Messages in this thread | | | Date | Thu, 27 Sep 2012 07:47:46 +0800 | Subject | Re: [BUG] Deferred probing in driver model is racy, resulting in lost probes | From | Ming Lei <> |
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On Thu, Sep 27, 2012 at 4:23 AM, Russell King - ARM Linux <linux@arm.linux.org.uk> wrote: > On Wed, Sep 26, 2012 at 01:08:33PM -0700, Greg Kroah-Hartman wrote: >> On Sun, Sep 16, 2012 at 09:24:43PM +0800, Ming Lei wrote: >> > diff --git a/drivers/base/bus.c b/drivers/base/bus.c >> > index 181ed26..17d7437 100644 >> > --- a/drivers/base/bus.c >> > +++ b/drivers/base/bus.c >> > @@ -714,12 +714,12 @@ int bus_add_driver(struct device_driver *drv) >> > if (error) >> > goto out_unregister; >> > >> > + klist_add_tail(&priv->knode_bus, &bus->p->klist_drivers); >> > if (drv->bus->p->drivers_autoprobe) { >> > error = driver_attach(drv); >> > if (error) >> > goto out_unregister; >> > } >> > - klist_add_tail(&priv->knode_bus, &bus->p->klist_drivers); >> > module_add_driver(drv->owner, drv); >> > >> > error = driver_create_file(drv, &driver_attr_uevent); >> > >> > >> > >> >> Did the above patch ever prove to solve the issue or not? > > To be honest, I've not bothered to test the above patch, and now when I > look at it, I notice it's broken - in that on error it will corrupt the > driver list. Take a look at the error path. > > priv is drv->p. We add priv->knode_bus to the driver list. If > driver_attach() returns an error, then we go to out_unregister, which
In fact, driver_attach() always returns zero, so it does __not__ affect your test.
I knew the failure shouldn't be handled in theory because the probe failure on one device should not cause failure of driver_register, and it should be fixed, IMO.
> does: > > out_unregister: > kobject_put(&priv->kobj); > kfree(drv->p); > drv->p = NULL; > > thereby freeing the node we just added to the driver list without first > removing it. > > I suspect it will fix the problem, but let's get the patch to be correct > before it gets tested...
Trust me, please go ahead to test and it doesn't affect it...
Thanks, -- Ming Lei
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