Re: [PATCH] powerpc/pseries: remove returning ENODEV when uevent is triggered

[Michael Ellerman <mpe@ellerman.id.au>]

Hi Lidong,

Thanks for the patch.

I'm not an expert on udev etc. so apologies if any of these questions
are stupid.

Lidong Zhong <lidong.zhong@suse.com> writes:
> We have noticed the following nuisance messages during boot
>
> [    7.120610][ T1060] vio vio: uevent: failed to send synthetic uevent
> [    7.122281][ T1060] vio 4000: uevent: failed to send synthetic uevent
> [    7.122304][ T1060] vio 4001: uevent: failed to send synthetic uevent
> [    7.122324][ T1060] vio 4002: uevent: failed to send synthetic uevent
> [    7.122345][ T1060] vio 4004: uevent: failed to send synthetic uevent
>
> It's caused by either vio_register_device_node() failed to set dev->of_node or
> the missing "compatible" property. Try return as much information as possible
> instead of a failure.

Does udev etc. cope with that? Can we just change the content of the
MODALIAS value like that?

With this patch we'll start emitting uevents for devices we previously
didn't. I guess that's OK because nothing is expecting them?

Can you include a log of udev showing the event firing and that nothing
breaks.

On my system here I see nothing matches the devices except for libvpd,
which seems to match lots of things.

> diff --git a/arch/powerpc/platforms/pseries/vio.c b/arch/powerpc/platforms/pseries/vio.c
> index 90ff85c879bf..62961715ca24 100644
> --- a/arch/powerpc/platforms/pseries/vio.c
> +++ b/arch/powerpc/platforms/pseries/vio.c
> @@ -1593,12 +1593,13 @@ static int vio_hotplug(const struct device *dev, struct kobj_uevent_env *env)
>  
>  	dn = dev->of_node;
>  	if (!dn)
> -		return -ENODEV;
> +		goto out;
>  	cp = of_get_property(dn, "compatible", NULL);
>  	if (!cp)
> -		return -ENODEV;
> -
> -	add_uevent_var(env, "MODALIAS=vio:T%sS%s", vio_dev->type, cp);
> +		add_uevent_var(env, "MODALIAS=vio:T%s", vio_dev->type);

If it's OK to skip the compatible property then we don't need the
of_node at all, and we could always emit this, even when of_node is not
available.

> +    else
> +		add_uevent_var(env, "MODALIAS=vio:T%sS%s", vio_dev->type, cp);
> +out:
>  	return 0;
>  }

I think we also should update the vio modalias_show() to follow the same
logic, otherwise the uevent MODALIAS value and the modalias file won't
match which is confusing.

Preferably vio_hotplug() and modalias_show() would just call a common
helper.

cheers