Linux-2.6.12-rc2
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
diff --git a/net/unix/garbage.c b/net/unix/garbage.c
new file mode 100644
index 0000000..4bd95c8
--- /dev/null
+++ b/net/unix/garbage.c
@@ -0,0 +1,312 @@
+/*
+ * NET3: Garbage Collector For AF_UNIX sockets
+ *
+ * Garbage Collector:
+ * Copyright (C) Barak A. Pearlmutter.
+ * Released under the GPL version 2 or later.
+ *
+ * Chopped about by Alan Cox 22/3/96 to make it fit the AF_UNIX socket problem.
+ * If it doesn't 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
+ * - we gather the stuff that should not be killed into tree
+ * and stack is just a path from root to the current pointer.
+ *
+ * Future optimizations:
+ *
+ * - don't just push entire root set; process in place
+ *
+ * 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:
+ * Alan Cox 07 Sept 1997 Vmalloc internal stack as needed.
+ * Cope with changing max_files.
+ * Al Viro 11 Oct 1998
+ * Graph may have cycles. That is, we can send the descriptor
+ * of foo to bar and vice versa. Current code chokes on that.
+ * Fix: move SCM_RIGHTS ones into the separate list and then
+ * skb_free() them all instead of doing explicit fput's.
+ * Another problem: since fput() may block somebody may
+ * create a new unix_socket when we are in the middle of sweep
+ * phase. Fix: revert the logic wrt MARKED. Mark everything
+ * upon the beginning and unmark non-junk ones.
+ *
+ * [12 Oct 1998] AAARGH! New code purges all SCM_RIGHTS
+ * sent to connect()'ed but still not accept()'ed sockets.
+ * Fixed. Old code had slightly different problem here:
+ * extra fput() in situation when we passed the descriptor via
+ * such socket and closed it (descriptor). That would happen on
+ * each unix_gc() until the accept(). Since the struct file in
+ * question would go to the free list and might be reused...
+ * That might be the reason of random oopses on filp_close()
+ * in unrelated processes.
+ *
+ * AV 28 Feb 1999
+ * Kill the explicit allocation of stack. Now we keep the tree
+ * with root in dummy + pointer (gc_current) to one of the nodes.
+ * Stack is represented as path from gc_current to dummy. Unmark
+ * now means "add to tree". Push == "make it a son of gc_current".
+ * Pop == "move gc_current to parent". We keep only pointers to
+ * parents (->gc_tree).
+ * AV 1 Mar 1999
+ * Damn. Added missing check for ->dead in listen queues scanning.
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/string.h>
+#include <linux/socket.h>
+#include <linux/un.h>
+#include <linux/net.h>
+#include <linux/fs.h>
+#include <linux/slab.h>
+#include <linux/skbuff.h>
+#include <linux/netdevice.h>
+#include <linux/file.h>
+#include <linux/proc_fs.h>
+#include <linux/tcp.h>
+
+#include <net/sock.h>
+#include <net/af_unix.h>
+#include <net/scm.h>
+
+/* Internal data structures and random procedures: */
+
+#define GC_HEAD ((struct sock *)(-1))
+#define GC_ORPHAN ((struct sock *)(-3))
+
+static struct sock *gc_current = GC_HEAD; /* stack of objects to mark */
+
+atomic_t unix_tot_inflight = ATOMIC_INIT(0);
+
+
+static struct sock *unix_get_socket(struct file *filp)
+{
+ struct sock *u_sock = NULL;
+ struct inode *inode = filp->f_dentry->d_inode;
+
+ /*
+ * Socket ?
+ */
+ if (S_ISSOCK(inode->i_mode)) {
+ struct socket * sock = SOCKET_I(inode);
+ struct sock * s = sock->sk;
+
+ /*
+ * PF_UNIX ?
+ */
+ if (s && sock->ops && sock->ops->family == PF_UNIX)
+ u_sock = s;
+ }
+ return u_sock;
+}
+
+/*
+ * 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)
+{
+ struct sock *s = unix_get_socket(fp);
+ if(s) {
+ atomic_inc(&unix_sk(s)->inflight);
+ atomic_inc(&unix_tot_inflight);
+ }
+}
+
+void unix_notinflight(struct file *fp)
+{
+ struct sock *s = unix_get_socket(fp);
+ if(s) {
+ atomic_dec(&unix_sk(s)->inflight);
+ atomic_dec(&unix_tot_inflight);
+ }
+}
+
+
+/*
+ * Garbage Collector Support Functions
+ */
+
+static inline struct sock *pop_stack(void)
+{
+ struct sock *p = gc_current;
+ gc_current = unix_sk(p)->gc_tree;
+ return p;
+}
+
+static inline int empty_stack(void)
+{
+ return gc_current == GC_HEAD;
+}
+
+static void maybe_unmark_and_push(struct sock *x)
+{
+ struct unix_sock *u = unix_sk(x);
+
+ if (u->gc_tree != GC_ORPHAN)
+ return;
+ sock_hold(x);
+ u->gc_tree = gc_current;
+ gc_current = x;
+}
+
+
+/* The external entry point: unix_gc() */
+
+void unix_gc(void)
+{
+ static DECLARE_MUTEX(unix_gc_sem);
+ int i;
+ struct sock *s;
+ struct sk_buff_head hitlist;
+ struct sk_buff *skb;
+
+ /*
+ * Avoid a recursive GC.
+ */
+
+ if (down_trylock(&unix_gc_sem))
+ return;
+
+ read_lock(&unix_table_lock);
+
+ forall_unix_sockets(i, s)
+ {
+ unix_sk(s)->gc_tree = GC_ORPHAN;
+ }
+ /*
+ * Everything is now marked
+ */
+
+ /* Invariant to be maintained:
+ - everything unmarked is either:
+ -- (a) on the stack, or
+ -- (b) has all of its children unmarked
+ - everything on the stack is always unmarked
+ - nothing is ever pushed onto the stack twice, because:
+ -- nothing previously unmarked is ever pushed on the stack
+ */
+
+ /*
+ * Push root set
+ */
+
+ forall_unix_sockets(i, s)
+ {
+ int open_count = 0;
+
+ /*
+ * If all instances of the descriptor are not
+ * in flight we are in use.
+ *
+ * Special case: when socket s is embrion, it may be
+ * hashed but still not in queue of listening socket.
+ * In this case (see unix_create1()) we set artificial
+ * negative inflight counter to close race window.
+ * It is trick of course and dirty one.
+ */
+ if (s->sk_socket && s->sk_socket->file)
+ open_count = file_count(s->sk_socket->file);
+ if (open_count > atomic_read(&unix_sk(s)->inflight))
+ maybe_unmark_and_push(s);
+ }
+
+ /*
+ * Mark phase
+ */
+
+ while (!empty_stack())
+ {
+ struct sock *x = pop_stack();
+ struct sock *sk;
+
+ spin_lock(&x->sk_receive_queue.lock);
+ skb = skb_peek(&x->sk_receive_queue);
+
+ /*
+ * Loop through all but first born
+ */
+
+ while (skb && skb != (struct sk_buff *)&x->sk_receive_queue) {
+ /*
+ * Do we have file descriptors ?
+ */
+ if(UNIXCB(skb).fp)
+ {
+ /*
+ * Process the descriptors of this socket
+ */
+ int nfd=UNIXCB(skb).fp->count;
+ struct file **fp = UNIXCB(skb).fp->fp;
+ while(nfd--)
+ {
+ /*
+ * Get the socket the fd matches if
+ * it indeed does so
+ */
+ if((sk=unix_get_socket(*fp++))!=NULL)
+ {
+ maybe_unmark_and_push(sk);
+ }
+ }
+ }
+ /* We have to scan not-yet-accepted ones too */
+ if (x->sk_state == TCP_LISTEN)
+ maybe_unmark_and_push(skb->sk);
+ skb=skb->next;
+ }
+ spin_unlock(&x->sk_receive_queue.lock);
+ sock_put(x);
+ }
+
+ skb_queue_head_init(&hitlist);
+
+ forall_unix_sockets(i, s)
+ {
+ struct unix_sock *u = unix_sk(s);
+
+ if (u->gc_tree == GC_ORPHAN) {
+ struct sk_buff *nextsk;
+
+ spin_lock(&s->sk_receive_queue.lock);
+ skb = skb_peek(&s->sk_receive_queue);
+ while (skb &&
+ skb != (struct sk_buff *)&s->sk_receive_queue) {
+ nextsk=skb->next;
+ /*
+ * Do we have file descriptors ?
+ */
+ if(UNIXCB(skb).fp)
+ {
+ __skb_unlink(skb, skb->list);
+ __skb_queue_tail(&hitlist,skb);
+ }
+ skb=nextsk;
+ }
+ spin_unlock(&s->sk_receive_queue.lock);
+ }
+ u->gc_tree = GC_ORPHAN;
+ }
+ read_unlock(&unix_table_lock);
+
+ /*
+ * Here we are. Hitlist is filled. Die.
+ */
+
+ __skb_queue_purge(&hitlist);
+ up(&unix_gc_sem);
+}
