Could you please share what the commit id is ? Thanks, Zongyong Wu > -----Original Message----- > From: Erik Skultety [mailto:eskultet@xxxxxxxxxx] > Sent: Thursday, February 01, 2018 4:09 PM > To: Wuzongyong (Euler Dept) <cordius.wu@xxxxxxxxxx> > Cc: Alex Williamson <alex.williamson@xxxxxxxxxx>; libvir-list@xxxxxxxxxx; > weijinfen <weijinfen@xxxxxxxxxx> > Subject: Re: [Question] nodedev-list --cap return nothing after > creating a mdev > > On Thu, Feb 01, 2018 at 07:19:45AM +0000, Wuzongyong (Euler Dept) wrote: > > Hi, > > > > I meet a problem that libvirt handle new mediated devices wrongly. > > Command `virsh nodedev-list -cap mdev` return none after I create a mdev, > and the root cause I found is: > > > > // kernel code > > int mdev_device_create(struct kobject *kobj, struct device *dev, > > uuid_le uuid) { ... > > ret = device_register(&mdev->dev); // send udev event here --- 1 > > if (ret) { > > put_device(&mdev->dev); > > goto create_err; > > } > > > > ret = mdev_device_create_ops(kobj, mdev); > > if (ret) > > goto create_failed; > > > > ret = mdev_create_sysfs_files(&mdev->dev, type); // create > mdev_type symbol link here --- 2 > > if (ret) { > > mdev_device_remove_ops(mdev, true); > > goto create_failed; > > } > > > > mdev->type_kobj = kobj; > > dev_dbg(&mdev->dev, "MDEV: created\n"); ... > > } > > > > At point 1, kernel send a udev event(add). If libvirt receive this > > event and handle it before kernel code reach point 2, libvirt just fail > to resolve link such as > '/sys/devices/pci0000:80/0000:80:02.0/0000:81:00.0/36b79575-ada8-4406- > 893d-8cfd8d10a984/mdev_type' > > because the link haven't been created yet. Then libvirt thinks this > devices doesn't exsit and stop tracking info of this device. > > Finally, command `vish nodedev-list -cap` return nothing though the > device exist at host indeed. > > > > To make it easy to reproduce this problem, I just add a `udelay(1)` > before point 2 by kprobe. > > > > So I think maybe we should add 'kobject_uevent(..., KOBJ_ADD)' after > point 2 instead of point 1 ? > > Or is there any other method to solve this problem? > > Hi, > just a note, we worked around this in upstream libvirt already. > > Thanks for the pointer though, I'd also be interested in possible > solutions in kernel. > > Erik -- libvir-list mailing list libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list
