[PATCH] fix race condition between xenconsoled and the removal of the entry of a dying domU from xenstore

[Max Zhen <Max.Zhen@Sun.COM>]

# HG changeset patch
# User cz147101@xenbld.sfbay.sun.com
# Node ID db465ecb164e6d89290ae3d4fcc029e29305ae7d
# Parent c682ae7a17224dc5576ba3c5db47766b2a7dc159
Shouldn't call domain_create_ring() for a domU which is shutting down.
There is a race condition between domain_create_ring() and the removal
of the do
mU entry from xenstore. If the removal of the domU entry from xenstore
comes lat
er than the first xs_gather() call in domain_create_ring(), it will go
on and bi
nd the evtchn port to the dying domU, which will cause below error message:
(XEN) (file=event_channel.c, line=144) EVTCHNOP failure: domain 0, error
-22, li
ne 144

Signed-off-by: Max Zhen <max.zhen@sun.com>

diff -r c682ae7a1722 -r db465ecb164e tools/console/daemon/io.c
--- a/tools/console/daemon/io.c Fri Sep 01 12:16:21 2006 +0100
+++ b/tools/console/daemon/io.c Fri Sep 01 08:14:07 2006 -0700
@@ -293,12 +293,14 @@ static bool watch_domain(struct domain *
bool success;

sprintf(domid_str, "dom%u", dom->domid);
- if (watch)
+ if (watch) {
success = xs_watch(xs, dom->conspath, domid_str);
- else
+ if (success)
+ domain_create_ring(dom);
+ } else {
success = xs_unwatch(xs, dom->conspath, domid_str);
- if (success)
- domain_create_ring(dom);
+ }
+
return success;
}