On Mon, Apr 09, 2018 at 11:11:22AM -0600, Theo de Raadt wrote:
> I think this approach is wrong, insane, and fragile. DVF_ACTIVE
> doesn't work precisely that way.
Yes, it's a hack, but i don't see it as fragile, nor insane,
and i agree something better is great, but it does work exactly
as i wanted:
# gpioctl gpio2 attach gpioow 2 1
gpioow0 at gpio2: DATA[2]
onewire0 at gpioow0
# gpioctl gpio2 attach gpioow 4 5
gpioow1 at gpio2: invalid pin mask
gpioow1 detached
# gpioctl gpio2 attach gpioow 4 1
gpioow1 at gpio2: DATA[4]
onewire1 at gpioow1
# gpioctl gpio2 attach gpioow 3 2
gpioow2 at gpio2: can't map pins
gpioow2 detached
# gpioctl gpio2 attach gpioow 3 1
gpioow2 at gpio2: DATA[3]
onewire2 at gpioow2
# gpioctl gpio2 attach gpioow 2 1
gpioow3 at gpio2: can't map pins
gpioow3 detached
^ is with the DVF_ACTIVE-hack,
which does work because at that point it is 'local' to the config_attach(),
and if it does fail it(dv_flags) doesn't exist to cause issues later,
as nothing changes for those who don't call config_defer_failure(),
they will get their DVF_ACTIVE just like before.
my v2.diff below, in case you want to reconsider something like this while
waiting for the whole-tree work to appear:)
-Artturi
diff --git share/man/man9/config_defer.9 share/man/man9/config_defer.9
index ef45867188b..280501a538a 100644
--- share/man/man9/config_defer.9
+++ share/man/man9/config_defer.9
@@ -33,6 +33,7 @@
.Os
.Sh NAME
.Nm config_defer ,
+.Nm config_defer_failure ,
.Nm config_mountroot
.Nd deferred device configuration
.Sh SYNOPSIS
@@ -41,6 +42,8 @@
.Ft "void"
.Fn config_defer "struct device *dev" "void (*func)(struct device *)"
.Ft "void"
+.Fn config_defer_failure "struct device *dev"
+.Ft "void"
.Fn config_mountroot "struct device *dev" "void (*func)(struct device *)"
.Sh DESCRIPTION
The
@@ -53,6 +56,12 @@ is called with the argument
.Fa dev .
.Pp
The
+.Fn config_defer_failure
+function is called by the device to mark its configuration as having
+failed, so it can be detached by
+.Fn config_attach .
+.Pp
+The
.Fn config_mountroot
function is called by a device driver to defer the remainder of its
configuration until after the root file system is mounted.
@@ -60,3 +69,5 @@ At this point, the function
.Fa func
is called with the argument
.Fa dev .
+.Sh SEE ALSO
+.Xr config_attach 9
diff --git sys/dev/gpio/gpioow.c sys/dev/gpio/gpioow.c
index 64d79ab0cb8..912537b7de7 100644
--- sys/dev/gpio/gpioow.c
+++ sys/dev/gpio/gpioow.c
@@ -101,7 +101,7 @@ gpioow_attach(struct device *parent, struct device *self,
void *aux)
/* Check that we have enough pins */
if (gpio_npins(ga->ga_mask) != GPIOOW_NPINS) {
printf(": invalid pin mask\n");
- return;
+ goto fail_nomap;
}
/* Map pins */
@@ -110,7 +110,7 @@ gpioow_attach(struct device *parent, struct device *self,
void *aux)
if (gpio_pin_map(sc->sc_gpio, ga->ga_offset, ga->ga_mask,
&sc->sc_map)) {
printf(": can't map pins\n");
- return;
+ goto fail_nomap;
}
/* Configure data pin */
@@ -153,6 +153,8 @@ gpioow_attach(struct device *parent, struct device *self,
void *aux)
fail:
gpio_pin_unmap(sc->sc_gpio, &sc->sc_map);
+fail_nomap:
+ config_defer_failure(self);
}
int
diff --git sys/kern/subr_autoconf.c sys/kern/subr_autoconf.c
index 3fff153e8ad..e4ff9ee7536 100644
--- sys/kern/subr_autoconf.c
+++ sys/kern/subr_autoconf.c
@@ -409,6 +409,12 @@ config_attach(struct device *parent, void *match, void
*aux, cfprint_t print)
if (--autoconf_attdet == 0)
wakeup(&autoconf_attdet);
mtx_leave(&autoconf_attdet_mtx);
+
+ /* Process deferred failure here by detaching. */
+ if (dev->dv_flags & DVF_FAILED) {
+ if (config_detach(dev, 0) == 0)
+ dev = NULL;
+ }
return (dev);
}
@@ -678,6 +684,18 @@ config_defer(struct device *dev, void (*func)(struct
device *))
config_pending_incr();
}
+/*
+ * Defer the detachment of the specified device with failure
+ * until the end of its own configuration, see config_attach().
+ * XXX "void2int ca_attach()"-churn workaround
+ */
+void
+config_defer_failure(struct device *dev)
+{
+
+ dev->dv_flags |= DVF_FAILED;
+}
+
/*
* Defer the configuration of the specified device until after
* root file system is mounted.
diff --git sys/sys/device.h sys/sys/device.h
index 00a1f6ad2a6..c1d133594ff 100644
--- sys/sys/device.h
+++ sys/sys/device.h
@@ -82,6 +82,7 @@ struct device {
/* dv_flags */
#define DVF_ACTIVE 0x0001 /* device is activated */
+#define DVF_FAILED 0x0002 /* device failed to attach */
TAILQ_HEAD(devicelist, device);
@@ -185,6 +186,7 @@ int config_activate_children(struct device *, int);
struct device *config_make_softc(struct device *parent,
struct cfdata *cf);
void config_defer(struct device *, void (*)(struct device *));
+void config_defer_failure(struct device *);
void config_pending_incr(void);
void config_pending_decr(void);
void config_mountroot(struct device *, void (*)(struct device *));
>
> A better approach would be a whole-tree change such that attach
> functions are non-void. This has been proposed a few times, but
> noone ever sat down and did the whole-tree work.
>
> > could we allow config_attach() to 'fail' without leaving dead device behind?
> > ie. with gpioow(4) it's easy to make a load of these while testing stuff,
> > which does lead to inconsistent unit numbering unless you manually detach
> > the broken ones before attaching another..
> >
> > for devices which are found during autoconf, i guess DETACH_QUIET would
> > be wanted to keep dmesg pretty, as the error messages printed from any
> > ca->ca_attach() should be enough, and would mean no visible change for
> > drivers failing out with this:)
> >
> > for smaller diff i chose to use the DVF_ACTIVE, while i'd actually prefer
> > adding "DVF_FAILED" or something. untested morning-coffee-qual.diff below.
> >
> > comments?
> >
> > -Artturi
> >
> >
> > diff --git sys/dev/gpio/gpioow.c sys/dev/gpio/gpioow.c
> > index 64d79ab0cb8..912537b7de7 100644
> > --- sys/dev/gpio/gpioow.c
> > +++ sys/dev/gpio/gpioow.c
> > @@ -101,7 +101,7 @@ gpioow_attach(struct device *parent, struct device
> > *self, void *aux)
> > /* Check that we have enough pins */
> > if (gpio_npins(ga->ga_mask) != GPIOOW_NPINS) {
> > printf(": invalid pin mask\n");
> > - return;
> > + goto fail_nomap;
> > }
> >
> > /* Map pins */
> > @@ -110,7 +110,7 @@ gpioow_attach(struct device *parent, struct device
> > *self, void *aux)
> > if (gpio_pin_map(sc->sc_gpio, ga->ga_offset, ga->ga_mask,
> > &sc->sc_map)) {
> > printf(": can't map pins\n");
> > - return;
> > + goto fail_nomap;
> > }
> >
> > /* Configure data pin */
> > @@ -153,6 +153,8 @@ gpioow_attach(struct device *parent, struct device
> > *self, void *aux)
> >
> > fail:
> > gpio_pin_unmap(sc->sc_gpio, &sc->sc_map);
> > +fail_nomap:
> > + config_defer_failure(self);
> > }
> >
> > int
> > diff --git sys/kern/subr_autoconf.c sys/kern/subr_autoconf.c
> > index 3fff153e8ad..9a797712510 100644
> > --- sys/kern/subr_autoconf.c
> > +++ sys/kern/subr_autoconf.c
> > @@ -409,6 +409,11 @@ config_attach(struct device *parent, void *match, void
> > *aux, cfprint_t print)
> > if (--autoconf_attdet == 0)
> > wakeup(&autoconf_attdet);
> > mtx_leave(&autoconf_attdet_mtx);
> > +
> > + if ((dev->dv_flags & DVF_ACTIVE) == 0) {
> > + if (config_detach(dev, 0) == 0)
> > + dev = NULL;
> > + }
> > return (dev);
> > }
> >
> > @@ -678,6 +683,17 @@ config_defer(struct device *dev, void (*func)(struct
> > device *))
> > config_pending_incr();
> > }
> >
> > +/*
> > + * Defer the detachment of the specified device until the end
> > + * of its own configuration.
> > + */
> > +void
> > +config_defer_failure(struct device *dev)
> > +{
> > +
> > + dev->dv_flags &= ~DVF_ACTIVE;
> > +}
> > +
> > /*
> > * Defer the configuration of the specified device until after
> > * root file system is mounted.
> > diff --git sys/sys/device.h sys/sys/device.h
> > index 00a1f6ad2a6..3820cc6e0f5 100644
> > --- sys/sys/device.h
> > +++ sys/sys/device.h
> > @@ -185,6 +185,7 @@ int config_activate_children(struct device *, int);
> > struct device *config_make_softc(struct device *parent,
> > struct cfdata *cf);
> > void config_defer(struct device *, void (*)(struct device *));
> > +void config_defer_failure(struct device *);
> > void config_pending_incr(void);
> > void config_pending_decr(void);
> > void config_mountroot(struct device *, void (*)(struct device *));
> >
