Re: 2.4.4-ac4 - oops on unload "cdrom" module

Andrzej Krzysztofowicz (ankry@green.mif.pg.gda.pl)
Fri, 4 May 2001 23:10:22 +0200 (CEST)

> This oops happens when I run "rmmod cdrom" on a 2.4.4-ac4 kernel with
> CONFIG_SYSCTL enabled. It doesn't happen if CONFIG_SYSCTL is disabled.
>
> sr_mod isn't loaded at this point. Reference to sd_mod looks weird. After
> this oops the "cdrom" module remains in memory in the "deleted" state.

> Unable to handle kernel NULL pointer dereference at virtual address 00000008
[...]
> >>EIP; c0118051 <unregister_sysctl_table+5/2c> <=====

The following patch fixes unloading of cdrom module when no cdrom driver
loaded (2.4.5-pre, 2.4.4-ac):

--- drivers/cdrom/cdrom.c.old Fri May 4 22:44:31 2001
+++ drivers/cdrom/cdrom.c Fri May 4 22:54:36 2001
@@ -2698,7 +2698,8 @@

static void cdrom_sysctl_unregister(void)
{
- unregister_sysctl_table(cdrom_sysctl_header);
+ if (cdrom_sysctl_header)
+ unregister_sysctl_table(cdrom_sysctl_header);
}

#endif /* CONFIG_SYSCTL */

Andrzej

-- 
=======================================================================
  Andrzej M. Krzysztofowicz               ankry@mif.pg.gda.pl
  tel.  (0-58) 347 14 61
Wydz.Fizyki Technicznej i Matematyki Stosowanej Politechniki Gdanskiej
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