[Xen-devel] [PATCH] fix xenconsoled race

[John Levon <levon@xxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User max.zhen@xxxxxxx
# 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@xxxxxxx>

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;
 }
 

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