From owner-freebsd-current  Sat Feb  9 17: 5:50 2002
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Date: Sun, 10 Feb 2002 12:08:12 +1100 (EST)
From: Bruce Evans <bde@zeta.org.au>
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To: Julian Elischer <julian@elischer.org>
Cc: John Baldwin <jhb@FreeBSD.ORG>,
	FreeBSD current users <current@FreeBSD.ORG>
Subject: Re: cred stuff..
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On Sat, 9 Feb 2002, Julian Elischer wrote:

> On Sun, 10 Feb 2002, Bruce Evans wrote:
>
> > On Fri, 8 Feb 2002, Julian Elischer wrote:
> ...
> > > and in userret() and ast()
> > >
> > > >#ifdef DEBUG  /*your choice of variable here*/
> > > >                 if (td->td_ucred != NULL) {
> > > >                         mtx_lock(&Giant);
> > > >                         crfree(td->td_ucred);
> > > >                         td->td_ucred = NULL;
> > > >                         mtx_unlock(&Giant);
> > > >                 }
> > > >#endif
> >
> > I think this is better left where it is in the functions that aquire
> > the locks.  It can then be done unconditionally, and not in a loop.
>
> AST is not always called
> and userret is always called, but unfortunatly sometimes multiple times

userret() isn't always called either in my version :-).  When I'm
finished, it will never be called (but I might rename ast() to userret()
since it is essenttially the unusual case for the original userret()).

> if someone were to clean up AST/userret
> it would be easier, but I am not sure I understand all the issues..
>
> Particularly the interraction between ast() and userret() and the various
> possible ASTs

Logically, it belongs at the end of userret(), but I would prefer it
to be immediately after all calls to userret() like it almost is now
so that I don't have to change it.  ast() is not special here, modulo
optimizations -- it is just one caller of userret().  Think of it as
just an optimization of once case of trap().

> > The style of the null pointer check in this is bug for bug compatible
> > with the corresponding one above.
>
> which way would you prefer?

I prefer explicit comparisions with NULL and 0 except for booleans.

Bruce


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