svn commit: r355410 - head/sys/geom

[Alexander Motin]

Author: mav
Date: Thu Dec  5 04:03:08 2019
New Revision: 355410
URL: https://svnweb.freebsd.org/changeset/base/355410

Log:
  Switch GEOM_DEV from make_dev_p() to make_dev_s().
  
  It closes the race condition and so allows to remove few NULL checks.
  
  Also while there, use dev->si_drv1 in addition to cp->private to store
  softc pointer.  For calls coming from the dev side it gives reliable cache
  hit instead of often miss before.
  
  MFC after:	2 weeks
  Sponsored by:	iXsystems, Inc.

Modified:
  head/sys/geom/geom_dev.c

Modified: head/sys/geom/geom_dev.c
==============================================================================
--- head/sys/geom/geom_dev.c	Thu Dec  5 02:01:47 2019	(r355409)
+++ head/sys/geom/geom_dev.c	Thu Dec  5 04:03:08 2019	(r355410)
@@ -334,6 +334,7 @@ g_dev_taste(struct g_class *mp, struct g_provider *pp,
 	int error;
 	struct cdev *dev, *adev;
 	char buf[SPECNAMELEN + 6];
+	struct make_dev_args args;
 
 	g_trace(G_T_TOPOLOGY, "dev_taste(%s,%s)", mp->name, pp->name);
 	g_topology_assert();
@@ -346,8 +347,17 @@ g_dev_taste(struct g_class *mp, struct g_provider *pp,
 	error = g_attach(cp, pp);
 	KASSERT(error == 0,
 	    ("g_dev_taste(%s) failed to g_attach, err=%d", pp->name, error));
-	error = make_dev_p(MAKEDEV_CHECKNAME | MAKEDEV_WAITOK, &dev,
-	    &g_dev_cdevsw, NULL, UID_ROOT, GID_OPERATOR, 0640, "%s", gp->name);
+
+	make_dev_args_init(&args);
+	args.mda_flags = MAKEDEV_CHECKNAME | MAKEDEV_WAITOK;
+	args.mda_devsw = &g_dev_cdevsw;
+	args.mda_cr = NULL;
+	args.mda_uid = UID_ROOT;
+	args.mda_gid = GID_OPERATOR;
+	args.mda_mode = 0640;
+	args.mda_si_drv1 = sc;
+	args.mda_si_drv2 = cp;
+	error = make_dev_s(&args, &sc->sc_dev, "%s", gp->name);
 	if (error != 0) {
 		printf("%s: make_dev_p() failed (gp->name=%s, error=%d)\n",
 		    __func__, gp->name, error);
@@ -358,11 +368,9 @@ g_dev_taste(struct g_class *mp, struct g_provider *pp,
 		g_free(sc);
 		return (NULL);
 	}
+	dev = sc->sc_dev;
 	dev->si_flags |= SI_UNMAPPED;
-	sc->sc_dev = dev;
-
 	dev->si_iosize_max = MAXPHYS;
-	dev->si_drv2 = cp;
 	error = init_dumpdev(dev);
 	if (error != 0)
 		printf("%s: init_dumpdev() failed (gp->name=%s, error=%d)\n",
@@ -397,8 +405,6 @@ g_dev_open(struct cdev *dev, int flags, int fmt, struc
 	int error, r, w, e;
 
 	cp = dev->si_drv2;
-	if (cp == NULL)
-		return (ENXIO);		/* g_dev_taste() not done yet */
 	g_trace(G_T_ACCESS, "g_dev_open(%s, %d, %d, %p)",
 	    cp->geom->name, flags, fmt, td);
 
@@ -429,7 +435,7 @@ g_dev_open(struct cdev *dev, int flags, int fmt, struc
 	error = g_access(cp, r, w, e);
 	g_topology_unlock();
 	if (error == 0) {
-		sc = cp->private;
+		sc = dev->si_drv1;
 		mtx_lock(&sc->sc_mtx);
 		if (sc->sc_open == 0 && (sc->sc_active & SC_A_ACTIVE) != 0)
 			wakeup(&sc->sc_active);
@@ -451,8 +457,6 @@ g_dev_close(struct cdev *dev, int flags, int fmt, stru
 	int error, r, w, e;
 
 	cp = dev->si_drv2;
-	if (cp == NULL)
-		return (ENXIO);
 	g_trace(G_T_ACCESS, "g_dev_close(%s, %d, %d, %p)",
 	    cp->geom->name, flags, fmt, td);
 
@@ -477,7 +481,7 @@ g_dev_close(struct cdev *dev, int flags, int fmt, stru
 	if (r + w + e == 0)
 		return (EINVAL);
 
-	sc = cp->private;
+	sc = dev->si_drv1;
 	mtx_lock(&sc->sc_mtx);
 	sc->sc_open += r + w + e;
 	if (sc->sc_open == 0)
@@ -797,7 +801,6 @@ g_dev_strategy(struct bio *bp)
 		("Wrong bio_cmd bio=%p cmd=%d", bp, bp->bio_cmd));
 	dev = bp->bio_dev;
 	cp = dev->si_drv2;
-	sc = cp->private;
 	KASSERT(cp->acr || cp->acw,
 	    ("Consumer with zero access count in g_dev_strategy"));
 	biotrack(bp, __func__);
@@ -809,6 +812,7 @@ g_dev_strategy(struct bio *bp)
 		return;
 	}
 #endif
+	sc = dev->si_drv1;
 	KASSERT(sc->sc_open > 0, ("Closed device in g_dev_strategy"));
 	atomic_add_int(&sc->sc_active, 1);