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linux/drivers/media/video/videocodec.c
Alexey Dobriyan 9faa2d7582 V4L/DVB (7580): Fix concurrent read from /proc/videocodecs 
Observation one: ->write_proc and ->data assignments aren't needed. Removed.
Observation two: codecs lists are unprotected. Patch doesn't fix this.
Observation three:
	/proc/videocodecs printout is done to temporary _global_ buffer which
	is freed in between. Consequently, two users hitting this file can
	screwup each other.

Steps to reproduce:

	modprobe videocodec
	while true; do cat /proc/videocodecs &>/dev/null; done &
	while true; do cat /proc/videocodecs &>/dev/null; done &

The fix is switching to seq_files, this removes code, especially some
line-length "logic".

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Acked-by: Jan Kara <jack@suse.cz>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
2008-04-24 14:09:40 -03:00

409 lines
9.1 KiB
C
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/*
* VIDEO MOTION CODECs internal API for video devices
*
* Interface for MJPEG (and maybe later MPEG/WAVELETS) codec's
* bound to a master device.
*
* (c) 2002 Wolfgang Scherr <scherr@net4you.at>
*
* $Id: videocodec.c,v 1.1.2.8 2003/03/29 07:16:04 rbultje Exp $
*
* ------------------------------------------------------------------------
*
* 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.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*
* ------------------------------------------------------------------------
*/
#define VIDEOCODEC_VERSION "v0.2"
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/types.h>
#include <linux/slab.h>
// kernel config is here (procfs flag)
#ifdef CONFIG_PROC_FS
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <asm/uaccess.h>
#endif
#include "videocodec.h"
static int debug;
module_param(debug, int, 0);
MODULE_PARM_DESC(debug, "Debug level (0-4)");
#define dprintk(num, format, args...) \
do { \
if (debug >= num) \
printk(format, ##args); \
} while (0)
struct attached_list {
struct videocodec *codec;
struct attached_list *next;
};
struct codec_list {
const struct videocodec *codec;
int attached;
struct attached_list *list;
struct codec_list *next;
};
static struct codec_list *codeclist_top = NULL;
/* ================================================= */
/* function prototypes of the master/slave interface */
/* ================================================= */
struct videocodec *
videocodec_attach (struct videocodec_master *master)
{
struct codec_list *h = codeclist_top;
struct attached_list *a, *ptr;
struct videocodec *codec;
int res;
if (!master) {
dprintk(1, KERN_ERR "videocodec_attach: no data\n");
return NULL;
}
dprintk(2,
"videocodec_attach: '%s', flags %lx, magic %lx\n",
master->name, master->flags, master->magic);
if (!h) {
dprintk(1,
KERN_ERR
"videocodec_attach: no device available\n");
return NULL;
}
while (h) {
// attach only if the slave has at least the flags
// expected by the master
if ((master->flags & h->codec->flags) == master->flags) {
dprintk(4, "videocodec_attach: try '%s'\n",
h->codec->name);
if (!try_module_get(h->codec->owner))
return NULL;
codec =
kmalloc(sizeof(struct videocodec), GFP_KERNEL);
if (!codec) {
dprintk(1,
KERN_ERR
"videocodec_attach: no mem\n");
goto out_module_put;
}
memcpy(codec, h->codec, sizeof(struct videocodec));
snprintf(codec->name, sizeof(codec->name),
"%s[%d]", codec->name, h->attached);
codec->master_data = master;
res = codec->setup(codec);
if (res == 0) {
dprintk(3, "videocodec_attach '%s'\n",
codec->name);
ptr = kzalloc(sizeof(struct attached_list), GFP_KERNEL);
if (!ptr) {
dprintk(1,
KERN_ERR
"videocodec_attach: no memory\n");
goto out_kfree;
}
ptr->codec = codec;
a = h->list;
if (!a) {
h->list = ptr;
dprintk(4,
"videocodec: first element\n");
} else {
while (a->next)
a = a->next; // find end
a->next = ptr;
dprintk(4,
"videocodec: in after '%s'\n",
h->codec->name);
}
h->attached += 1;
return codec;
} else {
kfree(codec);
}
}
h = h->next;
}
dprintk(1, KERN_ERR "videocodec_attach: no codec found!\n");
return NULL;
out_module_put:
module_put(h->codec->owner);
out_kfree:
kfree(codec);
return NULL;
}
int
videocodec_detach (struct videocodec *codec)
{
struct codec_list *h = codeclist_top;
struct attached_list *a, *prev;
int res;
if (!codec) {
dprintk(1, KERN_ERR "videocodec_detach: no data\n");
return -EINVAL;
}
dprintk(2,
"videocodec_detach: '%s', type: %x, flags %lx, magic %lx\n",
codec->name, codec->type, codec->flags, codec->magic);
if (!h) {
dprintk(1,
KERN_ERR "videocodec_detach: no device left...\n");
return -ENXIO;
}
while (h) {
a = h->list;
prev = NULL;
while (a) {
if (codec == a->codec) {
res = a->codec->unset(a->codec);
if (res >= 0) {
dprintk(3,
"videocodec_detach: '%s'\n",
a->codec->name);
a->codec->master_data = NULL;
} else {
dprintk(1,
KERN_ERR
"videocodec_detach: '%s'\n",
a->codec->name);
a->codec->master_data = NULL;
}
if (prev == NULL) {
h->list = a->next;
dprintk(4,
"videocodec: delete first\n");
} else {
prev->next = a->next;
dprintk(4,
"videocodec: delete middle\n");
}
module_put(a->codec->owner);
kfree(a->codec);
kfree(a);
h->attached -= 1;
return 0;
}
prev = a;
a = a->next;
}
h = h->next;
}
dprintk(1, KERN_ERR "videocodec_detach: given codec not found!\n");
return -EINVAL;
}
int
videocodec_register (const struct videocodec *codec)
{
struct codec_list *ptr, *h = codeclist_top;
if (!codec) {
dprintk(1, KERN_ERR "videocodec_register: no data!\n");
return -EINVAL;
}
dprintk(2,
"videocodec: register '%s', type: %x, flags %lx, magic %lx\n",
codec->name, codec->type, codec->flags, codec->magic);
ptr = kzalloc(sizeof(struct codec_list), GFP_KERNEL);
if (!ptr) {
dprintk(1, KERN_ERR "videocodec_register: no memory\n");
return -ENOMEM;
}
ptr->codec = codec;
if (!h) {
codeclist_top = ptr;
dprintk(4, "videocodec: hooked in as first element\n");
} else {
while (h->next)
h = h->next; // find the end
h->next = ptr;
dprintk(4, "videocodec: hooked in after '%s'\n",
h->codec->name);
}
return 0;
}
int
videocodec_unregister (const struct videocodec *codec)
{
struct codec_list *prev = NULL, *h = codeclist_top;
if (!codec) {
dprintk(1, KERN_ERR "videocodec_unregister: no data!\n");
return -EINVAL;
}
dprintk(2,
"videocodec: unregister '%s', type: %x, flags %lx, magic %lx\n",
codec->name, codec->type, codec->flags, codec->magic);
if (!h) {
dprintk(1,
KERN_ERR
"videocodec_unregister: no device left...\n");
return -ENXIO;
}
while (h) {
if (codec == h->codec) {
if (h->attached) {
dprintk(1,
KERN_ERR
"videocodec: '%s' is used\n",
h->codec->name);
return -EBUSY;
}
dprintk(3, "videocodec: unregister '%s' is ok.\n",
h->codec->name);
if (prev == NULL) {
codeclist_top = h->next;
dprintk(4,
"videocodec: delete first element\n");
} else {
prev->next = h->next;
dprintk(4,
"videocodec: delete middle element\n");
}
kfree(h);
return 0;
}
prev = h;
h = h->next;
}
dprintk(1,
KERN_ERR
"videocodec_unregister: given codec not found!\n");
return -EINVAL;
}
#ifdef CONFIG_PROC_FS
static int proc_videocodecs_show(struct seq_file *m, void *v)
{
struct codec_list *h = codeclist_top;
struct attached_list *a;
seq_printf(m, "<S>lave or attached <M>aster name type flags magic ");
seq_printf(m, "(connected as)\n");
h = codeclist_top;
while (h) {
seq_printf(m, "S %32s %04x %08lx %08lx (TEMPLATE)\n",
h->codec->name, h->codec->type,
h->codec->flags, h->codec->magic);
a = h->list;
while (a) {
seq_printf(m, "M %32s %04x %08lx %08lx (%s)\n",
a->codec->master_data->name,
a->codec->master_data->type,
a->codec->master_data->flags,
a->codec->master_data->magic,
a->codec->name);
a = a->next;
}
h = h->next;
}
return 0;
}
static int proc_videocodecs_open(struct inode *inode, struct file *file)
{
return single_open(file, proc_videocodecs_show, NULL);
}
static const struct file_operations videocodecs_proc_fops = {
.owner = THIS_MODULE,
.open = proc_videocodecs_open,
.read = seq_read,
.llseek = seq_lseek,
.release = single_release,
};
#endif
/* ===================== */
/* hook in driver module */
/* ===================== */
static int __init
videocodec_init (void)
{
#ifdef CONFIG_PROC_FS
static struct proc_dir_entry *videocodec_proc_entry;
#endif
printk(KERN_INFO "Linux video codec intermediate layer: %s\n",
VIDEOCODEC_VERSION);
#ifdef CONFIG_PROC_FS
videocodec_proc_entry = proc_create("videocodecs", 0, NULL, &videocodecs_proc_fops);
if (!videocodec_proc_entry) {
dprintk(1, KERN_ERR "videocodec: can't init procfs.\n");
}
#endif
return 0;
}
static void __exit
videocodec_exit (void)
{
#ifdef CONFIG_PROC_FS
remove_proc_entry("videocodecs", NULL);
#endif
}
EXPORT_SYMBOL(videocodec_attach);
EXPORT_SYMBOL(videocodec_detach);
EXPORT_SYMBOL(videocodec_register);
EXPORT_SYMBOL(videocodec_unregister);
module_init(videocodec_init);
module_exit(videocodec_exit);
MODULE_AUTHOR("Wolfgang Scherr <scherr@net4you.at>");
MODULE_DESCRIPTION("Intermediate API module for video codecs "
VIDEOCODEC_VERSION);
MODULE_LICENSE("GPL");
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