From b1818e4a5ff5b37050cbc4d83c9597683142a93c Mon Sep 17 00:00:00 2001
From: networkop <mmkashin@gmail.com>
Date: Fri, 16 Jul 2021 10:45:58 +0100
Subject: [PATCH] fixing a case with no serialWorkers

---
 clab/clab.go | 22 ++++++++++++----------
 1 file changed, 12 insertions(+), 10 deletions(-)

diff --git a/clab/clab.go b/clab/clab.go
index 81d019256..0e9548658 100644
--- a/clab/clab.go
+++ b/clab/clab.go
@@ -171,10 +171,6 @@ func (c *CLab) GlobalRuntime() runtime.ContainerRuntime {
 func (c *CLab) CreateNodes(ctx context.Context, maxWorkers uint, serialNodes map[string]struct{}) {
 
 	wg := new(sync.WaitGroup)
-	wg.Add(int(maxWorkers))
-	if len(serialNodes) > 0 {
-		wg.Add(1)
-	}
 
 	concurrentChan := make(chan nodes.Node)
 	serialChan := make(chan nodes.Node)
@@ -208,12 +204,18 @@ func (c *CLab) CreateNodes(ctx context.Context, maxWorkers uint, serialNodes map
 	}
 
 	// start concurrent workers
+	wg.Add(int(maxWorkers))
+	// it's safe to not check if all nodes are serial because in that case
+	// maxWorkers will be 0
 	for i := uint(0); i < maxWorkers; i++ {
 		go workerFunc(i, concurrentChan, wg)
 	}
 
 	// start the serial worker
-	go workerFunc(maxWorkers, serialChan, wg)
+	if len(serialNodes) > 0 {
+		wg.Add(1)
+		go workerFunc(maxWorkers, serialChan, wg)
+	}
 
 	// send nodes to workers
 	for _, n := range c.Nodes {
@@ -289,10 +291,6 @@ func (c *CLab) CreateLinks(ctx context.Context, workers uint, postdeploy bool) {
 func (c *CLab) DeleteNodes(ctx context.Context, workers uint, deleteCandidates map[string]nodes.Node, serialNodes map[string]struct{}) {
 
 	wg := new(sync.WaitGroup)
-	wg.Add(int(workers))
-	if len(serialNodes) > 0 {
-		wg.Add(1)
-	}
 
 	concurrentChan := make(chan nodes.Node)
 	serialChan := make(chan nodes.Node)
@@ -317,12 +315,16 @@ func (c *CLab) DeleteNodes(ctx context.Context, workers uint, deleteCandidates m
 	}
 
 	// start concurrent workers
+	wg.Add(int(workers))
 	for i := uint(0); i < workers; i++ {
 		go workerFunc(i, concurrentChan, wg)
 	}
 
 	// start the serial worker
-	go workerFunc(workers, serialChan, wg)
+	if len(serialNodes) > 0 {
+		wg.Add(1)
+		go workerFunc(workers, serialChan, wg)
+	}
 
 	// send nodes to workers
 	for _, n := range c.Nodes {