kern/146031: [snd_hda] race condition when kldunload snd_hda sound called

[Alexander Best]

The following reply was made to PR kern/146031; it has been noted by GNATS.

From: Alexander Best <alexbestms at wwu.de>
To: Garrett Cooper <gcooper at FreeBSD.org>
Cc: <bug-followup at FreeBSD.org>
Subject: Re: kern/146031: [snd_hda] race condition when kldunload snd_hda
 sound called
Date: Sun, 25 Apr 2010 13:26:33 +0200 (CEST)

 running
 
 sh -c 'i=1; while [ 1 ] ; do echo "Try $i"; kldload snd_hda; kldunload snd_hda
 sound; : $(( i += 1 )); done'
 
 complains about sound.ko not being loaded, since unloading snd_hda.ko also
 unloads sound.ko. is this what you got too?
 
 i'm not sure this logic is correct. loading snd_hda.ko also loads sound.ko,
 since it depends on it. however i don't see why unloading snd_hda.ko also
 unloads sound.ko, since sound.ko has no dependencies and can exist without any
 snd_*.ko module.
 
 i wasn't able to trigger the panic however (command cancelled with i=350 or
 so).
 
 i'm running 9-CURRENT (r207154).
 
 -- 
 Alexander Best