Red Hat Bugzilla – Bug 434802
xenkbd can deadlock virtual keyboard on resume
Last modified: 2008-07-21 12:45:39 EDT
Description of problem:
xenkbd_resume() fails to reinitialize the shared page. If the driver resumes
with a full ring buffer, it deadlocks: the frontend won't drain the ring buffer
until notified through the event channel, and the backend won't notify while the
ring buffer is full.
Upstream fix: http://xenbits.xensource.com/linux-2.6.18-xen.hg?rev/90fbf541d772
It should be possible to trigger the bug by moving the mouse in the guest's
virtual screen during save.
You need to reinitialize the device to get it unstuck. Reboot works. Maybe
driver unbind / bind could also work, but when I tried it, the device
reinitialized as /class/input/input2, and X was not happy.
Clarification: rebooting the *guest* works. No need to reboot the host.
Created attachment 295929 [details]
Addresses bug 434800 and bug 434806 as well.
XS upstream fixed bug 434802 in
That fix clears just the defined members of the shared page. My patch clears
the whole shared page, both on probe and resume. Makes more sense, and matches
the framebuffer device's behavior.
This request was evaluated by Red Hat Product Management for inclusion in a Red
Hat Enterprise Linux maintenance release. Product Management has requested
further review of this request by Red Hat Engineering, for potential
inclusion in a Red Hat Enterprise Linux Update release for currently deployed
products. This request is not yet committed for inclusion in an Update
The patch in comment#3 also addresses bug 451807.
The proposed fix has been committed as a fix for bug 434800. Turning this one
into a duplicate of 434800 to keep things simple and sane.
*** This bug has been marked as a duplicate of 434800 ***