Gary Grebus
2009-Nov-02 21:35 UTC
[Xen-devel] [PATCH 1/2] Fix problems with vbd hotplug on Linux
Avoid races between hotplug "add" and "remove" leading to
"leaked"
loopback devices.
- Don''t setup loopback device if xend is no longer waiting for the vbd.
- Use the lock file to avoid add/remove races.
Signed-off-by: Gary Grebus <gary.grebus@oracle.com>
diff -r 8ca4e32583b6 tools/hotplug/Linux/block
--- a/tools/hotplug/Linux/block Fri Oct 23 10:15:17 2009 +0100
+++ b/tools/hotplug/Linux/block Mon Oct 26 12:34:57 2009 -0400
@@ -233,6 +233,15 @@
claim_lock "block"
+ # Avoid a race with the remove if the path has been deleted, or
+ # otherwise changed from "InitWait" state e.g. due to a timeout
+ xenbus_state=$(xenstore_read_default "$XENBUS_PATH/state"
''unknown'')
+ if [ "$xenbus_state" != ''2'' ]
+ then
+ release_lock "block"
+ fatal "Path closed or removed during hotplug add: $XENBUS_PATH
state: $xenbus_state"
+ fi
+
if [ "$mode" = ''w'' ] && ! stat
"$file" -c %A | grep -q w
then
release_lock "block"
@@ -363,8 +372,10 @@
;;
file)
+ claim_lock "block"
node=$(xenstore_read "$XENBUS_PATH/node")
losetup -d "$node"
+ release_lock "block"
exit 0
;;
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