switch mpi from using splbio to protect itself over to mutexes.

mpi only needs two mutexes, one for the list of free ccbs, and another to
protect the reply doorbell. the latter is necessary to allow polling for
command completion to work in smp systems.

tested on sas and fc hbas. this diff was written over 2 years ago now with
surprisingly few tweaks to handle changes that have occurred since then.

2 files changed, 83 insertions, 66 deletions

diff --git a/sys/dev/ic/mpi.c b/sys/dev/ic/mpi.c
index 78b9dbc8eee..91f7c931a3b 100644
--- a/sys/dev/ic/mpi.c
+++ b/sys/dev/ic/mpi.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: mpi.c,v 1.124 2009/12/10 00:20:38 chl Exp $ */
+/*	$OpenBSD: mpi.c,v 1.125 2010/01/03 06:15:30 dlg Exp $ */
 
 /*
  * Copyright (c) 2005, 2006, 2009 David Gwynne <dlg@openbsd.org>
@@ -27,6 +27,7 @@
 #include <sys/proc.h>
 #include <sys/malloc.h>
 #include <sys/kernel.h>
+#include <sys/mutex.h>
 #include <sys/rwlock.h>
 #include <sys/sensors.h>
 
@@ -93,9 +94,9 @@ int			mpi_alloc_replies(struct mpi_softc *);
 void			mpi_push_replies(struct mpi_softc *);
 
 void			mpi_start(struct mpi_softc *, struct mpi_ccb *);
-int			mpi_complete(struct mpi_softc *, struct mpi_ccb *, int);
 int			mpi_poll(struct mpi_softc *, struct mpi_ccb *, int);
-int			mpi_reply(struct mpi_softc *, u_int32_t);
+u_int32_t		mpi_pop_mtx_reply(struct mpi_softc *);
+struct mpi_ccb		*mpi_reply(struct mpi_softc *, u_int32_t);
 
 int			mpi_cfg_spi_port(struct mpi_softc *);
 void			mpi_squash_ppr(struct mpi_softc *);
@@ -200,6 +201,8 @@ mpi_attach(struct mpi_softc *sc)
 	struct scsibus_attach_args	saa;
 	struct mpi_ccb			*ccb;
 
+	mtx_init(&sc->sc_reply_mtx, IPL_BIO);
+
 	printf("\n");
 
 	/* disable interrupts */
@@ -815,22 +818,34 @@ mpi_detach(struct mpi_softc *sc)
 
 }
 
+u_int32_t
+mpi_pop_mtx_reply(struct mpi_softc *sc)
+{
+	u_int32_t			reg;
+
+	mtx_enter(&sc->sc_reply_mtx);
+	reg = mpi_pop_reply(sc);
+	mtx_leave(&sc->sc_reply_mtx);
+
+	return (reg);
+}
+
 int
 mpi_intr(void *arg)
 {
 	struct mpi_softc		*sc = arg;
+	struct mpi_ccb			*ccb = NULL;
 	u_int32_t			reg;
-	int				rv = 0;
 
-	while ((reg = mpi_pop_reply(sc)) != 0xffffffff) {
-		mpi_reply(sc, reg);
-		rv = 1;
+	while ((reg = mpi_pop_mtx_reply(sc)) != 0xffffffff) {
+		ccb = mpi_reply(sc, reg);
+		ccb->ccb_done(ccb);
 	}
 
-	return (rv);
+	return ((ccb == NULL) ? 0 : 1);
 }
 
-int
+struct mpi_ccb *
 mpi_reply(struct mpi_softc *sc, u_int32_t reg)
 {
 	struct mpi_ccb			*ccb;
@@ -882,9 +897,7 @@ mpi_reply(struct mpi_softc *sc, u_int32_t reg)
 	ccb->ccb_state = MPI_CCB_READY;
 	ccb->ccb_rcb = rcb;
 
-	ccb->ccb_done(ccb);
-
-	return (id);
+	return (ccb);
 }
 
 struct mpi_dmamem *
@@ -955,6 +968,7 @@ mpi_alloc_ccbs(struct mpi_softc *sc)
 	int				i;
 
 	TAILQ_INIT(&sc->sc_ccb_free);
+	mtx_init(&sc->sc_ccb_mtx, IPL_BIO);
 
 	sc->sc_ccbs = malloc(sizeof(struct mpi_ccb) * sc->sc_maxcmds,
 	    M_DEVBUF, M_WAITOK | M_CANFAIL | M_ZERO);
@@ -1018,17 +1032,15 @@ mpi_get_ccb(struct mpi_softc *sc)
 {
 	struct mpi_ccb			*ccb;
 
+	mtx_enter(&sc->sc_ccb_mtx);
 	ccb = TAILQ_FIRST(&sc->sc_ccb_free);
-	if (ccb == NULL) {
-		DNPRINTF(MPI_D_CCB, "%s: mpi_get_ccb == NULL\n", DEVNAME(sc));
-		return (NULL);
+	if (ccb != NULL) {
+		TAILQ_REMOVE(&sc->sc_ccb_free, ccb, ccb_link);
+		ccb->ccb_state = MPI_CCB_READY;
 	}
+	mtx_leave(&sc->sc_ccb_mtx);
 
-	TAILQ_REMOVE(&sc->sc_ccb_free, ccb, ccb_link);
-
-	ccb->ccb_state = MPI_CCB_READY;
-
-	DNPRINTF(MPI_D_CCB, "%s: mpi_get_ccb %#x\n", DEVNAME(sc), ccb);
+	DNPRINTF(MPI_D_CCB, "%s: mpi_get_ccb %p\n", DEVNAME(sc), ccb);
 
 	return (ccb);
 }
@@ -1036,13 +1048,15 @@ mpi_get_ccb(struct mpi_softc *sc)
 void
 mpi_put_ccb(struct mpi_softc *sc, struct mpi_ccb *ccb)
 {
-	DNPRINTF(MPI_D_CCB, "%s: mpi_put_ccb %#x\n", DEVNAME(sc), ccb);
+	DNPRINTF(MPI_D_CCB, "%s: mpi_put_ccb %p\n", DEVNAME(sc), ccb);
 
 	ccb->ccb_state = MPI_CCB_FREE;
 	ccb->ccb_xs = NULL;
 	ccb->ccb_done = NULL;
 	bzero(ccb->ccb_cmd, MPI_REQUEST_SIZE);
+	mtx_enter(&sc->sc_ccb_mtx);
 	TAILQ_INSERT_TAIL(&sc->sc_ccb_free, ccb, ccb_link);
+	mtx_leave(&sc->sc_ccb_mtx);
 }
 
 int
@@ -1099,45 +1113,56 @@ mpi_start(struct mpi_softc *sc, struct mpi_ccb *ccb)
 }
 
 int
-mpi_complete(struct mpi_softc *sc, struct mpi_ccb *ccb, int timeout)
+mpi_poll(struct mpi_softc *sc, struct mpi_ccb *ccb, int timeout)
 {
+	struct mpi_ccb_list		completed =
+					    TAILQ_HEAD_INITIALIZER(completed);
+	struct mpi_ccb			*nccb = NULL;
 	u_int32_t			reg;
-	int				id = -1;
+	int				rv = 0;
 
-	DNPRINTF(MPI_D_INTR, "%s: mpi_complete timeout %d\n", DEVNAME(sc),
+	DNPRINTF(MPI_D_INTR, "%s: mpi_poll timeout %d\n", DEVNAME(sc),
 	    timeout);
 
+	mtx_enter(&sc->sc_reply_mtx);
+	mpi_start(sc, ccb);
 	do {
 		reg = mpi_pop_reply(sc);
 		if (reg == 0xffffffff) {
-			if (timeout-- == 0)
-				return (1);
+			if (timeout-- == 0) {
+				printf("%s: timeout\n", DEVNAME(sc));
+				rv = 1;
+				goto timeout;
+			}
 
 			delay(1000);
 			continue;
 		}
 
-		id = mpi_reply(sc, reg);
+		nccb = mpi_reply(sc, reg);
 
-	} while (ccb->ccb_id != id);
+		/* 
+		 * The ccb used for event notification can come out of the
+		 * reply doorbell multiple times. Avoid enqueuing it here for
+		 * completion outside the reply mutex since that can screw the
+		 * completed TAILQ up. We know it will not cause new ccbs to be
+		 * generated and issued, so it is safe to complete here.
+		 */
+		if (nccb == sc->sc_evt_ccb)
+			nccb->ccb_done(nccb);
+		else
+			TAILQ_INSERT_TAIL(&completed, nccb, ccb_link);
 
-	return (0);
-}
-
-int
-mpi_poll(struct mpi_softc *sc, struct mpi_ccb *ccb, int timeout)
-{
-	int				error;
-	int				s;
+	} while (ccb != nccb);
+	mtx_leave(&sc->sc_reply_mtx);
 
-	DNPRINTF(MPI_D_CMD, "%s: mpi_poll\n", DEVNAME(sc));
-
-	s = splbio();
-	mpi_start(sc, ccb);
-	error = mpi_complete(sc, ccb, timeout);
-	splx(s);
+timeout:
+	while ((nccb = TAILQ_FIRST(&completed)) != NULL) {
+		TAILQ_REMOVE(&completed, nccb, ccb_link);
+		nccb->ccb_done(nccb);
+	}
 
-	return (error);
+	return (rv);
 }
 
 int
@@ -1167,9 +1192,7 @@ mpi_scsi_cmd(struct scsi_xfer *xs)
 		return (COMPLETE);
 	}
 
-	s = splbio();
 	ccb = mpi_get_ccb(sc);
-	splx(s);
 	if (ccb == NULL)
 		return (NO_CCB);
 
@@ -1225,8 +1248,8 @@ mpi_scsi_cmd(struct scsi_xfer *xs)
 	if (mpi_load_xs(ccb) != 0) {
 		xs->error = XS_DRIVER_STUFFUP;
 		xs->flags |= ITSDONE;
-		s = splbio();
 		mpi_put_ccb(sc, ccb);
+		s = splbio();
 		scsi_done(xs);
 		splx(s);
 		return (COMPLETE);
@@ -1245,9 +1268,7 @@ mpi_scsi_cmd(struct scsi_xfer *xs)
 		return (COMPLETE);
 	}
 
-	s = splbio();
 	mpi_start(sc, ccb);
-	splx(s);
 	return (SUCCESSFULLY_QUEUED);
 }
 
@@ -1259,6 +1280,7 @@ mpi_scsi_cmd_done(struct mpi_ccb *ccb)
 	struct mpi_ccb_bundle		*mcb = ccb->ccb_cmd;
 	bus_dmamap_t			dmap = ccb->ccb_dmamap;
 	struct mpi_msg_scsi_io_error	*sie;
+	int				s;
 
 	if (xs->datalen != 0) {
 		bus_dmamap_sync(sc->sc_dmat, dmap, 0, dmap->dm_mapsize,
@@ -1275,9 +1297,11 @@ mpi_scsi_cmd_done(struct mpi_ccb *ccb)
 
 	if (ccb->ccb_rcb == NULL) {
 		/* no scsi error, we're ok so drop out early */
-		xs->status = SCSI_OK;
 		mpi_put_ccb(sc, ccb);
+		xs->status = SCSI_OK;
+		s = splbio();
 		scsi_done(xs);
+		splx(s);
 		return;
 	}
 
@@ -1363,7 +1387,9 @@ mpi_scsi_cmd_done(struct mpi_ccb *ccb)
 
 	mpi_push_reply(sc, ccb->ccb_rcb->rcb_reply_dva);
 	mpi_put_ccb(sc, ccb);
+	s = splbio();
 	scsi_done(xs);
+	splx(s);
 }
 
 void
@@ -1981,13 +2007,11 @@ mpi_portfacts(struct mpi_softc *sc)
 	struct mpi_ccb				*ccb;
 	struct mpi_msg_portfacts_request	*pfq;
 	volatile struct mpi_msg_portfacts_reply	*pfp;
-	int					s, rv = 1;
+	int					rv = 1;
 
 	DNPRINTF(MPI_D_MISC, "%s: mpi_portfacts\n", DEVNAME(sc));
 
-	s = splbio();
 	ccb = mpi_get_ccb(sc);
-	splx(s);
 	if (ccb == NULL) {
 		DNPRINTF(MPI_D_MISC, "%s: mpi_portfacts ccb_get\n",
 		    DEVNAME(sc));
@@ -2095,11 +2119,8 @@ mpi_eventnotify(struct mpi_softc *sc)
 {
 	struct mpi_ccb				*ccb;
 	struct mpi_msg_event_request		*enq;
-	int					s;
 
-	s = splbio();
 	ccb = mpi_get_ccb(sc);
-	splx(s);
 	if (ccb == NULL) {
 		DNPRINTF(MPI_D_MISC, "%s: mpi_eventnotify ccb_get\n",
 		    DEVNAME(sc));
@@ -2114,6 +2135,7 @@ mpi_eventnotify(struct mpi_softc *sc)
 	enq->event_switch = MPI_EVENT_SWITCH_ON;
 	enq->msg_context = htole32(ccb->ccb_id);
 
+	sc->sc_evt_ccb = ccb;
 	mpi_start(sc, ccb);
 	return (0);
 }
@@ -2256,13 +2278,10 @@ mpi_portenable(struct mpi_softc *sc)
 {
 	struct mpi_ccb				*ccb;
 	struct mpi_msg_portenable_request	*peq;
-	int					s;
 
 	DNPRINTF(MPI_D_MISC, "%s: mpi_portenable\n", DEVNAME(sc));
 
-	s = splbio();
 	ccb = mpi_get_ccb(sc);
-	splx(s);
 	if (ccb == NULL) {
 		DNPRINTF(MPI_D_MISC, "%s: mpi_portenable ccb_get\n",
 		    DEVNAME(sc));
@@ -2303,7 +2322,6 @@ mpi_fwupload(struct mpi_softc *sc)
 	} __packed				*bundle;
 	struct mpi_msg_fwupload_reply		*upp;
 	u_int64_t				addr;
-	int					s;
 	int					rv = 0;
 
 	if (sc->sc_fw_len == 0)
@@ -2318,9 +2336,7 @@ mpi_fwupload(struct mpi_softc *sc)
 		return (1);
 	}
 
-	s = splbio();
 	ccb = mpi_get_ccb(sc);
-	splx(s);
 	if (ccb == NULL) {
 		DNPRINTF(MPI_D_MISC, "%s: mpi_fwupload ccb_get\n",
 		    DEVNAME(sc));
@@ -2462,9 +2478,7 @@ mpi_req_cfg_header(struct mpi_softc *sc, u_int8_t type, u_int8_t number,
 	    "address: 0x%08x flags: 0x%b\n", DEVNAME(sc), type, number,
 	    address, flags, MPI_PG_FMT);
 
-	s = splbio();
 	ccb = mpi_get_ccb(sc);
-	splx(s);
 	if (ccb == NULL) {
 		DNPRINTF(MPI_D_MISC, "%s: mpi_cfg_header ccb_get\n",
 		    DEVNAME(sc));
@@ -2572,9 +2586,7 @@ mpi_req_cfg_page(struct mpi_softc *sc, u_int32_t address, int flags,
 	    len < page_length * 4)
 		return (1);
 
-	s = splbio();
 	ccb = mpi_get_ccb(sc);
-	splx(s);
 	if (ccb == NULL) {
 		DNPRINTF(MPI_D_MISC, "%s: mpi_cfg_page ccb_get\n", DEVNAME(sc));
 		return (1);
diff --git a/sys/dev/ic/mpivar.h b/sys/dev/ic/mpivar.h
index 8db118095e8..4d4f2d8cd33 100644
--- a/sys/dev/ic/mpivar.h
+++ b/sys/dev/ic/mpivar.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: mpivar.h,v 1.25 2009/11/02 23:20:41 marco Exp $ */
+/*	$OpenBSD: mpivar.h,v 1.26 2010/01/03 06:15:30 dlg Exp $ */
 
 /*
  * Copyright (c) 2005 David Gwynne <dlg@openbsd.org>
@@ -111,6 +111,8 @@ struct mpi_softc {
 	bus_size_t		sc_ios;
 	bus_dma_tag_t		sc_dmat;
 
+	struct mutex		sc_reply_mtx;
+
 	u_int8_t		sc_porttype;
 	int			sc_maxcmds;
 	int			sc_maxchdepth;
@@ -125,11 +127,14 @@ struct mpi_softc {
 	struct mpi_dmamem	*sc_requests;
 	struct mpi_ccb		*sc_ccbs;
 	struct mpi_ccb_list	sc_ccb_free;
+	struct mutex		sc_ccb_mtx;
 
 	struct mpi_dmamem	*sc_replies;
 	struct mpi_rcb		*sc_rcbs;
 	int			sc_repq;
 
+	struct mpi_ccb		*sc_evt_ccb;
+
 	size_t			sc_fw_len;
 	struct mpi_dmamem	*sc_fw;