Date: Sun, 16 Feb 2003 19:51:17 +0100 (CET) From: Jean-Yves Lefort <jylefort@brutele.be> To: FreeBSD-gnats-submit@FreeBSD.org Subject: kern/48338: pcm audio driver hogs /dev/dsp?.? Message-ID: <20030216185117.47EE922E35@jsite.lefort.net>
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>Number: 48338
>Category: kern
>Synopsis: pcm audio driver hogs /dev/dsp?.?
>Confidential: no
>Severity: serious
>Priority: medium
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Sun Feb 16 11:00:03 PST 2003
>Closed-Date:
>Last-Modified:
>Originator: Jean-Yves Lefort
>Release: FreeBSD 4.7-RELEASE-p3 i386
>Organization:
>Environment:
The problem has been experienced on:
$ uname -a
FreeBSD jsite.lefort.net 4.7-RELEASE-p3 FreeBSD 4.7-RELEASE-p3 #0: Tue Jan 7 23:46:56 CET 2003 jylefort@jsite.lefort.net:/usr/obj/usr/src/sys/JSITE i386
$ cat /dev/sndstat
FreeBSD Audio Driver (newpcm)
Installed devices:
pcm0: <AudioPCI ES1373-8> at io 0x9000 irq 11 (1p/1r/4v channels duplex)
$
and:
$ uname -a
FreeBSD noname 5.0-CURRENT FreeBSD 5.0-CURRENT #1: Sat Feb 1 00:57:38 EST 2003 refugee@noname:/usr/obj/usr/src/sys/NONAME i386
$ cat /dev/sndstat
FreeBSD Audio Driver (newpcm)
Installed devices:
pcm0: <CMedia CMI8738> at io 0xd800 irq 10 (1p/1r/0v channels duplex default)
$
>Description:
Under certain conditions, the pcm audio device driver hogs /dev/dsp?.?
("Device Busy").
It seems that the problem happens when a process tries to open a dsp
device shortly after the same device has been opened by another
process.
This might be related to the vchan code, as the hw.snd.pcm0.vchans
sysctl knob was set to 4 during my tests.
"fstat | grep dsp" gives nothing.
>How-To-Repeat:
$ while :; do play somesoundfile & done
This will quickly lock /dev/dsp0.0. Of course, be prepared to hit ^C,
since the & is not a typo. :)
>Fix:
If multiple virtual channels are in use when the problem first
appears, setting sysctl hw.snd.pcm0.vchans to locked_dsp_# - 1 and
then back to the original number unlocks the dsp device.
However, after locking the dsp device a second time, reducing
hw.snd.pcm0.vchans gives "Invalid argument" and the device is locked
for good: then, only a reboot helps.
>Release-Note:
>Audit-Trail:
>Unformatted:
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