Use inline func to fix deadlock

pkg/scheduler/core/generic_scheduler.go

@@ -430,10 +430,6 @@ func podFitsOnNode(
 	var (
 		eCacheAvailable  bool
 		failedPredicates []algorithm.PredicateFailureReason
-		invalid          bool
-		fit              bool
-		reasons          []algorithm.PredicateFailureReason
-		err              error
 	)
 	predicateResults := make(map[string]HostPredicate)
 
@@ -469,24 +465,37 @@ func podFitsOnNode(
 		// when pods are nominated or their nominations change.
 		eCacheAvailable = equivCacheInfo != nil && !podsAdded
 		for _, predicateKey := range predicates.Ordering() {
+			var (
+				fit     bool
+				reasons []algorithm.PredicateFailureReason
+				err     error
+			)
 			//TODO (yastij) : compute average predicate restrictiveness to export it as Prometheus metric
 			if predicate, exist := predicateFuncs[predicateKey]; exist {
+				// Use an in-line function to guarantee invocation of ecache.Unlock()
+				// when the in-line function returns.
+				func() {
+					var invalid bool
 					if eCacheAvailable {
 						// Lock ecache here to avoid a race condition against cache invalidation invoked
-					// in event handlers. This race has existed despite locks in eCache implementation.
+						// in event handlers. This race has existed despite locks in equivClassCacheimplementation.
 						ecache.Lock()
+						defer ecache.Unlock()
 						// PredicateWithECache will return its cached predicate results.
-					fit, reasons, invalid = ecache.PredicateWithECache(pod.GetName(), info.Node().GetName(), predicateKey, equivCacheInfo.hash, false)
+						fit, reasons, invalid = ecache.PredicateWithECache(
+							pod.GetName(), info.Node().GetName(),
+							predicateKey, equivCacheInfo.hash, false)
 					}
 
 					if !eCacheAvailable || invalid {
 						// we need to execute predicate functions since equivalence cache does not work
 						fit, reasons, err = predicate(pod, metaToUse, nodeInfoToUse)
 						if err != nil {
-						return false, []algorithm.PredicateFailureReason{}, err
+							return
 						}
+
 						if eCacheAvailable {
-						// Store data to update eCache after this loop.
+							// Store data to update equivClassCacheafter this loop.
 							if res, exists := predicateResults[predicateKey]; exists {
 								res.Fit = res.Fit && fit
 								res.FailReasons = append(res.FailReasons, reasons...)
@@ -495,12 +504,15 @@ func podFitsOnNode(
 								predicateResults[predicateKey] = HostPredicate{Fit: fit, FailReasons: reasons}
 							}
 							result := predicateResults[predicateKey]
-						ecache.UpdateCachedPredicateItem(pod.GetName(), info.Node().GetName(), predicateKey, result.Fit, result.FailReasons, equivCacheInfo.hash, false)
+							ecache.UpdateCachedPredicateItem(
+								pod.GetName(), info.Node().GetName(),
+								predicateKey, result.Fit, result.FailReasons, equivCacheInfo.hash, false)
 						}
 					}
+				}()
 
-				if eCacheAvailable {
+				if err != nil {
-					ecache.Unlock()
+					return false, []algorithm.PredicateFailureReason{}, err
 				}
 
 				if !fit {
@@ -508,7 +520,9 @@ func podFitsOnNode(
 					failedPredicates = append(failedPredicates, reasons...)
 					// if alwaysCheckAllPredicates is false, short circuit all predicates when one predicate fails.
 					if !alwaysCheckAllPredicates {
-						glog.V(5).Infoln("since alwaysCheckAllPredicates has not been set, the predicate evaluation is short circuited and there are chances of other predicates failing as well.")
+						glog.V(5).Infoln("since alwaysCheckAllPredicates has not been set, the predicate" +
+							"evaluation is short circuited and there are chances" +
+							"of other predicates failing as well.")
 						break
 					}
 				}