Lock down the network interface queues. The queue mutex must be obtained

before adding/removing packets from the queue.  Also, the if_obytes and
if_omcasts fields should only be manipulated under protection of the mutex.

IF_ENQUEUE, IF_PREPEND, and IF_DEQUEUE perform all necessary locking on
the queue.  An IF_LOCK macro is provided, as well as the old (mutex-less)
versions of the macros in the form _IF_ENQUEUE, _IF_QFULL, for code which
needs them, but their use is discouraged.

Two new macros are introduced: IF_DRAIN() to drain a queue, and IF_HANDOFF,
which takes care of locking/enqueue, and also statistics updating/start
if necessary.

1 files changed, 3 insertions, 15 deletions

diff --git a/sys/net/if_ef.c b/sys/net/if_ef.c
index ad28d5d..f8e38ca 100644
--- a/sys/net/if_ef.c
+++ b/sys/net/if_ef.c
@@ -234,17 +234,11 @@ ef_start(struct ifnet *ifp)
 			break;
 		if (ifp->if_bpf)
 			bpf_mtap(ifp, m);
-		if (IF_QFULL(&p->if_snd)) {
-			IF_DROP(&p->if_snd);
+		if (! IF_HANDOFF(&p->if_snd, m, NULL)) {
 			ifp->if_oerrors++;
-			m_freem(m);
 			continue;
 		}
-		IF_ENQUEUE(&p->if_snd, m);
-		if ((p->if_flags & IFF_OACTIVE) == 0) {
-			p->if_start(p);
-			ifp->if_opackets++;
-		}
+		ifp->if_opackets++;
 	}
 	ifp->if_flags &= ~IFF_OACTIVE;
 	return;
@@ -419,13 +413,7 @@ ef_input(struct ifnet *ifp, struct ether_header *eh, struct mbuf *m)
 			ft, ether_type);
 		return EPROTONOSUPPORT;
 	}
-	s = splimp();
-	if (IF_QFULL(inq)) {
-		IF_DROP(inq);
-		m_freem(m);
-	} else
-		IF_ENQUEUE(inq, m);
-	splx(s);
+	(void) IF_HANDOFF(inq, m, NULL);
 	return 0;
 }