT;
163 8d4a3514 2004-09-17 devnull 	if(flags){
164 8d4a3514 2004-09-17 devnull 		fprint(2, "unknown rfork flags %x\n", flags);
165 8d4a3514 2004-09-17 devnull 		freestack(p);
166 8d4a3514 2004-09-17 devnull 		free(v);
167 8d4a3514 2004-09-17 devnull 		return -1;
168 8d4a3514 2004-09-17 devnull 	}
169 8d4a3514 2004-09-17 devnull 	v[0] = fn;
170 8d4a3514 2004-09-17 devnull 	v[1] = arg;
171 8d4a3514 2004-09-17 devnull 	v[2] = p;
172 8d4a3514 2004-09-17 devnull 	v[3] = &thepid;
173 8d4a3514 2004-09-17 devnull 	v[4] = (void*)cloneflag;
174 8d4a3514 2004-09-17 devnull 	thepid = -1;
175 8d4a3514 2004-09-17 devnull 	pid = clone(nowait ? trampnowait : tramp, p+fforkstacksize-16, cloneflag, v);
176 8d4a3514 2004-09-17 devnull 	if(pid > 0 && nowait){
177 8d4a3514 2004-09-17 devnull 		if(wait4(pid, &status, __WALL, 0) < 0)
178 8d4a3514 2004-09-17 devnull 			fprint(2, "ffork wait4: %r\n");
179 8d4a3514 2004-09-17 devnull 	}else
180 8d4a3514 2004-09-17 devnull 		thepid = pid;
181 8d4a3514 2004-09-17 devnull 	if(thepid == -1)
182 8d4a3514 2004-09-17 devnull 		freestack(p);
183 8d4a3514 2004-09-17 devnull 	else
184 8d4a3514 2004-09-17 devnull 		((Stack*)p)->pid = thepid;
185 8d4a3514 2004-09-17 devnull 	return thepid;
186 8d4a3514 2004-09-17 devnull }
187 8d4a3514 2004-09-17 devnull 
188 8d4a3514 2004-09-17 devnull int
189 8d4a3514 2004-09-17 devnull getfforkid(void)
190 8d4a3514 2004-09-17 devnull {
191 8d4a3514 2004-09-17 devnull 	return getpid();
192 8d4a3514 2004-09-17 devnull }
193 8d4a3514 2004-09-17 devnull