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linux-pinenote/net/can/proc.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

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/*
* proc.c - procfs support for Protocol family CAN core module
*
* Copyright (c) 2002-2007 Volkswagen Group Electronic Research
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of Volkswagen nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* Alternatively, provided that this notice is retained in full, this
* software may be distributed under the terms of the GNU General
* Public License ("GPL") version 2, in which case the provisions of the
* GPL apply INSTEAD OF those given above.
*
* The provided data structures and external interfaces from this code
* are not restricted to be used by modules with a GPL compatible license.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
* DAMAGE.
*
* Send feedback to <socketcan-users@lists.berlios.de>
*
*/
#include <linux/module.h>
#include <linux/proc_fs.h>
#include <linux/list.h>
#include <linux/rcupdate.h>
#include <linux/can/core.h>
#include "af_can.h"
/*
* proc filenames for the PF_CAN core
*/
#define CAN_PROC_VERSION "version"
#define CAN_PROC_STATS "stats"
#define CAN_PROC_RESET_STATS "reset_stats"
#define CAN_PROC_RCVLIST_ALL "rcvlist_all"
#define CAN_PROC_RCVLIST_FIL "rcvlist_fil"
#define CAN_PROC_RCVLIST_INV "rcvlist_inv"
#define CAN_PROC_RCVLIST_SFF "rcvlist_sff"
#define CAN_PROC_RCVLIST_EFF "rcvlist_eff"
#define CAN_PROC_RCVLIST_ERR "rcvlist_err"
static struct proc_dir_entry *can_dir;
static struct proc_dir_entry *pde_version;
static struct proc_dir_entry *pde_stats;
static struct proc_dir_entry *pde_reset_stats;
static struct proc_dir_entry *pde_rcvlist_all;
static struct proc_dir_entry *pde_rcvlist_fil;
static struct proc_dir_entry *pde_rcvlist_inv;
static struct proc_dir_entry *pde_rcvlist_sff;
static struct proc_dir_entry *pde_rcvlist_eff;
static struct proc_dir_entry *pde_rcvlist_err;
static int user_reset;
static const char rx_list_name[][8] = {
[RX_ERR] = "rx_err",
[RX_ALL] = "rx_all",
[RX_FIL] = "rx_fil",
[RX_INV] = "rx_inv",
[RX_EFF] = "rx_eff",
};
/*
* af_can statistics stuff
*/
static void can_init_stats(void)
{
/*
* This memset function is called from a timer context (when
* can_stattimer is active which is the default) OR in a process
* context (reading the proc_fs when can_stattimer is disabled).
*/
memset(&can_stats, 0, sizeof(can_stats));
can_stats.jiffies_init = jiffies;
can_pstats.stats_reset++;
if (user_reset) {
user_reset = 0;
can_pstats.user_reset++;
}
}
static unsigned long calc_rate(unsigned long oldjif, unsigned long newjif,
unsigned long count)
{
unsigned long rate;
if (oldjif == newjif)
return 0;
/* see can_stat_update() - this should NEVER happen! */
if (count > (ULONG_MAX / HZ)) {
printk(KERN_ERR "can: calc_rate: count exceeded! %ld\n",
count);
return 99999999;
}
rate = (count * HZ) / (newjif - oldjif);
return rate;
}
void can_stat_update(unsigned long data)
{
unsigned long j = jiffies; /* snapshot */
/* restart counting in timer context on user request */
if (user_reset)
can_init_stats();
/* restart counting on jiffies overflow */
if (j < can_stats.jiffies_init)
can_init_stats();
/* prevent overflow in calc_rate() */
if (can_stats.rx_frames > (ULONG_MAX / HZ))
can_init_stats();
/* prevent overflow in calc_rate() */
if (can_stats.tx_frames > (ULONG_MAX / HZ))
can_init_stats();
/* matches overflow - very improbable */
if (can_stats.matches > (ULONG_MAX / 100))
can_init_stats();
/* calc total values */
if (can_stats.rx_frames)
can_stats.total_rx_match_ratio = (can_stats.matches * 100) /
can_stats.rx_frames;
can_stats.total_tx_rate = calc_rate(can_stats.jiffies_init, j,
can_stats.tx_frames);
can_stats.total_rx_rate = calc_rate(can_stats.jiffies_init, j,
can_stats.rx_frames);
/* calc current values */
if (can_stats.rx_frames_delta)
can_stats.current_rx_match_ratio =
(can_stats.matches_delta * 100) /
can_stats.rx_frames_delta;
can_stats.current_tx_rate = calc_rate(0, HZ, can_stats.tx_frames_delta);
can_stats.current_rx_rate = calc_rate(0, HZ, can_stats.rx_frames_delta);
/* check / update maximum values */
if (can_stats.max_tx_rate < can_stats.current_tx_rate)
can_stats.max_tx_rate = can_stats.current_tx_rate;
if (can_stats.max_rx_rate < can_stats.current_rx_rate)
can_stats.max_rx_rate = can_stats.current_rx_rate;
if (can_stats.max_rx_match_ratio < can_stats.current_rx_match_ratio)
can_stats.max_rx_match_ratio = can_stats.current_rx_match_ratio;
/* clear values for 'current rate' calculation */
can_stats.tx_frames_delta = 0;
can_stats.rx_frames_delta = 0;
can_stats.matches_delta = 0;
/* restart timer (one second) */
mod_timer(&can_stattimer, round_jiffies(jiffies + HZ));
}
/*
* proc read functions
*
* From known use-cases we expect about 10 entries in a receive list to be
* printed in the proc_fs. So PAGE_SIZE is definitely enough space here.
*
*/
static int can_print_rcvlist(char *page, int len, struct hlist_head *rx_list,
struct net_device *dev)
{
struct receiver *r;
struct hlist_node *n;
rcu_read_lock();
hlist_for_each_entry_rcu(r, n, rx_list, list) {
char *fmt = (r->can_id & CAN_EFF_FLAG)?
" %-5s %08X %08x %08x %08x %8ld %s\n" :
" %-5s %03X %08x %08lx %08lx %8ld %s\n";
len += snprintf(page + len, PAGE_SIZE - len, fmt,
DNAME(dev), r->can_id, r->mask,
(unsigned long)r->func, (unsigned long)r->data,
r->matches, r->ident);
/* does a typical line fit into the current buffer? */
/* 100 Bytes before end of buffer */
if (len > PAGE_SIZE - 100) {
/* mark output cut off */
len += snprintf(page + len, PAGE_SIZE - len,
" (..)\n");
break;
}
}
rcu_read_unlock();
return len;
}
static int can_print_recv_banner(char *page, int len)
{
/*
* can1. 00000000 00000000 00000000
* ....... 0 tp20
*/
len += snprintf(page + len, PAGE_SIZE - len,
" device can_id can_mask function"
" userdata matches ident\n");
return len;
}
static int can_proc_read_stats(char *page, char **start, off_t off,
int count, int *eof, void *data)
{
int len = 0;
len += snprintf(page + len, PAGE_SIZE - len, "\n");
len += snprintf(page + len, PAGE_SIZE - len,
" %8ld transmitted frames (TXF)\n",
can_stats.tx_frames);
len += snprintf(page + len, PAGE_SIZE - len,
" %8ld received frames (RXF)\n", can_stats.rx_frames);
len += snprintf(page + len, PAGE_SIZE - len,
" %8ld matched frames (RXMF)\n", can_stats.matches);
len += snprintf(page + len, PAGE_SIZE - len, "\n");
if (can_stattimer.function == can_stat_update) {
len += snprintf(page + len, PAGE_SIZE - len,
" %8ld %% total match ratio (RXMR)\n",
can_stats.total_rx_match_ratio);
len += snprintf(page + len, PAGE_SIZE - len,
" %8ld frames/s total tx rate (TXR)\n",
can_stats.total_tx_rate);
len += snprintf(page + len, PAGE_SIZE - len,
" %8ld frames/s total rx rate (RXR)\n",
can_stats.total_rx_rate);
len += snprintf(page + len, PAGE_SIZE - len, "\n");
len += snprintf(page + len, PAGE_SIZE - len,
" %8ld %% current match ratio (CRXMR)\n",
can_stats.current_rx_match_ratio);
len += snprintf(page + len, PAGE_SIZE - len,
" %8ld frames/s current tx rate (CTXR)\n",
can_stats.current_tx_rate);
len += snprintf(page + len, PAGE_SIZE - len,
" %8ld frames/s current rx rate (CRXR)\n",
can_stats.current_rx_rate);
len += snprintf(page + len, PAGE_SIZE - len, "\n");
len += snprintf(page + len, PAGE_SIZE - len,
" %8ld %% max match ratio (MRXMR)\n",
can_stats.max_rx_match_ratio);
len += snprintf(page + len, PAGE_SIZE - len,
" %8ld frames/s max tx rate (MTXR)\n",
can_stats.max_tx_rate);
len += snprintf(page + len, PAGE_SIZE - len,
" %8ld frames/s max rx rate (MRXR)\n",
can_stats.max_rx_rate);
len += snprintf(page + len, PAGE_SIZE - len, "\n");
}
len += snprintf(page + len, PAGE_SIZE - len,
" %8ld current receive list entries (CRCV)\n",
can_pstats.rcv_entries);
len += snprintf(page + len, PAGE_SIZE - len,
" %8ld maximum receive list entries (MRCV)\n",
can_pstats.rcv_entries_max);
if (can_pstats.stats_reset)
len += snprintf(page + len, PAGE_SIZE - len,
"\n %8ld statistic resets (STR)\n",
can_pstats.stats_reset);
if (can_pstats.user_reset)
len += snprintf(page + len, PAGE_SIZE - len,
" %8ld user statistic resets (USTR)\n",
can_pstats.user_reset);
len += snprintf(page + len, PAGE_SIZE - len, "\n");
*eof = 1;
return len;
}
static int can_proc_read_reset_stats(char *page, char **start, off_t off,
int count, int *eof, void *data)
{
int len = 0;
user_reset = 1;
if (can_stattimer.function == can_stat_update) {
len += snprintf(page + len, PAGE_SIZE - len,
"Scheduled statistic reset #%ld.\n",
can_pstats.stats_reset + 1);
} else {
if (can_stats.jiffies_init != jiffies)
can_init_stats();
len += snprintf(page + len, PAGE_SIZE - len,
"Performed statistic reset #%ld.\n",
can_pstats.stats_reset);
}
*eof = 1;
return len;
}
static int can_proc_read_version(char *page, char **start, off_t off,
int count, int *eof, void *data)
{
int len = 0;
len += snprintf(page + len, PAGE_SIZE - len, "%s\n",
CAN_VERSION_STRING);
*eof = 1;
return len;
}
static int can_proc_read_rcvlist(char *page, char **start, off_t off,
int count, int *eof, void *data)
{
/* double cast to prevent GCC warning */
int idx = (int)(long)data;
int len = 0;
struct dev_rcv_lists *d;
struct hlist_node *n;
len += snprintf(page + len, PAGE_SIZE - len,
"\nreceive list '%s':\n", rx_list_name[idx]);
rcu_read_lock();
hlist_for_each_entry_rcu(d, n, &can_rx_dev_list, list) {
if (!hlist_empty(&d->rx[idx])) {
len = can_print_recv_banner(page, len);
len = can_print_rcvlist(page, len, &d->rx[idx], d->dev);
} else
len += snprintf(page + len, PAGE_SIZE - len,
" (%s: no entry)\n", DNAME(d->dev));
/* exit on end of buffer? */
if (len > PAGE_SIZE - 100)
break;
}
rcu_read_unlock();
len += snprintf(page + len, PAGE_SIZE - len, "\n");
*eof = 1;
return len;
}
static int can_proc_read_rcvlist_sff(char *page, char **start, off_t off,
int count, int *eof, void *data)
{
int len = 0;
struct dev_rcv_lists *d;
struct hlist_node *n;
/* RX_SFF */
len += snprintf(page + len, PAGE_SIZE - len,
"\nreceive list 'rx_sff':\n");
rcu_read_lock();
hlist_for_each_entry_rcu(d, n, &can_rx_dev_list, list) {
int i, all_empty = 1;
/* check wether at least one list is non-empty */
for (i = 0; i < 0x800; i++)
if (!hlist_empty(&d->rx_sff[i])) {
all_empty = 0;
break;
}
if (!all_empty) {
len = can_print_recv_banner(page, len);
for (i = 0; i < 0x800; i++) {
if (!hlist_empty(&d->rx_sff[i]) &&
len < PAGE_SIZE - 100)
len = can_print_rcvlist(page, len,
&d->rx_sff[i],
d->dev);
}
} else
len += snprintf(page + len, PAGE_SIZE - len,
" (%s: no entry)\n", DNAME(d->dev));
/* exit on end of buffer? */
if (len > PAGE_SIZE - 100)
break;
}
rcu_read_unlock();
len += snprintf(page + len, PAGE_SIZE - len, "\n");
*eof = 1;
return len;
}
/*
* proc utility functions
*/
static struct proc_dir_entry *can_create_proc_readentry(const char *name,
mode_t mode,
read_proc_t *read_proc,
void *data)
{
if (can_dir)
return create_proc_read_entry(name, mode, can_dir, read_proc,
data);
else
return NULL;
}
static void can_remove_proc_readentry(const char *name)
{
if (can_dir)
remove_proc_entry(name, can_dir);
}
/*
* can_init_proc - create main CAN proc directory and procfs entries
*/
void can_init_proc(void)
{
/* create /proc/net/can directory */
can_dir = proc_mkdir("can", init_net.proc_net);
if (!can_dir) {
printk(KERN_INFO "can: failed to create /proc/net/can . "
"CONFIG_PROC_FS missing?\n");
return;
}
/* own procfs entries from the AF_CAN core */
pde_version = can_create_proc_readentry(CAN_PROC_VERSION, 0644,
can_proc_read_version, NULL);
pde_stats = can_create_proc_readentry(CAN_PROC_STATS, 0644,
can_proc_read_stats, NULL);
pde_reset_stats = can_create_proc_readentry(CAN_PROC_RESET_STATS, 0644,
can_proc_read_reset_stats, NULL);
pde_rcvlist_err = can_create_proc_readentry(CAN_PROC_RCVLIST_ERR, 0644,
can_proc_read_rcvlist, (void *)RX_ERR);
pde_rcvlist_all = can_create_proc_readentry(CAN_PROC_RCVLIST_ALL, 0644,
can_proc_read_rcvlist, (void *)RX_ALL);
pde_rcvlist_fil = can_create_proc_readentry(CAN_PROC_RCVLIST_FIL, 0644,
can_proc_read_rcvlist, (void *)RX_FIL);
pde_rcvlist_inv = can_create_proc_readentry(CAN_PROC_RCVLIST_INV, 0644,
can_proc_read_rcvlist, (void *)RX_INV);
pde_rcvlist_eff = can_create_proc_readentry(CAN_PROC_RCVLIST_EFF, 0644,
can_proc_read_rcvlist, (void *)RX_EFF);
pde_rcvlist_sff = can_create_proc_readentry(CAN_PROC_RCVLIST_SFF, 0644,
can_proc_read_rcvlist_sff, NULL);
}
/*
* can_remove_proc - remove procfs entries and main CAN proc directory
*/
void can_remove_proc(void)
{
if (pde_version)
can_remove_proc_readentry(CAN_PROC_VERSION);
if (pde_stats)
can_remove_proc_readentry(CAN_PROC_STATS);
if (pde_reset_stats)
can_remove_proc_readentry(CAN_PROC_RESET_STATS);
if (pde_rcvlist_err)
can_remove_proc_readentry(CAN_PROC_RCVLIST_ERR);
if (pde_rcvlist_all)
can_remove_proc_readentry(CAN_PROC_RCVLIST_ALL);
if (pde_rcvlist_fil)
can_remove_proc_readentry(CAN_PROC_RCVLIST_FIL);
if (pde_rcvlist_inv)
can_remove_proc_readentry(CAN_PROC_RCVLIST_INV);
if (pde_rcvlist_eff)
can_remove_proc_readentry(CAN_PROC_RCVLIST_EFF);
if (pde_rcvlist_sff)
can_remove_proc_readentry(CAN_PROC_RCVLIST_SFF);
if (can_dir)
proc_net_remove(&init_net, "can");
}
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