[ovs-dev] [PATCH v2 1/5] classifier: Constify RCU pointers.

[Ben Pfaff]

On Thu, Nov 06, 2014 at 11:29:26AM -0800, Jarno Rajahalme wrote:
> 
> On Nov 6, 2014, at 11:08 AM, Ben Pfaff <blp at nicira.com> wrote:
> 
> > On Thu, Nov 06, 2014 at 11:06:59AM -0800, Ben Pfaff wrote:
> >> On Thu, Nov 06, 2014 at 11:02:56AM -0800, Ben Pfaff wrote:
> >>> On Mon, Nov 03, 2014 at 11:39:00AM -0800, Jarno Rajahalme wrote:
> >>>> Returning const struct cls_rule pointers from the classifier API helps
> >>>> callers to remember that they should not modify the rules returned.
> >>>> 
> >>>> Signed-off-by: Jarno Rajahalme <jrajahalme at nicira.com>
> >>> 
> >>> I don't think it has much practical effect since most of the callers
> >>> immediately cast the pointer to some other container type, but it does
> >>> seem a little nicer.
> >>> 
> >>> Acked-by: Ben Pfaff <blp at nicira.com>
> >> 
> >> But you'll need to fix up ovs-router.c, which I think is new since you
> >> posted this.  It has some build failures (GCC and sparse output
> >> interleaved below):
> >> 
> >> ../lib/ovs-router.c:142:8: warning: incorrect type in assignment (different modifiers)
> >> ../lib/ovs-router.c:142:8:    expected struct cls_rule *cr
> >> ../lib/ovs-router.c:142:8:    got struct cls_rule const *
> >> ../lib/ovs-router.c:145:12: warning: incorrect type in assignment (different modifiers)
> >> ../lib/ovs-router.c:145:12:    expected struct cls_rule *cr
> >> ../lib/ovs-router.c:145:12:    got struct cls_rule const *
> >> ../lib/ovs-router.c: In function 'rt_entry_delete':
> >> ../lib/ovs-router.c:142:8: error: assignment discards 'const' qualifier from pointer target type [-Werror]
> >>     cr = classifier_find_rule_exactly(&cls, &rule);
> >>        ^
> >> ../lib/ovs-router.c:145:12: error: assignment discards 'const' qualifier from pointer target type [-Werror]
> >>         cr = classifier_remove(&cls, cr);
> >>            ^
> > 
> > And actually the code in question makes one wonder whether we should
> > either abandon this change or make classifier_remove() take a const
> > pointer too:
> > 
> >    cr = classifier_find_rule_exactly(&cls, &rule);
> >    if (cr) {
> >        /* Remove it. */
> >        cr = classifier_remove(&cls, cr);
> >        if (cr) {
> 
> 
> I think I bumped into this myself, making classifier_remove to take a
> const pointer works, so that’s what I’d like to do.

Fine with me, thanks.