svn commit: r324156 - head/sys/dev/smbus

[Konstantin Belousov]

Author: kib
Date: Sun Oct  1 11:17:30 2017
New Revision: 324156
URL: https://svnweb.freebsd.org/changeset/base/324156

Log:
  Improve smb(4) devfs interactions.
  
  Use make_dev_s(9) to create device, since the device ioctl interface
  needs to access si_drv1 to get softc pointer.
  
  Remove the common but not functional attempt to prevent parallel
  accesses by file descriptors by blocking more than one open.  Either
  threads in one process, or forked siblings, or file descriptors passed
  over unix domain sockets all allow to execute parallel requests once
  one fd is opened.  Since ioctl handler uses smbus_request_bus() to
  take the bus ownership, the correct mechanism establishes exclusive
  access already.
  
  Sponsored by:	The FreeBSD Foundation
  MFC after:	2 weeks

Modified:
  head/sys/dev/smbus/smb.c

Modified: head/sys/dev/smbus/smb.c
==============================================================================
--- head/sys/dev/smbus/smb.c	Sun Oct  1 09:48:31 2017	(r324155)
+++ head/sys/dev/smbus/smb.c	Sun Oct  1 11:17:30 2017	(r324156)
@@ -47,9 +47,7 @@
 
 struct smb_softc {
 	device_t sc_dev;
-	int sc_count;			/* >0 if device opened */
 	struct cdev *sc_devnode;
-	struct mtx sc_lock;
 };
 
 static void smb_identify(driver_t *driver, device_t parent);
@@ -78,15 +76,11 @@ static driver_t smb_driver = {
 	sizeof(struct smb_softc),
 };
 
-static	d_open_t	smbopen;
-static	d_close_t	smbclose;
 static	d_ioctl_t	smbioctl;
 
 static struct cdevsw smb_cdevsw = {
 	.d_version =	D_VERSION,
 	.d_flags =	D_TRACKCLOSE,
-	.d_open =	smbopen,
-	.d_close =	smbclose,
 	.d_ioctl =	smbioctl,
 	.d_name =	"smb",
 };
@@ -112,59 +106,31 @@ smb_probe(device_t dev)
 static int
 smb_attach(device_t dev)
 {
-	struct smb_softc *sc = device_get_softc(dev);
-	int unit;
-	
-	unit = device_get_unit(dev);
+	struct smb_softc *sc;
+	struct make_dev_args mda;
+	int error;
+
+	sc = device_get_softc(dev);
 	sc->sc_dev = dev;
 
-	sc->sc_devnode = make_dev(&smb_cdevsw, unit, UID_ROOT, GID_WHEEL,
-	    0600, "smb%d", unit);
-	sc->sc_devnode->si_drv1 = sc;
-	mtx_init(&sc->sc_lock, device_get_nameunit(dev), NULL, MTX_DEF);
-
-	return (0);
+	make_dev_args_init(&mda);
+	mda.mda_devsw = &smb_cdevsw;
+	mda.mda_unit = device_get_unit(dev);
+	mda.mda_uid = UID_ROOT;
+	mda.mda_gid = GID_WHEEL;
+	mda.mda_mode = 0600;
+	mda.mda_si_drv1 = sc;
+	error = make_dev_s(&mda, &sc->sc_devnode, "smb%d", mda.mda_unit);
+	return (error);
 }
 
 static int
 smb_detach(device_t dev)
 {
-	struct smb_softc *sc = (struct smb_softc *)device_get_softc(dev);
+	struct smb_softc *sc;
 
-	if (sc->sc_devnode)
-		destroy_dev(sc->sc_devnode);
-	mtx_destroy(&sc->sc_lock);
-
-	return (0);
-}
-
-static int
-smbopen(struct cdev *dev, int flags, int fmt, struct thread *td)
-{
-	struct smb_softc *sc = dev->si_drv1;
-
-	mtx_lock(&sc->sc_lock);
-	if (sc->sc_count != 0) {
-		mtx_unlock(&sc->sc_lock);
-		return (EBUSY);
-	}
-
-	sc->sc_count++;
-	mtx_unlock(&sc->sc_lock);
-
-	return (0);
-}
-
-static int
-smbclose(struct cdev *dev, int flags, int fmt, struct thread *td)
-{
-	struct smb_softc *sc = dev->si_drv1;
-
-	mtx_lock(&sc->sc_lock);
-	KASSERT(sc->sc_count == 1, ("device not busy"));
-	sc->sc_count--;
-	mtx_unlock(&sc->sc_lock);
-
+	sc = device_get_softc(dev);
+	destroy_dev(sc->sc_devnode);
 	return (0);
 }