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.. Message-ID: <Pine.BSF.4.21.0202091052570.7793-100000@InterJet.elischer.org> In-Reply-To: <20020210012027.E3321-100000@gamplex.bde.org>
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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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