Calculate the RSS hash for outbound UDPv4 frames.

Differential Revision:	https://reviews.freebsd.org/D527
Reviewed by:	grehan

1 files changed, 45 insertions, 0 deletions

diff --git a/sys/netinet/udp_usrreq.c b/sys/netinet/udp_usrreq.c
index ecb7aec8d889..584f390e9d3b 100644
--- a/sys/netinet/udp_usrreq.c
+++ b/sys/netinet/udp_usrreq.c
@@ -90,6 +90,7 @@ __FBSDID("$FreeBSD$");
 #include <netinet/udp.h>
 #include <netinet/udp_var.h>
 #include <netinet/udplite.h>
+#include <netinet/in_rss.h>
 
 #ifdef IPSEC
 #include <netipsec/ipsec.h>
@@ -207,6 +208,13 @@ void
 udp_init(void)
 {
 
+	/*
+	 * For now default to 2-tuple UDP hashing - until the fragment
+	 * reassembly code can also update the flowid.
+	 *
+	 * Once we can calculate the flowid that way and re-establish
+	 * a 4-tuple, flip this to 4-tuple.
+	 */
 	in_pcbinfo_init(&V_udbinfo, "udp", &V_udb, UDBHASHSIZE, UDBHASHSIZE,
 	    "udp_inpcb", udp_inpcb_init, NULL, UMA_ZONE_NOFREE,
 	    IPI_HASHFIELDS_2TUPLE);
@@ -1435,9 +1443,46 @@ udp_output(struct inpcb *inp, struct mbuf *m, struct sockaddr *addr,
 		m->m_flags |= M_FLOWID;
 		m->m_pkthdr.flowid = flowid;
 		M_HASHTYPE_SET(m, flowid_type);
+#ifdef	RSS
+	} else {
+		uint32_t hash_val, hash_type;
+		/*
+		 * Calculate an appropriate RSS hash for UDP and
+		 * UDP Lite.
+		 *
+		 * The called function will take care of figuring out
+		 * whether a 2-tuple or 4-tuple hash is required based
+		 * on the currently configured scheme.
+		 *
+		 * Later later on connected socket values should be
+		 * cached in the inpcb and reused, rather than constantly
+		 * re-calculating it.
+		 *
+		 * UDP Lite is a different protocol number and will
+		 * likely end up being hashed as a 2-tuple until
+		 * RSS / NICs grow UDP Lite protocol awareness.
+		 */
+		if (rss_proto_software_hash_v4(faddr, laddr, fport, lport,
+		    pr, &hash_val, &hash_type) == 0) {
+			m->m_pkthdr.flowid = hash_val;
+			m->m_flags |= M_FLOWID;
+			M_HASHTYPE_SET(m, hash_type);
+		}
+#endif
 	}
 
 #ifdef	RSS
+	/*
+	 * Don't override with the inp cached flowid value.
+	 *
+	 * Depending upon the kind of send being done, the inp
+	 * flowid/flowtype values may actually not be appropriate
+	 * for this particular socket send.
+	 *
+	 * We should either leave the flowid at zero (which is what is
+	 * currently done) or set it to some software generated
+	 * hash value based on the packet contents.
+	 */
 	ipflags |= IP_NODEFAULTFLOWID;
 #endif	/* RSS */