On Fri, Jul 31, 2015 at 11:18:22AM -0700, Jarno Rajahalme wrote:
> One question below,
One answer below ;-)
> Acked-by: Jarno Rajahalme <jrajaha...@nicira.com>
Thanks.
> > On Jul 29, 2015, at 11:42 PM, Ben Pfaff <b...@nicira.com> wrote:
> >
> > To be used in an upcoming commit.
> >
> > Signed-off-by: Ben Pfaff <b...@nicira.com>
> > ---
> > lib/list.h | 7 ++++++-
> > 1 file changed, 6 insertions(+), 1 deletion(-)
> >
> > diff --git a/lib/list.h b/lib/list.h
> > index 7ba1e35..c1b0891 100644
> > --- a/lib/list.h
> > +++ b/lib/list.h
> > @@ -23,6 +23,11 @@
> > #include "util.h"
> > #include "openvswitch/list.h"
> >
> > +/* Initializer for a list with pointers that will (probably) cause
> > segfaults if
> > + * dereferenced and, better yet, show up clearly in a debugger. */
> > +#define OVS_LIST_POISON { (void *) (uintptr_t) 0xccccccccccccccccULL, \
> > + (void *) (uintptr_t) 0xccccccccccccccccULL }
> > +
> > static inline void list_init(struct ovs_list *);
> > static inline void list_poison(struct ovs_list *);
> >
> > @@ -91,7 +96,7 @@ list_init(struct ovs_list *list)
> > static inline void
> > list_poison(struct ovs_list *list)
> > {
> > - memset(list, 0xcc, sizeof *list);
> > + *list = (struct ovs_list) OVS_LIST_POISON;
>
> Could the cast be part of the macro?
The short answer is "yes". Would you like it that way, then?
For C pedants only, continue reading for pedantry below the fold.
--8<--------------------------cut here-------------------------->8--
First, it's not a cast. It's a compound literal, and the C standard
says, in a footnote: "Note that [a compound literal] differs from a cast
expression. For example, a cast specifies a conversion to scalar types
or void only, and the result of a cast expression is not an lvalue."
Second, a compound literal isn't an initializer (except in the
degenerate sense that any expression is an initializer). The {...}
bracketed text in OVS_LIST_POISON is really an initializer. So I'd
probably update the comment above OVS_LIST_POISON at the same time, for
better pedantry.
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