On Thu, Dec 29, 2011 at 12:53:19PM +0000, Chris Rees wrote:
> 2011/12/29 Kostik Belousov <kostik...@gmail.com>:
> > On Thu, Dec 29, 2011 at 11:46:57AM +0000, Chris Rees wrote:
> >> 2011/12/28 Kostik Belousov <kostik...@gmail.com>:
> >> > On Wed, Dec 28, 2011 at 02:53:42PM +0000, Chris Rees wrote:
> >> >> 2011/12/28 Kostik Belousov <kostik...@gmail.com>:
> >> >> > On Wed, Dec 28, 2011 at 12:23:58PM +0000, Chris Rees wrote:
> >> >> >> On 28 December 2011 12:21, Daniel O'Connor <docon...@gsoft.com.au>
> >> >> >> wrote:
> >> >> >> >
> >> >> >> > On 28/12/2011, at 22:07, Chris Rees wrote:
> >> >> >> >> Is there a simple way to check for existence of a driver? I could
> >> >> >> >> even check for /dev/sndstat, though that doesn't seem elegant to
> >> >> >> >> me...
> >> >> >> >
> >> >> >> > kldstat -v, but really /dev/sndstat seems simpler and just as
> >> >> >> > effective.
> >> >> >> >
> >> >> >>
> >> >> >> Cheers-- I was thinking of a kernel-level function though.
> >> >> >>
> >> >> >> cognet@ suggested using modfind("sound"), I'll go with that.
> >> >> > Obvious question is what the panic is. Checking for modules loaded is
> >> >> > papering over some issue.
> >> >>
> >> >> True, although I figured that it was a simple conflict, possibly to do
> >> >> with sndstat.
> >> >>
> >> >> Also, I'm getting panics with the following patch, whether sound is
> >> >> loaded or not :)
> >> >>
> >> >> + if (modfind("sound") >= 0)
> >> >> + {
> >> >> + cmn_err (CE_WARN, "A conflicting sound driver is already
> >> >> loaded");
> >> >> + return EBUSY;
> >> >> + }
> >> >> +
> >> >>
> >> >> Is there a better way to handle such conflicts?
> >> >
> >> > You have missed the point. There is some bug in oss driver that causing
> >> > the panic. Presumed 'conflict' cannot cause the harm itself, besides not
> >> > allowing second driver to attach to the same device, and should not
> >> > result
> >> > in panic. Trying to implement a half-measure that only covers the problem
> >> > you do a mis-service.
> >> >
> >> > And you still did not provided the panic message.
> >>
> >> I'm sorry, you're right. However, your guess was in fact correct;
> >> make_dev was being called, which returned a null pointer because it
> >> failed.
> >>
> >> The patch at [1] stops the panic, however I was hoping that returning
> >> EBUSY would abort loading the module... At the moment it loads the
> >> module, and doesn't create the sndstat dev, which causes weird errors
> >> with the oss binary commands.
> >>
> >> Since this solves the panic and anyone should be able to work out from
> >> the warning message what the problem is, AND this is a port that
> >> apparently no-one else uses, should this be sufficient?
> >>
> >> BTW, it only affects FreeBSD 9+, couldn't reproduce on my 8.2 dev
> >> machine, but could once I upgraded it.
> > On 8.2, there is no check in the devfs for duplicated cdev names, AFAIR.
> > So you get absolutely undeterministic behaviour which driver is referenced
> > by devfs node.
> >
> >> Chris
> >>
> >> [1]
> >> http://www.bayofrum.net/~crees/patches/oss-patch-kernel-OS-FreeBSD-os_freebsd.c
> >
> > I highly recommend to return error in case of any make_dev_p(9) failure, and
> > not only EEXIST.
>
> That'd be great-- but I can't work out how to do it :(
>
> Do I need to return a different value?
error = make_dev_p();
if (error != 0) {
printf("Error creating device node /dev/%s: %d\n", name, error);
return (error);
}
Or I do not understand your question.
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