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, 8 insertions, 14 deletions

diff --git a/sys/pc98/cbus/olpt.c b/sys/pc98/cbus/olpt.c
index cd64512..a2c7fe6 100644
--- a/sys/pc98/cbus/olpt.c
+++ b/sys/pc98/cbus/olpt.c
@@ -1161,18 +1161,15 @@ lpintr (int unit)
 
 	    sc->sc_iferrs = 0;
 
-	    if (IF_QFULL(&ipintrq)) {
-	        lprintf(("DROP"));
-	        IF_DROP(&ipintrq);
-		goto done;
-	    }
 	    len -= CLPIPHDRLEN;
 	    sc->sc_if.if_ipackets++;
 	    sc->sc_if.if_ibytes += len;
 	    top = m_devget(sc->sc_ifbuf + CLPIPHDRLEN, len, 0, &sc->sc_if, 0);
 	    if (top) {
-	        IF_ENQUEUE(&ipintrq, top);
-	        schednetisr(NETISR_IP);
+	        if (! IF_HANDOFF(&ipintrq, top, NULL))
+	            lprintf(("DROP"));
+                else
+	            schednetisr(NETISR_IP);
 	    }
 	    goto done;
 	}
@@ -1210,11 +1207,6 @@ lpintr (int unit)
 
 	    sc->sc_iferrs = 0;
 
-	    if (IF_QFULL(&ipintrq)) {
-		lprintf(("DROP"));
-		IF_DROP(&ipintrq);
-		goto done;
-	    }
 	    if (sc->sc_if.if_bpf) {
 		bpf_tap(&sc->sc_if, sc->sc_ifbuf, len);
 	    }
@@ -1223,8 +1215,10 @@ lpintr (int unit)
 	    sc->sc_if.if_ibytes += len;
 	    top = m_devget(sc->sc_ifbuf + LPIPHDRLEN, len, 0, &sc->sc_if, 0);
 	    if (top) {
-		    IF_ENQUEUE(&ipintrq, top);
-		    schednetisr(NETISR_IP);
+	        if (! IF_HANDOFF(&ipintrq, top, NULL))
+	            lprintf(("DROP"));
+                else
+	            schednetisr(NETISR_IP);
 	    }
 	}
 	goto done;