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Improve smb(4) devfs interactions.

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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
This commit is contained in:
Konstantin Belousov 2017-10-01 11:17:30 +00:00
parent 21811c24c6
commit 68b2efbd3b
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=324156
1 changed files with 17 additions and 51 deletions
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68
sys/dev/smbus/smb.c
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@ -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);
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);
struct smb_softc *sc;
sc = device_get_softc(dev);
destroy_dev(sc->sc_devnode);
return (0);
}