kern/58989: vchans cause mplayer crash

[kris at obsecurity.org]

>Number:         58989
>Category:       kern
>Synopsis:       vchans cause mplayer crash
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Wed Nov 05 21:20:16 PST 2003
>Closed-Date:
>Last-Modified:
>Originator:     Kris Kennaway
>Release:        FreeBSD 5.1-RELEASE-p10 i386
>Organization:
>Environment:
System: FreeBSD rot13.obsecurity.org 5.1-RELEASE-p10 FreeBSD 5.1-RELEASE-p10 #0: Wed Oct 8 04:08:28 PDT 2003 kkenn at rot13.obsecurity.org:/usr/obj/usr/src/sys/ROT13 i386

pcm0: <AudioPCI ES1370> port 0xa400-0xa43f irq 9 at device 13.0 on pci2
>Description:
When hw.snd.pcm0.vchans=1, seeking on a movie stream (e.g. pressing
forward/back arror during playback) will cause mplayer to crash.  There are
no other applications accessing the sound driver, although vchans work as
expected to multiplex the sound if I try.

It is likely that the sound driver is behaving differently when vchans are
enabled (e.g. returning an unexpected error), and mplayer does not handle
this unexpected condition.  Without further debugging I cannot tell if mplayer
is at fault or the pcm driver.
>How-To-Repeat:
hw.snd.maxautovchans=5
hw.snd.pcm0.vchans=1

Install mplayer and use it to play a video file.  Press the right arrow a few
dozen times to skip through the movie.  At some point mplayer will crash.

>Fix:
Setting hw.snd.pcm0.vchans=0 "fixes" this problem.
>Release-Note:
>Audit-Trail:
>Unformatted: