android_kernel_xiaomi_sm8350/net/irda/irproc.c
Alexey Dobriyan 99b7623380 proc 2/2: remove struct proc_dir_entry::owner
Setting ->owner as done currently (pde->owner = THIS_MODULE) is racy
as correctly noted at bug #12454. Someone can lookup entry with NULL
->owner, thus not pinning enything, and release it later resulting
in module refcount underflow.

We can keep ->owner and supply it at registration time like ->proc_fops
and ->data.

But this leaves ->owner as easy-manipulative field (just one C assignment)
and somebody will forget to unpin previous/pin current module when
switching ->owner. ->proc_fops is declared as "const" which should give
some thoughts.

->read_proc/->write_proc were just fixed to not require ->owner for
protection.

rmmod'ed directories will be empty and return "." and ".." -- no harm.
And directories with tricky enough readdir and lookup shouldn't be modular.
We definitely don't want such modular code.

Removing ->owner will also make PDE smaller.

So, let's nuke it.

Kudos to Jeff Layton for reminding about this, let's say, oversight.

http://bugzilla.kernel.org/show_bug.cgi?id=12454

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
2009-03-31 01:14:44 +04:00

99 lines
2.5 KiB
C

/*********************************************************************
*
* Filename: irproc.c
* Version: 1.0
* Description: Various entries in the /proc file system
* Status: Experimental.
* Author: Thomas Davis, <ratbert@radiks.net>
* Created at: Sat Feb 21 21:33:24 1998
* Modified at: Sun Nov 14 08:54:54 1999
* Modified by: Dag Brattli <dagb@cs.uit.no>
*
* Copyright (c) 1998-1999, Dag Brattli <dagb@cs.uit.no>
* Copyright (c) 1998, Thomas Davis, <ratbert@radiks.net>,
* All Rights Reserved.
*
* 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.
*
* I, Thomas Davis, provide no warranty for any of this software.
* This material is provided "AS-IS" and at no charge.
*
********************************************************************/
#include <linux/miscdevice.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/module.h>
#include <linux/init.h>
#include <net/net_namespace.h>
#include <net/irda/irda.h>
#include <net/irda/irlap.h>
#include <net/irda/irlmp.h>
extern struct file_operations discovery_seq_fops;
extern struct file_operations irlap_seq_fops;
extern struct file_operations irlmp_seq_fops;
extern struct file_operations irttp_seq_fops;
extern struct file_operations irias_seq_fops;
struct irda_entry {
const char *name;
struct file_operations *fops;
};
struct proc_dir_entry *proc_irda;
EXPORT_SYMBOL(proc_irda);
static struct irda_entry irda_dirs[] = {
{"discovery", &discovery_seq_fops},
{"irttp", &irttp_seq_fops},
{"irlmp", &irlmp_seq_fops},
{"irlap", &irlap_seq_fops},
{"irias", &irias_seq_fops},
};
/*
* Function irda_proc_register (void)
*
* Register irda entry in /proc file system
*
*/
void __init irda_proc_register(void)
{
int i;
struct proc_dir_entry *d;
proc_irda = proc_mkdir("irda", init_net.proc_net);
if (proc_irda == NULL)
return;
for (i = 0; i < ARRAY_SIZE(irda_dirs); i++)
d = proc_create(irda_dirs[i].name, 0, proc_irda,
irda_dirs[i].fops);
}
/*
* Function irda_proc_unregister (void)
*
* Unregister irda entry in /proc file system
*
*/
void irda_proc_unregister(void)
{
int i;
if (proc_irda) {
for (i=0; i<ARRAY_SIZE(irda_dirs); i++)
remove_proc_entry(irda_dirs[i].name, proc_irda);
remove_proc_entry("irda", init_net.proc_net);
proc_irda = NULL;
}
}