From 1a13e40f03702e475fa0d210faf9614fbaf8cdef Mon Sep 17 00:00:00 2001
From: jhb <jhb@FreeBSD.org>
Date: Thu, 1 Nov 2018 21:39:33 +0000
Subject: [PATCH] Assert that reclaim_tx_descs() is always making forward
 progress.

MFC after:	2 months
Sponsored by:	Chelsio Communications
---
 sys/dev/cxgbe/t4_sge.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/sys/dev/cxgbe/t4_sge.c b/sys/dev/cxgbe/t4_sge.c
index 9b0e2628b235..a9120a036056 100644
--- a/sys/dev/cxgbe/t4_sge.c
+++ b/sys/dev/cxgbe/t4_sge.c
@@ -5079,6 +5079,9 @@ reclaim_tx_descs(struct sge_txq *txq, u_int n)
 		KASSERT(can_reclaim >= ndesc,
 		    ("%s: unexpected number of credits: %d, %d",
 		    __func__, can_reclaim, ndesc));
+		KASSERT(ndesc != 0,
+		    ("%s: descriptor with no credits: cidx %d",
+		    __func__, eq->cidx));
 
 		for (m = txsd->m; m != NULL; m = nextpkt) {
 			nextpkt = m->m_nextpkt;