[PATCH] powerpc/pseries: remove returning ENODEV when uevent is triggered
Lidong Zhong
lidong.zhong at suse.com
Thu Apr 11 11:43:47 AEST 2024
Hi Michael,
After checking the definition of modalias in modalias_show(), I think it's
better to keep the
same logic in vio_hotplug(), that's removing the else part in my original
patch shown below.
+ if (dn && (cp = of_get_property(dn, "compatible", NULL))
+ add_uevent_var(env, "MODALIAS=vio:T%sS%s", vio_dev->type,
cp);
+ else
+ add_uevent_var(env, "MODALIAS=vio:T%s", vio_dev->type);
I think we can avoid some possible regression then. I'll make the change in
my v2 patch.
--
Regards,
Lidong Zhong
On Wed, Apr 10, 2024 at 9:25 AM Lidong Zhong <lidong.zhong at suse.com> wrote:
> Hi Michael,
>
> Thanks for your reply.
>
> On Tue, Apr 9, 2024 at 4:46 PM Michael Ellerman <mpe at ellerman.id.au>
> wrote:
>
>> 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 at 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.
>>
>
> It's an issue reported by our customer. I am sorry I can't provide more
> information because I don't have the environment
> to reproduce this issue. The only related log I got is shown below:
>
> Feb 07 14:08:03 rb3i0060 udevadm[623]: vio: Failed to write 'add' to
> '/sys/devices/vio/uevent', ignoring: No such device
>
> Feb 07 14:08:03 rb3i0060 kernel: synth uevent: /devices/vio: failed to
> send uevent
>
> Feb 07 14:08:03 rb3i0060 kernel: vio vio: uevent: failed to send synthetic
> uevent
>
> Feb 07 14:08:03 rb3i0060 kernel: synth uevent: /devices/vio/4000: failed
> to send uevent
>
> Feb 07 14:08:03 rb3i0060 kernel: vio 4000: uevent: failed to send
> synthetic uevent
>
> Feb 07 14:08:03 rb3i0060 kernel: synth uevent: /devices/vio/4001: failed
> to send uevent
>
> Feb 07 14:08:03 rb3i0060 kernel: vio 4001: uevent: failed to send
> synthetic uevent
>
> Feb 07 14:08:03 rb3i0060 kernel: synth uevent: /devices/vio/4002: failed
> to send uevent
>
> Feb 07 14:08:03 rb3i0060 kernel: vio 4002: uevent: failed to send
> synthetic uevent
>
> Feb 07 14:08:03 rb3i0060 kernel: synth uevent: /devices/vio/4004: failed
> to send uevent
>
> Feb 07 14:08:03 rb3i0060 kernel: vio 4004: uevent: failed to send
> synthetic uevent
>
> Feb 07 14:08:03 rb3i0060 udevadm[623]: 4000: Failed to write 'add' to
> '/sys/devices/vio/4000/uevent', ignoring: No such device
>
> Feb 07 14:08:03 rb3i0060 udevadm[623]: 4001: Failed to write 'add' to
> '/sys/devices/vio/4001/uevent', ignoring: No such device
>
> Feb 07 14:08:03 rb3i0060 udevadm[623]: 4002: Failed to write 'add' to
> '/sys/devices/vio/4002/uevent', ignoring: No such device
>
> Feb 07 14:08:03 rb3i0060 udevadm[623]: 4004: Failed to write 'add' to
> '/sys/devices/vio/4004/uevent', ignoring: No such device
>
> systemd-udev-trigger service calls 'udevadm trigger --type=devices
> --action=add' and kernel returns -ENODEV because either
> dev->of_node is NULL or 'compatible' property is not present. Similar
> cases were already reported after some search, for example
> https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1827162
> https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1845319
> I don't think it causes real problems but confusion to users.
>
>
>> > 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.
>>
>
> You mean something like this?
> @@ -1592,13 +1592,10 @@ static int vio_hotplug(const struct device *dev,
> struct kobj_uevent_env *env)
> const char *cp;
>
> dn = dev->of_node;
> - if (!dn)
> - return -ENODEV;
> - cp = of_get_property(dn, "compatible", NULL);
> - if (!cp)
> - return -ENODEV;
> -
> - add_uevent_var(env, "MODALIAS=vio:T%sS%s", vio_dev->type, cp);
> + if (dn && (cp = of_get_property(dn, "compatible", NULL))
> + add_uevent_var(env, "MODALIAS=vio:T%sS%s", vio_dev->type,
> cp);
> + else
> + add_uevent_var(env, "MODALIAS=vio:T%s", vio_dev->type);
> return 0;
>
>
>>
>> > + 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
>>
>
> Thanks for the suggestion. I'll send a v2 patch.
>
>
> --
> Regards,
> Lidong Zhong
>
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