1 files changed, 75 insertions, 0 deletions
diff --git a/src/libthread/procstack.ch b/src/libthread/procstack.ch
new file mode 100644
index 00000000..ccf81866
--- /dev/null
+++ b/src/libthread/procstack.ch
@@ -0,0 +1,75 @@
+static int fforkstacksize = 16384;
+
+typedef struct Stack Stack;
+struct Stack
+{
+	Stack *next;
+	Stack *fnext;
+	int pid;
+};
+
+static Lock stacklock;
+static Stack *freestacks;
+static Stack *allstacks;
+static int stackmallocs;
+static void gc(void);
+
+static void*
+mallocstack(void)
+{
+	Stack *p;
+
+	lock(&stacklock);
+top:
+	p = freestacks;
+	if(p)
+		freestacks = p->fnext;
+	else{
+		if(stackmallocs++%1 == 0)
+			gc();
+		if(freestacks)
+			goto top;
+		p = malloc(fforkstacksize);
+		p->next = allstacks;
+		allstacks = p;
+	}
+	if(p)
+		p->pid = 1;
+	unlock(&stacklock);
+	return p;
+}
+
+static void
+gc(void)
+{
+	Stack *p;
+
+	for(p=allstacks; p; p=p->next){
+		if(p->pid > 1 && procexited(p->pid)){
+			if(0) fprint(2, "reclaim stack from %d\n", p->pid);
+			p->pid = 0;
+		}
+		if(p->pid == 0){
+			p->fnext = freestacks;
+			freestacks = p;
+		}
+	}
+}
+
+static void
+freestack(void *v)
+{
+	Stack *p;
+
+	p = v;
+	if(p == nil)
+		return;
+	lock(&stacklock);
+	p->fnext = freestacks;
+	p->pid = 0;
+	freestacks = p;
+	unlock(&stacklock);
+	return;
+}
+
+