On Wed, 2004-06-23 at 13:52, David Gwynne wrote:
> On Wed, 2004-06-23 at 13:32, Artur Grabowski wrote:
> > Henning Brauer <lists-openbsdtech@bsws.de> writes:
> >
> > > * Philipp Buehler <pb@openbsd.org> [2004-06-22 10:06]:
> > > > + TAILQ_FOREACH(ifgp, &ifp->if_groups, group_list) {
> > > > + TAILQ_REMOVE(&ifp->if_groups, ifgp, group_list);
> > >
> > > no... see manpage
> > >
> > > NOTES
> > > Trying to free a list in the following way is a common error:
> > >
> > > LIST_FOREACH(var, head, entry)
> > > free(var);
> > > free(head);
> > >
> > > Since var is free'd, the FOREACH() macro refers to a pointer that may
> > > have been reallocated already. Proper code needs a second variable.
> > >
> > > for (var = LIST_FIRST(head); var != LIST_END(head); var = nxt) {
> > > nxt = LIST_NEXT(var, entry);
> > > free(var);
> > > }
> > > LIST_INIT(head); /* to put the list back in order */
> >
> > Stop giving bad advice.
> >
> > while ((foo = TAILQ_FIRST(..)) != NULL) {
> > TAILQ_REMOVE(foo ...);
> > free(foo);
> > }
>
> Hennings advice is good if you're not removing every entry in the list
> as you loop through it.
>

Actually, here is a good example of applying the advice Henning gave:
http://www.itee.uq.edu.au/~chrisp/Op...ter_free2.diff

This applies against current and fixes a panic that is obviously very
rare since no one except Chris seems to have triggered it.

DG

> >
> > //art
> >




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