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Merge pull request #30872 from mwielgus/fed-informer-deadlock

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Automatic merge from submit-queue

Fix deadlock possibility in federated informer

On cluster add subinformer locks and tries to add cluster to federated informer. When someone checks if everything is in sync federated informer is locked and then subinformer is inspected what apparently requires a lock. With really bad timing this can create a deadlock.

This PR ensures that there is always at most 1 lock taken in federated informer.

cc: @quinton-hoole @kubernetes/sig-cluster-federation 

Fixes: #30855
This commit is contained in:
Kubernetes Submit Queue 2016-08-18 08:31:26 -07:00 committed by GitHub
commit b15c2d67e6
1 changed files with 22 additions and 11 deletions
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33
federation/pkg/federation-controller/util/federated_informer.go
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@ -344,8 +344,6 @@ func (f *federatedInformerImpl) getReadyClusterUnlocked(name string) (*federatio
// Synced returns true if the view is synced (for the first time)
func (f *federatedInformerImpl) ClustersSynced() bool {
f.Lock()
defer f.Unlock()
return f.clusterInformer.controller.HasSynced()
}
@ -452,18 +450,31 @@ func (fs *federatedStoreImpl) GetKeyFor(item interface{}) string {
// Checks whether stores for all clusters form the lists (and only these) are there and
// are synced.
func (fs *federatedStoreImpl) ClustersSynced(clusters []*federation_api.Cluster) bool {
fs.federatedInformer.Lock()
defer fs.federatedInformer.Unlock()
if len(fs.federatedInformer.targetInformers) != len(clusters) {
// Get the list of informers to check under a lock and check it outside.
okSoFar, informersToCheck := func() (bool, []informer) {
fs.federatedInformer.Lock()
defer fs.federatedInformer.Unlock()
if len(fs.federatedInformer.targetInformers) != len(clusters) {
return false, []informer{}
}
informersToCheck := make([]informer, 0, len(clusters))
for _, cluster := range clusters {
if targetInformer, found := fs.federatedInformer.targetInformers[cluster.Name]; found {
informersToCheck = append(informersToCheck, targetInformer)
} else {
return false, []informer{}
}
}
return true, informersToCheck
}()
if !okSoFar {
return false
}
for _, cluster := range clusters {
if targetInformer, found := fs.federatedInformer.targetInformers[cluster.Name]; found {
if !targetInformer.controller.HasSynced() {
return false
}
} else {
for _, informerToCheck := range informersToCheck {
if !informerToCheck.controller.HasSynced() {
return false
}
}