On Mon, Aug 26, 2019 at 08:56:39AM +0200, Christoph Hellwig wrote: > On Thu, Aug 22, 2019 at 12:10:23PM -0700, Sagi Grimberg wrote: > >> You are correct that this information can be derived from sysfs, but the > >> main reason why we add these here, is because in udev rule we can't > >> just go ahead and start looking these up and parsing these.. > >> > >> We could send the discovery aen with NVME_CTRL_NAME and have > >> then have systemd run something like: > >> > >> nvme connect-all -d nvme0 --sysfs > >> > >> and have nvme-cli retrieve all this stuff from sysfs? > > > > Actually that may be a problem. > > > > There could be a hypothetical case where after the event was fired > > and before it was handled, the discovery controller went away and > > came back again with a different controller instance, and the old > > instance is now a different discovery controller. > > > > This is why we need this information in the event. And we verify this > > information in sysfs in nvme-cli. > > Well, that must be a usual issue with uevents, right? Don't we usually > have a increasing serial number for that or something?
Yes we do, userspace should use it to order events. Does udev not handle that properly today? thanks, greg k-h