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[src/trunk]: src/sys/dev/dkwedge Make dk(4) device mpsafe.
details: https://anonhg.NetBSD.org/src/rev/6030bcb5cb70
branches: trunk
changeset: 819763:6030bcb5cb70
user: mlelstv <mlelstv%NetBSD.org@localhost>
date: Fri Dec 16 15:06:39 2016 +0000
description:
Make dk(4) device mpsafe.
diffstat:
sys/dev/dkwedge/dk.c | 84 ++++++++++++++++++++++++++++++++++-----------------
1 files changed, 56 insertions(+), 28 deletions(-)
diffs (259 lines):
diff -r e551c7f38cf3 -r 6030bcb5cb70 sys/dev/dkwedge/dk.c
--- a/sys/dev/dkwedge/dk.c Fri Dec 16 15:00:52 2016 +0000
+++ b/sys/dev/dkwedge/dk.c Fri Dec 16 15:06:39 2016 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: dk.c,v 1.91 2016/05/29 13:11:21 mlelstv Exp $ */
+/* $NetBSD: dk.c,v 1.92 2016/12/16 15:06:39 mlelstv Exp $ */
/*-
* Copyright (c) 2004, 2005, 2006, 2007 The NetBSD Foundation, Inc.
@@ -30,7 +30,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: dk.c,v 1.91 2016/05/29 13:11:21 mlelstv Exp $");
+__KERNEL_RCSID(0, "$NetBSD: dk.c,v 1.92 2016/12/16 15:06:39 mlelstv Exp $");
#ifdef _KERNEL_OPT
#include "opt_dkwedge.h"
@@ -86,8 +86,10 @@
struct bufq_state *sc_bufq; /* buffer queue */
struct callout sc_restart_ch; /* callout to restart I/O */
+ kmutex_t sc_iolock;
+ kcondvar_t sc_dkdrn;
u_int sc_iopend; /* I/Os pending */
- int sc_flags; /* flags (splbio) */
+ int sc_flags; /* flags (sc_iolock) */
};
#define DK_F_WAIT_DRAIN 0x0001 /* waiting for I/O to drain */
@@ -123,7 +125,7 @@
.d_dump = dkdump,
.d_psize = dksize,
.d_discard = dkdiscard,
- .d_flag = D_DISK
+ .d_flag = D_DISK | D_MPSAFE
};
const struct cdevsw dk_cdevsw = {
@@ -138,7 +140,7 @@
.d_mmap = nommap,
.d_kqfilter = nokqfilter,
.d_discard = dkdiscard,
- .d_flag = D_DISK
+ .d_flag = D_DISK | D_MPSAFE
};
static struct dkwedge_softc **dkwedges;
@@ -185,16 +187,17 @@
* dkwedge_wait_drain:
*
* Wait for I/O on the wedge to drain.
- * NOTE: Must be called at splbio()!
*/
static void
dkwedge_wait_drain(struct dkwedge_softc *sc)
{
+ mutex_enter(&sc->sc_iolock);
while (sc->sc_iopend != 0) {
sc->sc_flags |= DK_F_WAIT_DRAIN;
- (void) tsleep(&sc->sc_iopend, PRIBIO, "dkdrn", 0);
+ cv_wait(&sc->sc_dkdrn, &sc->sc_iolock);
}
+ mutex_exit(&sc->sc_iolock);
}
/*
@@ -325,6 +328,9 @@
callout_init(&sc->sc_restart_ch, 0);
callout_setfunc(&sc->sc_restart_ch, dkrestart, sc);
+ mutex_init(&sc->sc_iolock, MUTEX_DEFAULT, IPL_BIO);
+ cv_init(&sc->sc_dkdrn, "dkdrn");
+
/*
* Wedge will be added; increment the wedge count for the parent.
* Only allow this to happend if RAW_PART is the only thing open.
@@ -568,7 +574,7 @@
{
struct dkwedge_softc *sc = NULL;
u_int unit;
- int bmaj, cmaj, rc, s;
+ int bmaj, cmaj, rc;
rw_enter(&dkwedges_lock, RW_WRITER);
for (unit = 0; unit < ndkwedges; unit++) {
@@ -600,10 +606,8 @@
* state of the wedge is not RUNNING. Once we've done
* that, wait for any other pending I/O to complete.
*/
- s = splbio();
dkstart(sc);
dkwedge_wait_drain(sc);
- splx(s);
/* Nuke the vnodes for any open instances. */
vdevgone(bmaj, unit, unit, VBLK);
@@ -635,6 +639,9 @@
sc->sc_state = DKW_STATE_DEAD;
rw_exit(&dkwedges_lock);
+ mutex_destroy(&sc->sc_iolock);
+ cv_destroy(&sc->sc_dkdrn);
+
free(sc, M_DKWEDGE);
return 0;
@@ -1206,7 +1213,6 @@
{
struct dkwedge_softc *sc = dkwedge_lookup(bp->b_dev);
uint64_t p_size, p_offset;
- int s;
if (sc == NULL) {
bp->b_error = ENODEV;
@@ -1234,11 +1240,12 @@
bp->b_rawblkno = bp->b_blkno + p_offset;
/* Place it in the queue and start I/O on the unit. */
- s = splbio();
+ mutex_enter(&sc->sc_iolock);
sc->sc_iopend++;
bufq_put(sc->sc_bufq, bp);
+ mutex_exit(&sc->sc_iolock);
+
dkstart(sc);
- splx(s);
return;
done:
@@ -1250,7 +1257,6 @@
* dkstart:
*
* Start I/O that has been enqueued on the wedge.
- * NOTE: Must be called at splbio()!
*/
static void
dkstart(struct dkwedge_softc *sc)
@@ -1258,36 +1264,58 @@
struct vnode *vp;
struct buf *bp, *nbp;
+ mutex_enter(&sc->sc_iolock);
+
/* Do as much work as has been enqueued. */
while ((bp = bufq_peek(sc->sc_bufq)) != NULL) {
+
if (sc->sc_state != DKW_STATE_RUNNING) {
(void) bufq_get(sc->sc_bufq);
if (sc->sc_iopend-- == 1 &&
(sc->sc_flags & DK_F_WAIT_DRAIN) != 0) {
sc->sc_flags &= ~DK_F_WAIT_DRAIN;
- wakeup(&sc->sc_iopend);
+ cv_broadcast(&sc->sc_dkdrn);
}
+ mutex_exit(&sc->sc_iolock);
bp->b_error = ENXIO;
bp->b_resid = bp->b_bcount;
biodone(bp);
+ mutex_enter(&sc->sc_iolock);
+ continue;
}
- /* Instrumentation. */
- disk_busy(&sc->sc_dk);
-
+ /* fetch an I/O buf with sc_iolock dropped */
+ mutex_exit(&sc->sc_iolock);
nbp = getiobuf(sc->sc_parent->dk_rawvp, false);
+ mutex_enter(&sc->sc_iolock);
if (nbp == NULL) {
/*
* No resources to run this request; leave the
* buffer queued up, and schedule a timer to
* restart the queue in 1/2 a second.
*/
- disk_unbusy(&sc->sc_dk, 0, bp->b_flags & B_READ);
callout_schedule(&sc->sc_restart_ch, hz / 2);
- return;
+ break;
}
- (void) bufq_get(sc->sc_bufq);
+ /*
+ * fetch buf, this can fail if another thread
+ * has already processed the queue, it can also
+ * return a completely different buf.
+ */
+ bp = bufq_get(sc->sc_bufq);
+ if (bp == NULL) {
+ mutex_exit(&sc->sc_iolock);
+ putiobuf(nbp);
+ mutex_enter(&sc->sc_iolock);
+ continue;
+ }
+
+ /* Instrumentation. */
+ disk_busy(&sc->sc_dk);
+
+ /* release lock for VOP_STRATEGY */
+ mutex_exit(&sc->sc_iolock);
nbp->b_data = bp->b_data;
nbp->b_flags = bp->b_flags;
@@ -1308,7 +1336,11 @@
mutex_exit(vp->v_interlock);
}
VOP_STRATEGY(vp, nbp);
+
+ mutex_enter(&sc->sc_iolock);
}
+
+ mutex_exit(&sc->sc_iolock);
}
/*
@@ -1322,26 +1354,25 @@
struct buf *obp = bp->b_private;
struct dkwedge_softc *sc = dkwedge_lookup(obp->b_dev);
- int s = splbio();
-
if (bp->b_error != 0)
obp->b_error = bp->b_error;
obp->b_resid = bp->b_resid;
putiobuf(bp);
+ mutex_enter(&sc->sc_iolock);
if (sc->sc_iopend-- == 1 && (sc->sc_flags & DK_F_WAIT_DRAIN) != 0) {
sc->sc_flags &= ~DK_F_WAIT_DRAIN;
- wakeup(&sc->sc_iopend);
+ cv_broadcast(&sc->sc_dkdrn);
}
disk_unbusy(&sc->sc_dk, obp->b_bcount - obp->b_resid,
obp->b_flags & B_READ);
+ mutex_exit(&sc->sc_iolock);
biodone(obp);
/* Kick the queue in case there is more work we can do. */
dkstart(sc);
- splx(s);
}
/*
@@ -1354,11 +1385,8 @@
dkrestart(void *v)
{
struct dkwedge_softc *sc = v;
- int s;
- s = splbio();
dkstart(sc);
- splx(s);
}
/*
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