1 files changed, 14 insertions, 5 deletions

diff --git a/sys/dev/mps/mps.c b/sys/dev/mps/mps.c
index 77353b184a3e..79558c8a2a08 100644
--- a/sys/dev/mps/mps.c
+++ b/sys/dev/mps/mps.c
@@ -2361,12 +2361,13 @@ void
 mps_intr_locked(void *data)
 {
 	MPI2_REPLY_DESCRIPTORS_UNION *desc;
+	MPI2_DIAG_RELEASE_REPLY *rel_rep;
+	mps_fw_diagnostic_buffer_t *pBuffer;
 	struct mps_softc *sc;
 	struct mps_command *cm = NULL;
+	uint64_t tdesc;
 	uint8_t flags;
 	u_int pq;
-	MPI2_DIAG_RELEASE_REPLY *rel_rep;
-	mps_fw_diagnostic_buffer_t *pBuffer;
 
 	sc = (struct mps_softc *)data;
 
@@ -2378,6 +2379,17 @@ mps_intr_locked(void *data)
 	for ( ;; ) {
 		cm = NULL;
 		desc = &sc->post_queue[sc->replypostindex];
+
+		/*
+		 * Copy and clear out the descriptor so that any reentry will
+		 * immediately know that this descriptor has already been
+		 * looked at.  There is unfortunate casting magic because the
+		 * MPI API doesn't have a cardinal 64bit type.
+		 */
+		tdesc = 0xffffffffffffffff;
+		tdesc = atomic_swap_64((uint64_t *)desc, tdesc);
+		desc = (MPI2_REPLY_DESCRIPTORS_UNION *)&tdesc;
+
 		flags = desc->Default.ReplyFlags &
 		    MPI2_RPY_DESCRIPT_FLAGS_TYPE_MASK;
 		if ((flags == MPI2_RPY_DESCRIPT_FLAGS_UNUSED)
@@ -2496,9 +2508,6 @@ mps_intr_locked(void *data)
 				mps_display_reply_info(sc,cm->cm_reply);
 			mps_complete_command(sc, cm);
 		}
-
-		desc->Words.Low = 0xffffffff;
-		desc->Words.High = 0xffffffff;
 	}
 
 	if (pq != sc->replypostindex) {