From: jmatthew <jmatthew@openbsd.org>
Date: Tue, 9 Feb 2021 01:50:10 +0000 (+0000)
Subject: Add a barrier between reading the cqe flags and the command ID, which
X-Git-Url: http://artulab.com/gitweb/?a=commitdiff_plain;h=ee570821402ebda8e6230e9e2035c8409933bfc1;p=openbsd

Add a barrier between reading the cqe flags and the command ID, which
should ensure that we don't read a stale command ID and complete the
wrong scsi io.  powerpc64 base builds were crashing like this fairly
regularly.

ok deraadt@ dlg@
---

diff --git a/sys/dev/ic/nvme.c b/sys/dev/ic/nvme.c
index 2d0168899c3..602f93d1fb3 100644
--- a/sys/dev/ic/nvme.c
+++ b/sys/dev/ic/nvme.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: nvme.c,v 1.89 2020/10/15 13:22:13 krw Exp $ */
+/*	$OpenBSD: nvme.c,v 1.90 2021/02/09 01:50:10 jmatthew Exp $ */
 
 /*
  * Copyright (c) 2014 David Gwynne <dlg@openbsd.org>
@@ -994,6 +994,8 @@ nvme_q_complete(struct nvme_softc *sc, struct nvme_queue *q)
 		if ((flags & NVME_CQE_PHASE) != q->q_cq_phase)
 			break;
 
+		membar_consumer();
+
 		ccb = &sc->sc_ccbs[cqe->cid];
 		ccb->ccb_done(sc, ccb, cqe);