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qmemman: refresh domain list holding global_lock

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Retrieve a domain list only after obtaining global lock. Otherwise an
outdated list may be used, when a domain was introduced in the meantime
(starting a new domain is done with global lock held), leading to #1389.

QubesOS/qubes-issues#1389
This commit is contained in:
Marek Marczykowski-Górecki 2016-01-14 04:34:53 +01:00
parent caa75cbc18
commit 411e8b5323
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GPG Key ID: 063938BA42CFA724
1 changed files with 17 additions and 19 deletions
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36
qmemman/qmemman_server.py
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@ -73,36 +73,34 @@ class XS_Watcher:
def domain_list_changed(self, param):
self.log.debug('domain_list_changed(param={!r})'.format(param))
curr = self.handle.ls('', '/local/domain')
if curr == None:
return
# check if domain is really there, it may happen that some empty
# directories are left in xenstore
curr = filter(
lambda x:
self.handle.read('',
'/local/domain/{}/domid'.format(x)
) is not None,
curr
)
self.log.debug('curr={!r}'.format(curr))
self.log.debug('acquiring global_lock')
global_lock.acquire()
self.log.debug('global_lock acquired')
try:
curr = self.handle.ls('', '/local/domain')
if curr is None:
return
# check if domain is really there, it may happen that some empty
# directories are left in xenstore
curr = filter(
lambda x:
self.handle.read('',
'/local/domain/{}/domid'.format(x)
) is not None,
curr
)
self.log.debug('curr={!r}'.format(curr))
for i in only_in_first_list(curr, self.watch_token_dict.keys()):
#new domain has been created
# new domain has been created
watch = WatchType(XS_Watcher.meminfo_changed, i)
self.watch_token_dict[i] = watch
self.handle.watch(get_domain_meminfo_key(i), watch)
system_state.add_domain(i)
for i in only_in_first_list(self.watch_token_dict.keys(), curr):
#domain destroyed
# domain destroyed
self.handle.unwatch(get_domain_meminfo_key(i), self.watch_token_dict[i])
self.watch_token_dict.pop(i)
system_state.del_domain(i)