if we get an event notification that requires acknowledgement while

we're busy, we might not be able to allocate a ccb via scsi_ioh_get
if the pool is empty. this means we wont ack the event, which in
turn means we wont receive further event notifications.

this cuts the event ack code over to using a scsi_iohandler. the
eventack iohandler will be called as soon as a ccb becomes available
for it to use. this guarantees reliable event handling and
acknowledgement, despite how busy the controller might be.

this has bugging me ever since i wrote the event handling code.
tested by hotplugging sata disks.

2 files changed, 15 insertions, 21 deletions

diff --git a/sys/dev/ic/mpi.c b/sys/dev/ic/mpi.c
index 845c5413de1..26d4ccf284c 100644
--- a/sys/dev/ic/mpi.c
+++ b/sys/dev/ic/mpi.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: mpi.c,v 1.154 2010/07/06 06:50:42 dlg Exp $ */
+/*	$OpenBSD: mpi.c,v 1.155 2010/07/06 07:18:18 dlg Exp $ */
 
 /*
  * Copyright (c) 2005, 2006, 2009 David Gwynne <dlg@openbsd.org>
@@ -137,8 +137,7 @@ int			mpi_scsi_probe_virtual(struct scsi_link *);
 
 int			mpi_eventnotify(struct mpi_softc *);
 void			mpi_eventnotify_done(struct mpi_ccb *);
-void			mpi_eventack(struct mpi_softc *,
-			    struct mpi_msg_event_reply *);
+void			mpi_eventack(void *, void *);
 void			mpi_eventack_done(struct mpi_ccb *);
 void			mpi_evt_sas(struct mpi_softc *, struct mpi_rcb *);
 
@@ -2191,6 +2190,7 @@ mpi_eventnotify(struct mpi_softc *sc)
 	enq->msg_context = htole32(ccb->ccb_id);
 
 	sc->sc_evt_ccb = ccb;
+	scsi_ioh_set(&sc->sc_evt_ack, &sc->sc_iopool, mpi_eventack, sc);
 	mpi_start(sc, ccb);
 	return (0);
 }
@@ -2239,15 +2239,9 @@ mpi_eventnotify_done(struct mpi_ccb *ccb)
 	}
 
 	if (enp->ack_required)
-		mpi_eventack(sc, enp);
-	mpi_push_reply(sc, ccb->ccb_rcb);
-
-#if 0
-	/* fc hbas have a bad habit of setting this without meaning it. */
-	if ((enp->msg_flags & MPI_EVENT_FLAGS_REPLY_KEPT) == 0) {
-		scsi_io_put(&sc->sc_iopool, ccb);
-	}
-#endif
+		scsi_ioh_add(&sc->sc_evt_ack);
+	else
+		mpi_push_reply(sc, ccb->ccb_rcb);
 }
 
 void
@@ -2293,16 +2287,15 @@ mpi_evt_sas(struct mpi_softc *sc, struct mpi_rcb *rcb)
 }
 
 void
-mpi_eventack(struct mpi_softc *sc, struct mpi_msg_event_reply *enp)
+mpi_eventack(void *cookie, void *io)
 {
-	struct mpi_ccb				*ccb;
+	struct mpi_softc			*sc = cookie;
+	struct mpi_ccb				*ccb = io;
+	struct mpi_ccb				*eccb = sc->sc_evt_ccb;
+	struct mpi_msg_event_reply		*enp = eccb->ccb_rcb->rcb_reply;
 	struct mpi_msg_eventack_request		*eaq;
 
-	ccb = scsi_io_get(&sc->sc_iopool, SCSI_NOSLEEP);
-	if (ccb == NULL) {
-		DNPRINTF(MPI_D_EVT, "%s: mpi_eventack ccb_get\n", DEVNAME(sc));
-		return;
-	}
+	DNPRINTF(MPI_D_EVT, "%s: event ack\n", DEVNAME(sc));
 
 	ccb->ccb_done = mpi_eventack_done;
 	eaq = ccb->ccb_cmd;
@@ -2313,8 +2306,8 @@ mpi_eventack(struct mpi_softc *sc, struct mpi_msg_event_reply *enp)
 	eaq->event = enp->event;
 	eaq->event_context = enp->event_context;
 
+	mpi_push_reply(sc, eccb->ccb_rcb);
 	mpi_start(sc, ccb);
-	return;
 }
 
 void
diff --git a/sys/dev/ic/mpivar.h b/sys/dev/ic/mpivar.h
index b5e43f0251d..eed69bfe6e5 100644
--- a/sys/dev/ic/mpivar.h
+++ b/sys/dev/ic/mpivar.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: mpivar.h,v 1.31 2010/04/06 01:24:43 dlg Exp $ */
+/*	$OpenBSD: mpivar.h,v 1.32 2010/07/06 07:18:18 dlg Exp $ */
 
 /*
  * Copyright (c) 2005 David Gwynne <dlg@openbsd.org>
@@ -134,6 +134,7 @@ struct mpi_softc {
 	int			sc_repq;
 
 	struct mpi_ccb		*sc_evt_ccb;
+	struct scsi_iohandler	sc_evt_ack;
 
 	size_t			sc_fw_len;
 	struct mpi_dmamem	*sc_fw;