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List:       linux-kernel
Subject:    Re: [2.1.132] Modularized sound oops, OPL3-SA1
From:       Alex Stewart <riche () crl ! com>
Date:       1998-12-27 7:14:19
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(I picked this up while browsing through a kernel archive for last week)

> With a modularized opl3sa1 sound card setup, it looks like soundcore.o's
> MOD_USE_COUNT is never fully decremented, even when all it's child modules
> are (auto or manually) unloaded, and the next attempt at autoloading the
> sound modules causes an oops.

I just wanted to note that I've seen the same behavior with 2.1.131 and
my (fixed) pas2 driver, though I haven't yet had it oops on me.  The
symptoms are as follows:

(using Kernel 2.1.131 (with linux-2.1.131-pas.patch posted to this list
earlier) with modutils 2.1.121 on a Pentium 75 (32MB RAM, 1.5GB HD))
 
  [root@mondas /]# insmod soundcore
  [root@mondas /]# lsmod
  Module                  Size  Used by
  soundcore               1968   0  (unused)
  [root@mondas /]# insmod sound
  [root@mondas /]# lsmod
  Module                  Size  Used by
  sound                  57084   0  (unused)
  soundcore               1968   3  [sound]
  [root@mondas /]# insmod pas2 io=0x388 irq=11 dma=7
  [root@mondas /]# lsmod
  Module                  Size  Used by
  pas2                   11376   0  (unused)
  sound                  57084   0  [pas2]
  soundcore               1968   6  [sound]
  [root@mondas /]# rmmod pas2
  [root@mondas /]# lsmod
  Module                  Size  Used by
  sound                  57084   0
  soundcore               1968   6  [sound]
  [root@mondas /]# insmod pas2 io=0x388 irq=11 dma=7
  [root@mondas /]# lsmod
  Module                  Size  Used by
  pas2                   11376   0  (unused)
  sound                  57084   0  [pas2]
  soundcore               1968   9  [sound]
  [root@mondas /]# rmmod pas2
  [root@mondas /]# lsmod
  Module                  Size  Used by
  sound                  57084   0
  soundcore               1968   9  [sound]
  [root@mondas /]# rmmod sound
  [root@mondas /]# lsmod
  Module                  Size  Used by
  soundcore               1968   6

(equivalent behavior when using 'modprobe pas2' or demand-loading/etc.)

I note that the soundcore use count goes up by 3 when the sound module
is loaded, which gets decremented properly when it's unloaded, but when
the pas2 module is loaded it gets incremented by the same amount (3)
which doesn't ever get decremented.  Could the loading of the pas2
module be erroneously causing the sound module's use of soundcore to be
counted again?

I don't know a lot about this aspect of the kernel stuff (just recently
started looking into module stuff) but one wonders if this might be a
problem with three(plus)-module chains (most other things I've seen
don't have dependencies deeper than 2 levels).  I don't know off hand of
any 4-deep chains I could try with my hardware or I would..

Anyway, just some speculations..  I'll post more if I come up with
anything more revealing.

Please CC any relevant questions/comments to me directly, as I am not
currently subscribed to the linux-kernel maillist.

-alex

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