sound/pcm/* bugs (was: Re: page fault panic tracked down (selwakeuppri()) - really sound/pcm/*)

Stefan Ehmann shoesoft at
Sun Jan 18 05:43:42 PST 2004

On Sat, 2004-01-17 at 10:15, Don Lewis wrote:
> I think this problem can be caused by a transient malloc() M_NOWAIT
> failure.
> Changes in this version of the patch:
> 	When increasing blksz in chn_setblocksize(), increase the size
> 	of bufsoft before increasing bufhard, and decrease bufsoft after
> 	decreasing bufhard in an attempt to avoid the buffer overflow in
> 	feed_vchan_s16().
> 	Buffers are now allocated using M_WAITOK, requiring locks to
> 	be dropped for the malloc() calls.  This required adding a mutex
> 	parameter to sndbuf_remalloc().
> 	Locking order between parent and child channels is changed.  The
>         parent is now locked first and then the child.  The list of
>         children is protected by the parent's lock.  There are still
>         potential race conditions in the vchan creation/destruction code
>         because all the locks have to be dropped in order to call
>         malloc(), etc.
> 	Locking cleaned up to eliminate the need for MTX_RECURSE.
> 	A new mutex allocator for the channel mutexes was added that
> 	initializes the mutexes with the MTX_DUPOK flags so that multiple
> 	channel mutexes of the same type can be held at once.
> 	Locking simplification in dsp_ioctl().
> 	Added KASSERTs in chn_wrfeed().

Using this patch (and the small changes to avoid the esd problem) I got
an assertion triggered in channel.c: chn_wrfeed amt > source size

#0  doadump () at /usr/src/sys/kern/kern_shutdown.c:240
#1  0xc04e57c8 in boot (howto=256) at
#2  0xc04e5b57 in panic () at /usr/src/sys/kern/kern_shutdown.c:550
#3  0xc07e36cd in chn_wrfeed (c=0xc37a8880)
    at /usr/src/sys/dev/sound/pcm/channel.c:219
#4  0xc07e377f in chn_wrintr (c=0xc37a8880)
    at /usr/src/sys/dev/sound/pcm/channel.c:239
#5  0xc07e3f70 in chn_intr (c=0xc37a8880)
    at /usr/src/sys/dev/sound/pcm/channel.c:485
#6  0xc07fda2f in csa_intr (p=0xc37a8700)
    at /usr/src/sys/dev/sound/pci/csapcm.c:623
#7  0xc07fc724 in csa_intr (arg=0xc37a8600)
    at /usr/src/sys/dev/sound/pci/csa.c:532
#8  0xc04d1c62 in ithread_loop (arg=0xc1736b00)
    at /usr/src/sys/kern/kern_intr.c:544
#9  0xc04d0c54 in fork_exit (callout=0xc04d1ad0 <ithread_loop>, arg=0x0,

    frame=0x0) at /usr/src/sys/kern/kern_fork.c:797

In frame #3 amt evaluates to 2176, bufsize is 2048

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