svn commit: r258328 - head/sys/net

[George V. Neville-Neil]

Author: gnn
Date: Mon Nov 18 22:58:14 2013
New Revision: 258328
URL: http://svnweb.freebsd.org/changeset/base/258328

Log:
  Allow ethernet drivers to pass in packets connected via the nextpkt pointer.
  Handling packets in this way allows drivers to amortize work during packet reception.
  
  Submitted by:	Vijay Singh
  Sponsored by:	NetApp

Modified:
  head/sys/net/if_ethersubr.c

Modified: head/sys/net/if_ethersubr.c
==============================================================================
--- head/sys/net/if_ethersubr.c	Mon Nov 18 22:55:50 2013	(r258327)
+++ head/sys/net/if_ethersubr.c	Mon Nov 18 22:58:14 2013	(r258328)
@@ -708,13 +708,25 @@ static void
 ether_input(struct ifnet *ifp, struct mbuf *m)
 {
 
+	struct mbuf *mn;
+
 	/*
-	 * We will rely on rcvif being set properly in the deferred context,
-	 * so assert it is correct here.
+	 * The drivers are allowed to pass in a chain of packets linked with
+	 * m_nextpkt. We split them up into separate packets here and pass
+	 * them up. This allows the drivers to amortize the receive lock.
 	 */
-	KASSERT(m->m_pkthdr.rcvif == ifp, ("%s: ifnet mismatch", __func__));
+	while (m) {
+		mn = m->m_nextpkt;
+		m->m_nextpkt = NULL;
 
-	netisr_dispatch(NETISR_ETHER, m);
+		/*
+		 * We will rely on rcvif being set properly in the deferred context,
+		 * so assert it is correct here.
+		 */
+		KASSERT(m->m_pkthdr.rcvif == ifp, ("%s: ifnet mismatch", __func__));
+		netisr_dispatch(NETISR_ETHER, m);
+		m = mn;
+	}
 }
 
 /*