Re: Serial-Core: USB-Serial port current issues.

[Greg KH <gregkh@suse.de>]

On Thu, Jun 15, 2006 at 10:29:40AM -0300, Luiz Fernando N. Capitulino wrote:
> On Wed, 14 Jun 2006 17:53:08 -0700
> Pete Zaitcev <zaitcev@redhat.com> wrote:
> 
> | On Wed, 14 Jun 2006 17:38:24 -0300, "Luiz Fernando N. Capitulino" <lcapitulino@mandriva.com.br> wrote:
> | 
> | >  I think BUG_ON(in_interrupt()) does the job. I'll try it here, and
> | > if it doesn't trigger I'll submit a patch to Andrew only for
> | > testing porpuses (ie, not for mainline).
> | 
> | Luiz, you can't be serious! You have to do a review and write call paths
> | on a piece of paper or however you prefer to do it. Your testing is
> | extremely limited as we know, you don't even have a null-modem cable.
> | So if the patch does not trip in your testing it tells you absolutely
> | nothing. But even in context of AKPM's tree you can't rely on run-time
> | checks to pick this sort of things.
> 
>  Hey, take it easy. :)
> 
>  I won't test it in my patches. I'll hack the Serial Core code and add
> debug code just before every call to those functions we want to know
> whether they run in interrupt context or not.
> 
>  Yeah, I know, it's still limited because the driver itself can call its
> methods directly in interrupt context. But I think it's a good start.
> 
> | And putting a BUG in there is irresponsible too. It's such a critical
> | subsystem. Drop bytes or return zero modem lines, but do not bug out.
> 
>  Well, I want the easier, fastest and non-questionable way to know whether
> they are called from an interrupt context or not. The first thing that
> came to my mind was: blow up everything if it has been called in
> interrupt context.
> 
>  But I'm open for suggestions, of course.

WARN_ON(in_interrupt());
is much nicer.  It gives you a full dump, yet lets the machine keep
working so that users can actually give you the bug report.

thanks,

greg k-h