On Wed, Apr 28, 2021 at 11:13:05PM +0300, Vitaliy Makkoveev wrote:
> Also we have two cases where `la_mq??? is not empty:
> 1. This thread put it back while performed ifp->if_output
> 2. Concurrent thread put it???s own packet because ARP resolution failed.
>
> So I doubt ???XXXSMP??? and following ???mbuf is back in queue..??? comments
> are
> correct as is. May be it???s better to combine them?
I want to delete this code in next commit and want to replace it
with an assertion. Or do you object this idea?
Which comment should I insert here to delete in next commit?
This diff is about replacing mq_dequeue with mq_delist as sashan@
suggested. The comments are unrelated and are just moved around.
bluhm
> > Index: netinet/if_ether.c
> > ===================================================================
> > RCS file: /data/mirror/openbsd/cvs/src/sys/netinet/if_ether.c,v
> > retrieving revision 1.247
> > diff -u -p -r1.247 if_ether.c
> > --- netinet/if_ether.c 28 Apr 2021 10:33:34 -0000 1.247
> > +++ netinet/if_ether.c 28 Apr 2021 19:35:19 -0000
> > @@ -611,7 +611,9 @@ arpcache(struct ifnet *ifp, struct ether
> > struct in_addr *spa = (struct in_addr *)ea->arp_spa;
> > char addr[INET_ADDRSTRLEN];
> > struct ifnet *rifp;
> > + struct mbuf_list ml;
> > struct mbuf *m;
> > + unsigned int len;
> > int changed = 0;
> >
> > KERNEL_ASSERT_LOCKED();
> > @@ -683,21 +685,17 @@ arpcache(struct ifnet *ifp, struct ether
> >
> > la->la_asked = 0;
> > la->la_refreshed = 0;
> > - while ((m = mq_dequeue(&la->la_mq)) != NULL) {
> > - unsigned int len;
> > -
> > - atomic_dec_int(&la_hold_total);
> > - len = mq_len(&la->la_mq);
> > -
> > + mq_delist(&la->la_mq, &ml);
> > + len = ml_len(&ml);
> > + while ((m = ml_dequeue(&ml)) != NULL) {
> > ifp->if_output(ifp, m, rt_key(rt), rt);
> > -
> > - /* XXXSMP we discard if other CPU enqueues */
> > - if (mq_len(&la->la_mq) > len) {
> > - /* mbuf is back in queue. Discard. */
> > - atomic_sub_int(&la_hold_total, mq_purge(&la->la_mq));
> > - break;
> > - }
> > }
> > + /* XXXSMP we discard if other CPU enqueues */
> > + if (mq_len(&la->la_mq) > 0) {
> > + /* mbuf is back in queue. Discard. */
> > + atomic_sub_int(&la_hold_total, len + mq_purge(&la->la_mq));
> > + } else
> > + atomic_sub_int(&la_hold_total, len);
> >
> > return (0);
> > }
> >
>
