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From
SubjectRe: [PATCHSET] 2.4.21-pre2-jp15
Date
Hi Margit,

You are right, I missed the obvious case when preempt is disabled at all. An
updated patch is here: http://infolinux.de/jp15/076_sysrq-preempt-log-fix-2

The proc_get_inode problem is for a long time now a vanilla kernel problem,
since the early days of 2.4.

I assume the proc_get_inode function is considered not to be exported because
the proc fs driver was likely to have race conditions, so Marcelo don't feel
ok with fixing it. The comx driver is broken with proc fs.

Maybe Gergely Madarasz <gorgo@itc.hu> (comx Maintainer) is going to fix it. My
favorite solution would be getting rid of proc_get_inode in
drivers/net/wan/comx.c

Al Viro announced a rework of proc fs a long time ago, I don't know if the
changes have been made.

http://www.cs.helsinki.fi/linux/linux-kernel/2001-24/0984.html

Willy Tarreau tried a fix in comx, but gave up:

http://www.cs.helsinki.fi/linux/linux-kernel/2002-25/0562.html

Some more URLs from Google:

http://www.cs.helsinki.fi/linux/linux-kernel/2001-12/0677.html
http://www.uwsg.iu.edu/hypermail/linux/kernel/0206.3/0466.html
http://www.cs.helsinki.fi/linux/linux-kernel/2002-37/0063.html
http://hypermail.idiosynkrasia.net/linux-kernel/archived/2002/week37/0122.html
http://www.van-dijk.net/linuxkernel/200218/0359.html.gz

etc.

From the ChangeLog of 2.4.0prerelease-ac6
o Fix proc_get_inode export (for comx) (Hans Grobler)

:-)

Also, the code in comx don't seem to be clean according to this NULL checker
tool. In fact, de->name is dereferenced without being checked.

[BUG] contra
/u2/engler/mc/oses/linux/2.4.4/drivers/net/wan/comx.c:920:comx_lookup:
ERROR:INTERNAL_NULL:924:920: [type=set] (set at line 924) Dereferencing NULL
ptr "de" illegally! [val=400]
{
struct proc_dir_entry *de;
struct inode *inode = NULL;
if ((de = (struct proc_dir_entry *) dir->u.generic_ip) != NULL) {
Error --->
for (de = de->subdir ; de ; de = de->next) {
if ((de && de->low_ino) &&
(de->namelen == dentry->d_name.len) &&
(memcmp(dentry->d_name.name, de->name,
Start --->
de->namelen) == 0)) {
if ((inode = proc_get_inode(dir->i_sb,
de->low_ino, de)) == NULL) {
printk(KERN_ERR "COMX: lookup error\n");
I don't have the hardware, so I can't help with a solid fix. While there is no
good solution, I recommend to disable the driver.

Jörg

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