From owner-freebsd-current  Mon Feb 11 19:29:16 2002
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Date: Sun, 10 Feb 2002 01:27:25 +1100 (EST)
From: Bruce Evans <bde@zeta.org.au>
To: Julian Elischer <julian@elischer.org>
Cc: John Baldwin <jhb@FreeBSD.ORG>, <current@FreeBSD.ORG>
Subject: Re: cred stuff..
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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) {
> >                 PROC_LOCK(p);
> >                 if (td->td_ucred) {
> >                         crfree(td->td_ucred);
> >                         td->td_ucred = NULL;
> >                 }
> >                 if (p->p_ucred != NULL) {
> >                         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.

> and in userret() and ast()
>
> >#ifdef DEBUG  /*your choice of variable here*/
> >                 PROC_LOCK(p);
> >                 if (td->td_ucred) {
> >                         crfree(td->td_ucred);
> >                         td->td_ucred = NULL;
> >                 }
> >                 PROC_UNLOCK(p);
> >#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.

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

Bruce


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