linux-kernel - Re: kref refcounting breakage in mainline

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Thu, 15 Mar 2007 09:32:26 +0100
From:	Mike Galbraith <efault@....de>
To:	Greg KH <greg@...ah.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Tejun Heo <htejun@...il.com>,
	Kay Sievers <kay.sievers@...y.org>,
	linux-kernel@...r.kernel.org, Adrian Bunk <bunk@...sta.de>
Subject: Re: kref refcounting breakage in mainline

On Thu, 2007-03-15 at 01:06 -0700, Greg KH wrote:

> That's good.  But why don't we have a module name for this driver?
> 
> And if we don't have a module name, why would there be a symlink to
> remove?  That's what is keeping your module from unloading, right?

Ya got me, but according to my debug logs, what's causing my lockup is
the reference we add while making the symlink when we hit...
 if (driver_name) in module_add_driver().  Maybe we go through there
twice, once with a name, and once without?  Dunno.
 
> > [   24.670410] ipmi message handler version 39.1
> > [   24.675000] ipmi device interface
> > [   24.678542] IPMI System Interface driver.
> > [   24.703956] BUG: at kernel/module.c:2429 module_remove_driver()
> > [   24.716837]  [<c0105086>] show_trace_log_lvl+0x1a/0x30
> > [   24.728909]  [<c01057b2>] show_trace+0x12/0x14
> > [   24.740239]  [<c0105856>] dump_stack+0x16/0x18
> > [   24.751469]  [<c01441ce>] module_remove_driver+0xa5/0xa7
> > [   24.763584]  [<c035a014>] bus_remove_driver+0x6d/0x82
> > [   24.775390]  [<c035a978>] driver_unregister+0xb/0x18
> > [   24.787019]  [<c034c8c2>] init_ipmi_si+0x7a9/0x7c1
> > [   24.798450]  [<c06705bc>] init+0x144/0x26c
> > [   24.809129]  [<c0104cfb>] kernel_thread_helper+0x7/0x1c
> > [   24.820916]  =======================
> > [   24.830926] ipmi_si: Unable to find any System Interface(s)
> > [   24.842952] IPMI Watchdog: driver initialized
> >   24.853749] Copyright (C) 2004 MontaVista Software - IPMI Powerdown via sys_reboot.
> 
> With the above change, it all works correctly?

I don't know about _correctly_, but my diag patch _boots_, as does your
patch plus my addon diag bits.

> If the ipmi driver is loaded, what does the /sys/module/MODULE_NAME/
> tree look like (replacing MODULE_NAME with whatever the module name
> really is, sorry, I don't know)?

Well, I will never see that, because ipmi_si finds no interfaces, so
always backs out.  After backout, with my patch and yours + my addons, I
have there leftovers.

root@...er: ls -R /sys/module/ipmi_si
/sys/module/ipmi_si:
drivers  parameters

/sys/module/ipmi_si/drivers:

/sys/module/ipmi_si/parameters:
bt_debug  hotmod  kcs_debug  smic_debug

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/