patch-1.3.78 linux/net/unix/garbage.c

• Lines: 271
• Date: Mon Mar 25 08:58:28 1996
• Orig file: v1.3.77/linux/net/unix/garbage.c
• Orig date: Tue Mar 5 10:11:16 1996

diff -u --recursive --new-file v1.3.77/linux/net/unix/garbage.c linux/net/unix/garbage.c
@@ -1,13 +1,38 @@
 /*
- * NET3:	Garbage Collector For AF_UNIX sockets (STUB)
+ * NET3:	Garbage Collector For AF_UNIX sockets (STUBS)
  *
- * Authors:	
+ * Garbage Collector:
+ *	Copyright (C) Barak A. Pearlmutter.
+ *	Released under the GPL version 2 or later.
  *
- *		This program is free software; you can redistribute it and/or
- *		modify it under the terms of the GNU General Public License
- *		as published by the Free Software Foundation; either version
- *		2 of the License, or (at your option) any later version.
- * Fixes:
+ * NOTE:
+ *	We don't actually call this yet. I'm finishing some tests before I
+ *	enable it. The bold can add it in themselves.
+ *
+ * Chopped about by Alan Cox 22/3/96 to make it fit the AF_UNIX socket problem.
+ * If it doesnt work blame me, it worked when Barak sent it.
+ *
+ * Assumptions:
+ *
+ *  - object w/ a bit
+ *  - free list
+ *
+ * Current optimizations:
+ *
+ *  - explicit stack instead of recursion
+ *  - tail recurse on first born instead of immediate push/pop
+ *
+ *  Future optimizations:
+ *
+ *  - don't just push entire root set; process in place
+ *  - use linked list for internal stack
+ *
+ *	This program is free software; you can redistribute it and/or
+ *	modify it under the terms of the GNU General Public License
+ *	as published by the Free Software Foundation; either version
+ *	2 of the License, or (at your option) any later version.
+ *
+ *  Fixes:
  *
  */
  
@@ -35,19 +60,218 @@
 #include <net/tcp.h>
 #include <net/af_unix.h>
 #include <linux/proc_fs.h>
+
+/* Internal data structures and random procedures: */
+
+#define MAX_STACK 1000		/* Maximum depth of tree (about 1 page) */
+static unix_socket **stack;	/* stack of objects to mark */
+static int in_stack = 0;	/* first free entry in stack */
+
+
+extern inline unix_socket *unix_get_socket(struct file *filp)
+{
+	struct socket *s;
+	/*
+	 *	Socket ?
+	 */
+	if(filp->f_inode->i_mode!=S_IFSOCK)
+		return NULL;
+	s=&(filp->f_inode->u.socket_i);
+	/*
+	 *	AF_UNIX ?
+	 */
+	if(s->ops!=&unix_proto_ops)
+		return NULL;
+	/*
+	 *	Got one.
+	 */
+	return s->data;	
+}
+
+/*
+ *	Keep the number of times in flight count for the file
+ *	descriptor if it is for an AF_UNIX socket.
+ */
+ 
+void unix_inflight(struct file *fp)
+{
+	unix_socket *s=unix_get_socket(fp);
+	if(s)
+		s->protinfo.af_unix.inflight++;
+}
+
+void unix_notinflight(struct file *fp)
+{
+	unix_socket *s=unix_get_socket(fp);
+	if(s)
+		s->protinfo.af_unix.inflight--;
+}
+
+
 /*
- *	Garbage Collector Stubs
+ *	Garbage Collector Support Functions
  */
  
+extern inline void push_stack(unix_socket *x)
+{
+	if (in_stack == MAX_STACK)
+		panic("can't push onto full stack");
+	stack[in_stack++] = x;
+}
 
-int unix_gc_free=128;		/* GC slots free */
+extern inline unix_socket *pop_stack(void)
+{
+	if (in_stack == 0)
+		panic("can't pop empty gc stack");
+	return stack[--in_stack];
+}
+
+extern inline int empty_stack(void)
+{
+	return in_stack == 0;
+}
 
-void unix_gc_remove(struct file *fp)
+extern inline void maybe_mark_and_push(unix_socket *x)
 {
-	;
+	if (x->protinfo.af_unix.marksweep&MARKED)
+		return;
+	x->protinfo.af_unix.marksweep|=MARKED;
+	push_stack(x);
 }
 
-void unix_gc_add(struct sock *sk, struct file *fp)
+
+/* The external entry point: unix_gc() */
+
+void unix_gc(void)
 {
-	;
+	static int in_unix_gc=0;
+	unix_socket *s;
+	unix_socket *next;
+	
+	/*
+	 *	Avoid a recursive GC.
+	 */
+
+	if(in_unix_gc)
+		return;
+	in_unix_gc=1;
+	
+	stack=(unix_socket **)get_free_page(GFP_KERNEL);
+	
+	/*
+	 *	Assume everything is now unmarked 
+	 */
+
+	/* Invariant to be maintained:
+		- everything marked is either:
+		-- (a) on the stack, or
+		-- (b) has all of its children marked
+		- everything on the stack is always marked
+		- nothing is ever pushed onto the stack twice, because:
+		-- nothing previously marked is ever pushed on the stack
+	 */
+
+	/*
+	 *	Push root set
+	 */
+
+	for(s=unix_socket_list;s!=NULL;s=s->next)
+	{
+		/*
+		 *	If all instances of the descriptor are not
+		 *	in flight we are in use.
+		 */
+		if(s->socket && s->socket->file && s->socket->file->f_count > s->protinfo.af_unix.inflight)
+			maybe_mark_and_push(s);
+	}
+
+	/*
+	 *	Mark phase 
+	 */
+
+	while (!empty_stack())
+	{
+		unix_socket *x = pop_stack();
+		unix_socket *f=NULL,*sk;
+		struct sk_buff *skb;
+tail:		
+		skb=skb_peek(&x->receive_queue);
+		
+		/*
+		 *	Loop through all but first born 
+		 */
+		
+		while(skb && skb != (struct sk_buff *)&x->receive_queue)
+		{
+			/*
+			 *	Do we have file descriptors ?
+			 */
+			if(skb->h.filp)
+			{
+				/*
+				 *	Process the descriptors of this socket
+				 */
+				int nfd=*(int *)skb->h.filp;
+				struct file **fp=(struct file **)(skb->h.filp+sizeof(int));
+				while(nfd--)
+				{
+					/*
+					 *	Get the socket the fd matches if
+					 *	it indeed does so
+					 */
+					if((sk=unix_get_socket(*fp++))!=NULL)
+					{
+						/*
+						 *	Remember the first, mark the
+						 *	rest.
+						 */
+						if(f==NULL)
+							f=sk;
+						else
+							maybe_mark_and_push(sk);
+					}
+				}
+			}
+			skb=skb->next;
+		}
+		/*
+		 *	Handle first born specially 
+		 */
+
+		if (f) 
+		{
+			if (!(f->protinfo.af_unix.marksweep&MARKED))
+			{
+				f->protinfo.af_unix.marksweep|=MARKED;
+				x=f;
+				f=NULL;
+				goto tail;
+			}
+		}
+	}
+
+	/*
+	 *	Sweep phase.  NOTE: this part dominates the time complexity 
+	 */
+
+	for(s=unix_socket_list;s!=NULL;s=next)
+	{
+		next=s->next;
+		if (!(s->protinfo.af_unix.marksweep&MARKED))
+		{
+			/*
+			 *	We exist only in the passing tree of sockets
+			 *	that is no longer connected to active descriptors
+			 *	Time to die..
+			 */
+			if(s->socket && s->socket->file)
+				close_fp(s->socket->file);
+		}
+		else
+			s->protinfo.af_unix.marksweep&=~MARKED;	/* unmark everything for next collection */
+	}
+	
+	in_unix_gc=0;
+	
+	free_page((long)stack);
 }