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Description of problem:
If a mediated device is created during libvirtd run, there's a chance the device won't be listed by the following command:
#virsh nodedev-list --cap mdev
Version-Release number of selected component (if applicable):
libvirt-3.2.0-9.virtcov.el7.x86_64
How reproducible:
depending on the environment (on some env 100%, 0% on others)
Steps to Reproduce:
1. start libvirtd
2. create a mediated device
# echo `uuidgen` > \ /sys/class/mdev_bus/<pci_address>/mdev_supported_types/nvidia-X/create
3. virsh nodedev-list --cap mdev returns an empty list
Actual results:
The device won't show up in the output list until the daemon is restarted.
Expected results:
The device shows up in the output list
Additional info:
This is apparently due to a kernel uevent race, where the 'add' uevent is sent prior to creating the whole sysfs device tree, thus at the time of processing the device, some of the requested sysfs attributes might not be exposed yet.
Until this is fixed in the upstream kernel, libvirt needs a workaround fix.
Workaround pushed upstream:
commit 1af45804088c5b1f19fca8631821ba5ae94cf3dd
Author: Erik Skultety <eskultet>
AuthorDate: Tue Jun 20 16:15:22 2017 +0200
Commit: Erik Skultety <eskultet>
CommitDate: Thu Oct 19 08:54:53 2017 +0200
nodedev: udev: Hook up virFileWaitForAccess to work around uevent race
If we find ourselves in the situation that the 'add' uevent has been
fired earlier than the sysfs tree for a device was created, we should
use the best-effort approach and give kernel some predetermined amount
of time, thus waiting for the attributes to be ready rather than
discarding the device from our device list forever. If those don't appear
in the given time frame, we need to move on, since libvirt can't wait
indefinitely.
Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1463285
Signed-off-by: Erik Skultety <eskultet>
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.
For information on the advisory, and where to find the updated
files, follow the link below.
If the solution does not work for you, open a new bug report.
https://access.redhat.com/errata/RHEA-2018:0704