From owner-freebsd-current  Sat Feb  9 11:20:43 2002
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Date: Sat, 9 Feb 2002 11:04:29 -0800 (PST)
From: Julian Elischer <julian@elischer.org>
To: Bruce Evans <bde@zeta.org.au>
Cc: John Baldwin <jhb@FreeBSD.ORG>,
	FreeBSD current users <current@FreeBSD.ORG>
Subject: Re: cred stuff..
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On Sun, 10 Feb 2002, Bruce Evans wrote:

> On Fri, 8 Feb 2002, Julian Elischer wrote:
> 
> > I'd like to commit the code to keep the ucred across userland,
> > with the code to clear it to NULL kept under DEBUG ifdefs.
> >
> > i.e.
> >
> > >  in trap(), ast() and syscall()
> > >
> > >         if (td->td_ucred != p->p_ucred) {
> > >                 if (td->td_ucred != NULL) {
> > >                         mtx_lock(&Giant);
> > >                         crfree(td->td_ucred);
> > >                         td->td_ucred = NULL;
> > >                         mtx_unlock(&Giant);
> > >                 }
> > >                 if (p->p_ucred != NULL) {
> > >                         PROC_LOCK(p);
> > >                         td->td_ucred = crhold(p->p_ucred);
> > > 	                      PROC_UNLOCK(p);
> > >                 }
> > >         }
> 
> Please fix the style bugs in this before committing:
> - explicit NULL in only one null pointer checks
> - excessive braces for one of the ifs.

fixed

> 
> > 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
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

> 
> The style of the null pointer check in this is bug for bug compatible
> with the corresponding one above.

which way would you prefer?

> 
> Bruce
> 
> 


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