Acquire submit queue mutex only once per xbf_complete_cmd invocation

and remove some leftover assertions.

diff --git a/sys/dev/pv/xbf.c b/sys/dev/pv/xbf.c
index 8c4b8df..375ceed 100644 (file)
--- a/sys/dev/pv/xbf.c
+++ b/sys/dev/pv/xbf.c
@@ -1,7 +1,7 @@
-/*     $OpenBSD: xbf.c,v 1.30 2017/06/06 21:12:01 mikeb Exp $  */
+/*     $OpenBSD: xbf.c,v 1.31 2017/06/07 15:49:21 mikeb Exp $  */
 
 /*
- * Copyright (c) 2016 Mike Belopuhov
+ * Copyright (c) 2016, 2017 Mike Belopuhov
  * Copyright (c) 2009, 2011 Mark Kettenis
  *
  * Permission to use, copy, modify, and distribute this software for any
@@ -507,7 +507,6 @@ xbf_load_cmd(struct scsi_xfer *xs)
                KASSERT(sge->sge_last <= 7);
        }
 
-       KASSERT(nsg > 0);
        xrd->xrd_req.req_nsegs = nsg;
 
        return (0);
@@ -698,8 +697,6 @@ xbf_submit_cmd(struct scsi_xfer *xs)
                if (error)
                        return (-1);
        } else {
-               KASSERT(nblk == 0);
-               KASSERT(ndesc == 1);
                DPRINTF("%s: desc %u %s%s lba %llu\n", sc->sc_dev.dv_xname,
                    ccb->ccb_first, operation == XBF_OP_FLUSH ? "flush" :
                    "barrier", ISSET(xs->flags, SCSI_POLL) ? "-poll" : "",
@@ -757,37 +754,36 @@ xbf_complete_cmd(struct xbf_softc *sc, struct xbf_ccb_queue *cq, int desc)
        uint32_t id, chunk;
        int error;
 
-       bus_dmamap_sync(sc->sc_dmat, sc->sc_xr_dma.dma_map, 0,
-           sc->sc_xr_dma.dma_map->dm_mapsize, BUS_DMASYNC_POSTREAD |
-           BUS_DMASYNC_POSTWRITE);
-
        xrd = &sc->sc_xr->xr_desc[desc];
        error = xrd->xrd_rsp.rsp_status == XBF_OK ? XS_NOERROR :
            XS_DRIVER_STUFFUP;
 
-       id = (uint32_t)xrd->xrd_rsp.rsp_id;
        mtx_enter(&sc->sc_ccb_sqlck);
+
+       /*
+        * To find a CCB for id equal to x within an interval [a, b] we must
+        * locate a CCB such that (x - a) mod N <= (b - a) mod N, where a is
+        * the first descriptor, b is the last one and N is the ring size.
+        */
+       id = (uint32_t)xrd->xrd_rsp.rsp_id;
        TAILQ_FOREACH(ccb, &sc->sc_ccb_sq, ccb_link) {
                if (((id - ccb->ccb_first) & (sc->sc_xr_ndesc - 1)) <=
                    ((ccb->ccb_last - ccb->ccb_first) & (sc->sc_xr_ndesc - 1)))
                        break;
        }
-       mtx_leave(&sc->sc_ccb_sqlck);
        KASSERT(ccb != NULL);
+
+       /* Assert that this chunk belongs to this CCB */
        chunk = 1 << ((id - ccb->ccb_first) & (sc->sc_xr_ndesc - 1));
-#ifdef XBF_DEBUG
-       if ((ccb->ccb_want & chunk) == 0) {
-               panic("%s: id %#x first %#x want %#x seen %#x chunk %#x",
-                   sc->sc_dev.dv_xname, id, ccb->ccb_first, ccb->ccb_want,
-                   ccb->ccb_seen, chunk);
-       }
-       if ((ccb->ccb_seen & chunk) != 0) {
-               panic("%s: id %#x first %#x want %#x seen %#x chunk %#x",
-                   sc->sc_dev.dv_xname, id, ccb->ccb_first, ccb->ccb_want,
-                   ccb->ccb_seen, chunk);
-       }
-#endif
+       KASSERT((ccb->ccb_want & chunk) != 0);
+       KASSERT((ccb->ccb_seen & chunk) == 0);
+
+       /* When all chunks are collected remove the CCB from the queue */
        ccb->ccb_seen |= chunk;
+       if (ccb->ccb_seen == ccb->ccb_want)
+               TAILQ_REMOVE(&sc->sc_ccb_sq, ccb, ccb_link);
+
+       mtx_leave(&sc->sc_ccb_sqlck);
 
        if (ccb->ccb_bbuf.dma_size > 0)
                map = ccb->ccb_bbuf.dma_map;
@@ -806,10 +802,6 @@ xbf_complete_cmd(struct xbf_softc *sc, struct xbf_ccb_queue *cq, int desc)
        xrd->xrd_req.req_id = desc;
 
        if (ccb->ccb_seen == ccb->ccb_want) {
-               mtx_enter(&sc->sc_ccb_sqlck);
-               TAILQ_REMOVE(&sc->sc_ccb_sq, ccb, ccb_link);
-               mtx_leave(&sc->sc_ccb_sqlck);
-
                ccb->ccb_xfer->resid = 0;
                ccb->ccb_xfer->error = error;
                TAILQ_INSERT_TAIL(cq, ccb, ccb_link);
@@ -900,8 +892,6 @@ xbf_scsi_done(struct scsi_xfer *xs, int error)
 {
        int s;
 
-       KERNEL_ASSERT_LOCKED();
-
        xs->error = error;
 
        s = splbio();
@@ -912,8 +902,6 @@ xbf_scsi_done(struct scsi_xfer *xs, int error)
 int
 xbf_dev_probe(struct scsi_link *link)
 {
-       KASSERT(link->lun == 0);
-
        if (link->target == 0)
                return (0);