From: Bjorn Helgaas <helgaas@kernel.org>
To: Niklas Schnelle <schnelle@linux.ibm.com>
Cc: linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-s390@vger.kernel.org, Pierre Morel <pmorel@linux.ibm.com>,
Peter Oberparleiter <oberpar@linux.ibm.com>,
Viktor Mihajlovski <mihajlov@linux.ibm.com>
Subject: Re: [RFC 1/1] s390/pci: expose UID checking state in sysfs
Date: Wed, 13 Jan 2021 12:55:00 -0600 [thread overview]
Message-ID: <20210113185500.GA1918216@bjorn-Precision-5520> (raw)
In-Reply-To: <4f5013a1-3dde-1633-a0cc-591fc439e29d@linux.ibm.com>
On Wed, Jan 13, 2021 at 08:47:58AM +0100, Niklas Schnelle wrote:
> On 1/12/21 10:50 PM, Bjorn Helgaas wrote:
> > On Mon, Jan 11, 2021 at 10:38:57AM +0100, Niklas Schnelle wrote:
> >> We use the UID of a zPCI adapter, or the UID of the function zero if
> >> there are multiple functions in an adapter, as PCI domain if and only if
> >> UID Checking is turned on.
> >> Otherwise we automatically generate domains as devices appear.
> >>
> >> The state of UID Checking is thus essential to know if the PCI domain
> >> will be stable, yet currently there is no way to access this information
> >> from userspace.
> >> So let's solve this by showing the state of UID checking as a sysfs
> >> attribute in /sys/bus/pci/uid_checking
> >> +/* Global zPCI attributes */
> >> +static ssize_t uid_checking_show(struct kobject *kobj,
> >> + struct kobj_attribute *attr, char *buf)
> >> +{
> >> + return sprintf(buf, "%i\n", zpci_unique_uid);
> >> +}
> >> +
> >> +static struct kobj_attribute sys_zpci_uid_checking_attr =
> >> + __ATTR(uid_checking, 0444, uid_checking_show, NULL);
> >
> > Use DEVICE_ATTR_RO instead of __ATTR.
>
> It's my understanding that DEVICE_ATTR_* is only for
> per device attributes. This one is global for the entire
> Z PCI. I just tried with BUS_ATTR_RO instead
> and that works but only if I put the attribute at
> /sys/bus/pci/uid_checking instead of with a zpci
> subfolder. This path would work for us too, we
> currently don't have any other global attributes
> that we are planning to expose but those could of
> course come up in the future.
Ah, I missed the fact that this is a kobj_attribute, not a
device_attribute. Maybe KERNEL_ATTR_RO()? Very few uses so far, but
seems like it might fit?
Bjorn
next prev parent reply other threads:[~2021-01-13 18:56 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-11 9:38 [RFC 0/1] PCI: s390 global attribute "UID Checking" Niklas Schnelle
2021-01-11 9:38 ` [RFC 1/1] s390/pci: expose UID checking state in sysfs Niklas Schnelle
2021-01-12 21:50 ` Bjorn Helgaas
2021-01-13 7:47 ` Niklas Schnelle
2021-01-13 18:55 ` Bjorn Helgaas [this message]
2021-01-14 13:20 ` Niklas Schnelle
2021-01-14 13:44 ` Christian Brauner
2021-01-14 13:58 ` Greg Kroah-Hartman
2021-01-14 15:06 ` Niklas Schnelle
2021-01-14 15:17 ` Greg Kroah-Hartman
2021-01-14 15:51 ` Niklas Schnelle
2021-01-14 16:14 ` Greg Kroah-Hartman
2021-01-15 11:20 ` Niklas Schnelle
2021-01-15 12:02 ` Greg Kroah-Hartman
2021-01-15 15:29 ` Bjorn Helgaas
2021-01-15 16:15 ` Niklas Schnelle
2021-01-21 15:31 ` Niklas Schnelle
2021-01-21 15:54 ` Bjorn Helgaas
2021-01-21 16:11 ` Greg Kroah-Hartman
2021-01-21 17:04 ` Niklas Schnelle
2021-01-21 17:28 ` Greg Kroah-Hartman
2021-01-21 17:43 ` Niklas Schnelle
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