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<p class="MsoNormal">Hi,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span style="font-family:Consolas">I meet a problem that libvirt handle new mediated devices wrongly.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:Consolas">Command `virsh nodedev-list –cap mdev` return none after I create a mdev, and the root cause I found is:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:Consolas"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:Consolas">// kernel code <o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:Consolas">int mdev_device_create(struct kobject *kobj, struct device *dev, uuid_le uuid)<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:Consolas">{<o:p></o:p></span></p>
<p class="MsoNormal" style="text-indent:24.0pt"><span style="font-family:Consolas">...<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:Consolas"> <i>ret = device_register(&mdev->dev); // send udev event here --- 1<o:p></o:p></i></span></p>
<p class="MsoNormal"><span style="font-family:Consolas"> if (ret) {<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:Consolas"> put_device(&mdev->dev);<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:Consolas"> goto create_err;<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:Consolas"> }<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:Consolas"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:Consolas"> ret = mdev_device_create_ops(kobj, mdev);<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:Consolas"> if (ret)<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:Consolas"> goto create_failed;<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:Consolas"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:Consolas"> <i>ret = mdev_create_sysfs_files(&mdev->dev, type); // create mdev_type symbol link here --- 2<o:p></o:p></i></span></p>
<p class="MsoNormal"><span style="font-family:Consolas"> if (ret) {<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:Consolas"> mdev_device_remove_ops(mdev, true);<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:Consolas"> goto create_failed;<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:Consolas"> }<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:Consolas"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:Consolas"> mdev->type_kobj = kobj;<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:Consolas"> dev_dbg(&mdev->dev, "MDEV: created\n");<o:p></o:p></span></p>
<p class="MsoNormal" style="text-indent:24.0pt"><span style="font-family:Consolas">...<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:Consolas">}<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:Consolas"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:Consolas">At point 1, kernel send a udev event(add). If libvirt receive this event and handle it before kernel code reach point 2, libvirt<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:Consolas">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’
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:Consolas">because the link haven’t been created yet. Then libvirt thinks this devices doesn’t exsit and stop tracking info of this device.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:Consolas">Finally, command `vish nodedev-list –cap` return nothing though the device exist at host indeed.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:Consolas"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:Consolas">To make it easy to reproduce this problem, I just add a `udelay(1)` before point 2 by kprobe.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:Consolas"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:Consolas">So I think maybe we should add ‘kobject_uevent(..., KOBJ_ADD)’ after point 2 instead of point 1 ?<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:Consolas">Or is there any other method to solve this problem?<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:Consolas;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:Consolas;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Thanks,<o:p></o:p></p>
<p class="MsoNormal">Zongyong Wu<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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