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