From 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Sat, 16 Apr 2005 15:20:36 -0700 Subject: 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! --- net/unix/garbage.c | 312 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 312 insertions(+) create mode 100644 net/unix/garbage.c (limited to 'net/unix/garbage.c') diff --git a/net/unix/garbage.c b/net/unix/garbage.c new file mode 100644 index 000000000000..4bd95c8f5934 --- /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 +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include +#include +#include + +/* 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); +} -- cgit v1.2.3-55-g7522