On Mon, May 10, 2021 at 09:42:46AM +0200, Niklas Schnelle wrote: > On Fri, 2021-05-07 at 23:25 -0400, Sasha Levin wrote: > > This is a note to let you know that I've just added the patch titled > > > > s390/pci: expose UID uniqueness guarantee > > > > to the 5.12-stable tree which can be found at: > > http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary > > > > The filename of the patch is: > > s390-pci-expose-uid-uniqueness-guarantee.patch > > and it can be found in the queue-5.12 subdirectory. > > > > If you, or anyone else, feels it should not be added to the stable tree, > > please let <stable@xxxxxxxxxxxxxxx> know about it. > > > > > > > > commit 7b9825aa0891087c5c91be0fb75431919e2027e3 > > Author: Niklas Schnelle <schnelle@xxxxxxxxxxxxx> > > Date: Wed Feb 24 11:29:36 2021 +0100 > > > > s390/pci: expose UID uniqueness guarantee > > > > [ Upstream commit 408f2c9c15682fc21b645fdec1f726492e235c4b ] > > > > On s390 each PCI device has a user-defined ID (UID) exposed under > > /sys/bus/pci/devices/<dev>/uid. This ID was designed to serve as the PCI > > device's primary index and to match the device within Linux to the > > device configured in the hypervisor. To serve as a primary identifier > > the UID must be unique within the Linux instance, this is guaranteed by > > the platform if and only if the UID Uniqueness Checking flag is set > > within the CLP List PCI Functions response. > > > > While the UID has been exposed to userspace since commit ac4995b9d570 > > ("s390/pci: add some new arch specific pci attributes") whether or not > > the platform guarantees its uniqueness for the lifetime of the Linux > > instance while defined is not visible from userspace. Remedy this by > > exposing this as a per device attribute at > > > > /sys/bus/pci/devices/<dev>/uid_is_unique > > > > Keeping this a per device attribute allows for maximum flexibility if we > > ever end up with some devices not having a UID or not enjoying the > > guaranteed uniqueness. > > > > Signed-off-by: Niklas Schnelle <schnelle@xxxxxxxxxxxxx> > > Reviewed-by: Viktor Mihajlovski <mihajlov@xxxxxxxxxxxxx> > > Signed-off-by: Heiko Carstens <hca@xxxxxxxxxxxxx> > > Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> > > > > > > Hi Sasha, > > I think we should not backport this patch to the stable kernels either > 5.12, 5.11 nor 5.10. > > The reason is that I'd like this staty together with commit > 81bbf03905aa ("s390/pci: expose a PCI device's UID as its index") since > this then allows to reason that if uid_is_unique is 1 that implies that > the index attribute must exist. On the other hand backporting the other > patch too would create new network interface names. I reckon that > there would be some value for the uid_is_unique attribute alone but I > think it's not worth having more possible scenarios. Good point, now dropped from everywhere, thanks. greg k-h
