From 1240690973140938e7d576b2672c8c4dcb0efee2 Mon Sep 17 00:00:00 2001
From: Matthew Holt <mholt@users.noreply.github.com>
Date: Tue, 19 Jul 2016 12:05:40 -0600
Subject: [PATCH] Avoid deadlock (fixes #941)

---
 caddy.go | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/caddy.go b/caddy.go
index 2869ed42..401c6fc6 100644
--- a/caddy.go
+++ b/caddy.go
@@ -696,14 +696,19 @@ func loadServerBlocks(serverType, filename string, input io.Reader) ([]caddyfile
 // instances after stopping is completed. Do not re-use any
 // references to old instances after calling Stop.
 func Stop() error {
-	instancesMu.Lock()
-	for _, inst := range instances {
+	// This awkward for loop is to avoid a deadlock since
+	// inst.Stop() also acquires the instancesMu lock.
+	for {
+		instancesMu.Lock()
+		if len(instances) == 0 {
+			break
+		}
+		inst := instances[0]
+		instancesMu.Unlock()
 		if err := inst.Stop(); err != nil {
 			log.Printf("[ERROR] Stopping %s: %v", inst.serverType, err)
 		}
 	}
-	instances = []*Instance{}
-	instancesMu.Unlock()
 	return nil
 }