From dcbc025ff1395ef0b673db99d4509b8fe746ab61 Mon Sep 17 00:00:00 2001
From: Sean Bruno <sbruno@FreeBSD.org>
Date: Wed, 19 Jul 2017 21:18:04 +0000
Subject: [PATCH] Don't cache mbuf pointers if the number of descriptors is
 greater than the number of buffers.

Submitted by:	Matt Macy <mmacy@mattmacy.io>
Sponsored by:	Limelight Networks
---
 sys/net/iflib.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/sys/net/iflib.c b/sys/net/iflib.c
index 633ebc9668ba..2ec1dadef32c 100644
--- a/sys/net/iflib.c
+++ b/sys/net/iflib.c
@@ -2927,6 +2927,14 @@ iflib_busdma_load_mbuf_sg(iflib_txq_t txq, bus_dma_tag_t tag, bus_dmamap_t map,
 				m_free(tmp);
 				continue;
 			}
+			m = m->m_next;
+			count++;
+		} while (m != NULL);
+		if (count > *nsegs)
+			return (0);
+		m = *m0;
+		count = 0;
+		do {
 			next = (pidx + count) & (ntxd-1);
 			MPASS(ifsd_m[next] == NULL);
 			ifsd_m[next] = m;