Re: free(sc, M_DEVBUF) [Was: amd64 panic snd_hda - hdac_get_capabilities: Invalid corb size (0)]

On Wed, Jul 28, 2010 at 04:14:10PM +0300, Andriy Gapon wrote:
> on 27/07/2010 19:53 Gavin Atkinson said the following:
> > 
> > Thanks.  Can you try
> > http://people.freebsd.org/~gavin/mexas-hda-panic.diff
> > 
> > and see if that solves things for you?
> > 
> > (Credit goes to avg_at_ for looking into this before me :)
> 
> BTW, it seems that there is an epidemic of "free(sc, M_DEVBUF)" in sound drivers.
> And not only them, but I haven't looked at the other cases - perhaps the code
> there does something different and thus correct.
> 
> 
> glimpse -w M_DEVBUF | fgrep -w free | fgrep '(sc,'
> /usr/src/sys/dev/sound/pci/hda/hdac.c:  free(sc, M_DEVBUF);
> /usr/src/sys/net/if_lagg.c:             free(sc, M_DEVBUF);
> /usr/src/sys/net/if_lagg.c:                             free(sc, M_DEVBUF);
> /usr/src/sys/net/if_lagg.c:     free(sc, M_DEVBUF);
> /usr/src/sys/net/if_bridge.c:           free(sc, M_DEVBUF);
> /usr/src/sys/net/if_bridge.c:   free(sc, M_DEVBUF);
> /usr/src/sys/dev/sound/pci/ich.c:       free(sc, M_DEVBUF);
> /usr/src/sys/dev/sound/pci/ich.c:       free(sc, M_DEVBUF);
> /usr/src/sys/dev/sound/pci/maestro3.c:  free(sc, M_DEVBUF);
> /usr/src/sys/dev/sound/pci/maestro3.c:  free(sc, M_DEVBUF);
> /usr/src/sys/net/if_enc.c:              free(sc, M_DEVBUF);
> /usr/src/sys/sun4v/sun4v/simdisk.c:             free(sc, M_DEVBUF);
> /usr/src/sys/dev/ofw/ofw_disk.c:                free(sc, M_DEVBUF);
> /usr/src/sys/dev/sound/isa/ess.c:       free(sc, M_DEVBUF);
> /usr/src/sys/dev/sound/sbus/cs4231.c:   free(sc, M_DEVBUF);
> /usr/src/sys/dev/sound/pci/atiixp.c:    free(sc, M_DEVBUF);
> /usr/src/sys/dev/sound/pci/emu10kx-pcm.c:               free(sc, M_DEVBUF);
> /usr/src/sys/dev/sound/pci/emu10kx-pcm.c:       free(sc, M_DEVBUF);
> /usr/src/sys/dev/sound/pci/emu10kx-pcm.c:       free(sc, M_DEVBUF);
> /usr/src/sys/dev/sound/pci/ds1.c:       free(sc, M_DEVBUF);
> /usr/src/sys/dev/sound/pci/ds1.c:       free(sc, M_DEVBUF);
> /usr/src/sys/dev/sound/pci/cmi.c:               free(sc, M_DEVBUF);
> /usr/src/sys/dev/sound/pci/cmi.c:       free(sc, M_DEVBUF);
> /usr/src/sys/dev/sound/pci/neomagic.c:                          free(sc, M_DEVBUF);
> /usr/src/sys/dev/sound/pci/neomagic.c:                  free(sc, M_DEVBUF);
> /usr/src/sys/dev/sound/pci/neomagic.c:  free(sc, M_DEVBUF);
> /usr/src/sys/dev/sound/pci/neomagic.c:  free(sc, M_DEVBUF);
> /usr/src/sys/dev/sound/pci/solo.c:      free(sc, M_DEVBUF);
> /usr/src/sys/dev/sound/pci/als4000.c:   free(sc, M_DEVBUF);
> /usr/src/sys/dev/sound/pci/als4000.c:   free(sc, M_DEVBUF);
> /usr/src/sys/dev/sound/pci/vibes.c:     free(sc, M_DEVBUF);
> /usr/src/sys/dev/sound/pci/emu10k1.c:   free(sc, M_DEVBUF);
> /usr/src/sys/dev/sound/pci/emu10k1.c:   free(sc, M_DEVBUF);
> /usr/src/sys/dev/sound/pci/cs4281.c:     free(sc, M_DEVBUF);
> /usr/src/sys/dev/sound/pci/cs4281.c:     free(sc, M_DEVBUF);
> 
> 
> Good example of how get examples get multiplied.
> 

When I started to write snd_audiocs(4) for sparc64 I also noticed
that. The practice of sound driver was to explicitly allocate softc
structure in device attach routine and release it after use. I
don't remember details but other parts of sound subsystem seemed to
rely on the structure and changing it to use standard
device_get_softc(9) was not easy task.

> P.S.
> Actually all non-sound case seem to be correct, explicitly malloc-ed memory gets
> freed.
> 
> -- 
> Andriy Gapon