Re: CVS commit: src/sys/arch/x86/x86

[David Young <dyoung%pobox.com@localhost>]

On Fri, Feb 20, 2009 at 12:54:59AM +0100, Christoph Egger wrote:
> David Young wrote:
> > On Thu, Feb 19, 2009 at 11:34:14PM +0000, Christoph Egger wrote:
> >> Module Name:       src
> >> Committed By:      cegger
> >> Date:              Thu Feb 19 23:34:14 UTC 2009
> >>
> >> Modified Files:
> >>    src/sys/arch/x86/x86: bus_dma.c
> >>
> >> Log Message:
> >> bus_dmamap_create(): on failure, reset dmamp or drivers
> >> like nfe(4) try to call bus_dmamap_destroy() on an invalid dmamap in their 
> >> error path.
> > 
> > Christoph,
> > 
> > Please, back this change out and fix the drivers, instead.
> 
> I tried that for nfe.
> In nfe_alloc_tx_ring(), setting ring->map = NULL right before
> 'goto fail;' has no effect.
> In nfe_free_tx_ring() it calls bus_dmamap_destroy(), nonetheless then.

It looks to me like a lot of things can go wrong if nfe_attach() calls
nfe_free_tx_ring() before everything is set up.  You cannot fix all of
nfe's bugs by changing the x86 implementation of an MI API.

> Further, bus_dma(9) manpage is not clear about the parameters if they
> are intended to be NULL or undefined in error case.
> manpage just says, bus_dmamap_create returns non-zero in failure case.

I have tried to make the manual page clear, see bus_dma.9 rev 1.46.

Dave

-- 
David Young             OJC Technologies
dyoung%ojctech.com@localhost      Urbana, IL * (217) 278-3933