Re: [libvirt] [PATCH 11/17] util: Introduce libvirt_udevhelper

On Thu, Oct 27, 2016 at 8:37 AM, Jiri Denemark <jdenemar(a)redhat.com&gt; wrote: I am working on udev hook-up. I found out that SECLABEL key doesn't support substitutions (see %c in man 7 udev). I need to fix that first and then we can have very simple udev rule file that employs helper. This is my WIP version, # /etc/udev/rules.d/99-virt.rules ACTION!="add|change", GOTO="virt_rules_end" SUBSYSTEM!="block", GOTO="virt_rules_end" PROGRAM="/usr/local/libexec/libvirt_udevhelper", OWNER="%c{1}", GROUP="%c{2}", SECLABEL{selinux}="%c{3}", TAG+="libvirt" LABEL="virt_rules_end" SECLABEL part doesn't work yet. Also helper uses DEVNODE env variable to obtain path to work with. It should use DEVNAME. This is my fault, because I told Michal to use DEVNODE. I've patched it locally for now. I will send PR to Michal with the fix. One more thing I want to work on is to close the possibility of a race when execution of a change event is in-flight and user starts VM. Then libvirtd writes to devices.udev file and launches qemu driver, but execution of prior change event may finish and hence reset permissions to whatever was there before libvirtd wrote to devices.udev database. That is why I am adding TAG to the device. What we could do, is to write devices.udev database and then trigger change event from libvirtd and locally wait for its completion (no need for event-loop integration), that would be indicated by TAG being present in the event environment. However, even w/o this, proposed patch series very much improves current state. Michal