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[/] [or1k/] [tags/] [before_ORP/] [uclinux/] [uClinux-2.0.x/] [net/] [unix/] [garbage.c] - Rev 901
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/* * NET3: Garbage Collector For AF_UNIX sockets * * Garbage Collector: * Copyright (C) Barak A. Pearlmutter. * Released under the GPL version 2 or later. * * 12/3/97 -- Flood * Internal stack is only allocated one page. On systems with NR_FILE * > 1024, this makes it quite easy for a user-space program to open * a large number of AF_UNIX domain sockets, causing the garbage * collection routines to run up against the wall (and panic). * Changed the MAX_STACK to be associated to the system-wide open file * maximum, and use vmalloc() instead of get_free_page() [as more than * one page may be necessary]. As noted below, this should ideally be * done with a linked list. * * 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 * * 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: * 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 * kfree_skb() 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 close_fp() in * unrelated processes. * */ #include <linux/kernel.h> #include <linux/major.h> #include <linux/signal.h> #include <linux/sched.h> #include <linux/errno.h> #include <linux/string.h> #include <linux/stat.h> #include <linux/socket.h> #include <linux/un.h> #include <linux/fcntl.h> #include <linux/termios.h> #include <linux/socket.h> #include <linux/sockios.h> #include <linux/net.h> #include <linux/in.h> #include <linux/fs.h> #include <linux/malloc.h> #include <asm/segment.h> #include <linux/skbuff.h> #include <linux/netdevice.h> #include <net/sock.h> #include <net/tcp.h> #include <net/af_unix.h> #include <linux/proc_fs.h> /* Internal data structures and random procedures: */ static unix_socket **stack; /* stack of objects to mark */ static int in_stack = 0; /* first free entry in stack */ static int max_stack; /* Calculated in unix_gc() */ extern inline unix_socket *unix_get_socket(struct file *filp) { unix_socket * u_sock = NULL; struct inode *inode = filp->f_inode; /* * Socket ? */ if (inode && inode->i_sock) { struct socket * s = &inode->u.socket_i; /* * AF_UNIX ? */ if (s->ops == &unix_proto_ops) u_sock = s->data; } 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) { 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 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; } 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; } extern inline void maybe_unmark_and_push(unix_socket *x) { if (!(x->protinfo.af_unix.marksweep&MARKED)) return; x->protinfo.af_unix.marksweep&=~MARKED; push_stack(x); } /* The external entry point: unix_gc() */ void unix_gc(void) { static int in_unix_gc=0; unix_socket *s; struct sk_buff *skb; struct sk_buff_head hitlist; /* * Avoid a recursive GC. */ if(in_unix_gc) return; in_unix_gc=1; max_stack = max_files; stack=(unix_socket **)vmalloc(max_stack * sizeof(unix_socket **)); if (!stack) { in_unix_gc=0; return; } /* * Everything is now marked */ for(s=unix_socket_list;s!=NULL;s=s->next) { s->protinfo.af_unix.marksweep|=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 */ 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_unmark_and_push(s); } /* * Mark phase */ while (!empty_stack()) { unix_socket *x = pop_stack(); unix_socket *f=NULL,*sk; 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, unmark the * rest. */ if(f==NULL) f=sk; else maybe_unmark_and_push(sk); } } } /* * If we are connecting we need to handle this too */ if(x->state == TCP_LISTEN) { if(f==NULL) f=skb->sk; else maybe_unmark_and_push(skb->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; } } } skb_queue_head_init(&hitlist); for(s=unix_socket_list;s!=NULL;s=s->next) { if (s->protinfo.af_unix.marksweep&MARKED) { struct sk_buff *nextsk; skb=skb_peek(&s->receive_queue); while(skb && skb != (struct sk_buff *)&s->receive_queue) { nextsk=skb->next; /* * Do we have file descriptors ? */ if(*(int *)(skb->h.filp)) { /* * Pull these buffers out of line * so they will each be freed once * at the end. */ skb_unlink(skb); skb_queue_tail(&hitlist,skb); } skb=nextsk; } } } /* * Here we are. Hitlist is filled. Die. */ while ((skb=skb_dequeue(&hitlist))!=NULL) { kfree_skb(skb, FREE_READ); } in_unix_gc=0; vfree(stack); }
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