From 7500c8cc7288bcd6f32b7fe27ff094b82d5ba528 Mon Sep 17 00:00:00 2001
From: Alexander Morozov <lk4d4@docker.com>
Date: Tue, 29 Mar 2016 09:43:12 -0700
Subject: [PATCH] libcontainerd: reuse our pkg/locker

it fixes race with access to containerMutexes

Signed-off-by: Alexander Morozov <lk4d4@docker.com>
(cherry picked from commit a7851e2556edb3e5333b6fe53160755fb5b7d616)
---
 libcontainerd/client.go         | 26 +++++++-------------------
 libcontainerd/remote_linux.go   |  7 ++++---
 libcontainerd/remote_windows.go |  8 ++++----
 3 files changed, 15 insertions(+), 26 deletions(-)

diff --git a/libcontainerd/client.go b/libcontainerd/client.go
index 4485b75cf9..7e8e47bcfa 100644
--- a/libcontainerd/client.go
+++ b/libcontainerd/client.go
@@ -4,35 +4,23 @@ import (
 	"fmt"
 	"sync"
 
-	"github.com/Sirupsen/logrus"
+	"github.com/docker/docker/pkg/locker"
 )
 
 // clientCommon contains the platform agnostic fields used in the client structure
 type clientCommon struct {
-	backend          Backend
-	containers       map[string]*container
-	containerMutexes map[string]*sync.Mutex // lock by container ID
-	mapMutex         sync.RWMutex           // protects read/write oprations from containers map
-	sync.Mutex                              // lock for containerMutexes map access
+	backend    Backend
+	containers map[string]*container
+	locker     *locker.Locker
+	mapMutex   sync.RWMutex // protects read/write oprations from containers map
 }
 
 func (clnt *client) lock(containerID string) {
-	clnt.Lock()
-	if _, ok := clnt.containerMutexes[containerID]; !ok {
-		clnt.containerMutexes[containerID] = &sync.Mutex{}
-	}
-	clnt.Unlock()
-	clnt.containerMutexes[containerID].Lock()
+	clnt.locker.Lock(containerID)
 }
 
 func (clnt *client) unlock(containerID string) {
-	clnt.Lock()
-	if l, ok := clnt.containerMutexes[containerID]; ok {
-		l.Unlock()
-	} else {
-		logrus.Warnf("unlock of non-existing mutex: %s", containerID)
-	}
-	clnt.Unlock()
+	clnt.locker.Unlock(containerID)
 }
 
 // must hold a lock for cont.containerID
diff --git a/libcontainerd/remote_linux.go b/libcontainerd/remote_linux.go
index eddcc7fba3..4df3e1f098 100644
--- a/libcontainerd/remote_linux.go
+++ b/libcontainerd/remote_linux.go
@@ -16,6 +16,7 @@ import (
 
 	"github.com/Sirupsen/logrus"
 	containerd "github.com/docker/containerd/api/grpc/types"
+	"github.com/docker/docker/pkg/locker"
 	sysinfo "github.com/docker/docker/pkg/system"
 	"github.com/docker/docker/utils"
 	"golang.org/x/net/context"
@@ -169,9 +170,9 @@ func (r *remote) Cleanup() {
 func (r *remote) Client(b Backend) (Client, error) {
 	c := &client{
 		clientCommon: clientCommon{
-			backend:          b,
-			containerMutexes: make(map[string]*sync.Mutex),
-			containers:       make(map[string]*container),
+			backend:    b,
+			containers: make(map[string]*container),
+			locker:     locker.New(),
 		},
 		remote:        r,
 		exitNotifiers: make(map[string]*exitNotifier),
diff --git a/libcontainerd/remote_windows.go b/libcontainerd/remote_windows.go
index c313779ee2..ce01f74f25 100644
--- a/libcontainerd/remote_windows.go
+++ b/libcontainerd/remote_windows.go
@@ -1,6 +1,6 @@
 package libcontainerd
 
-import "sync"
+import "github.com/docker/docker/pkg/locker"
 
 type remote struct {
 }
@@ -8,9 +8,9 @@ type remote struct {
 func (r *remote) Client(b Backend) (Client, error) {
 	c := &client{
 		clientCommon: clientCommon{
-			backend:          b,
-			containerMutexes: make(map[string]*sync.Mutex),
-			containers:       make(map[string]*container),
+			backend:    b,
+			containers: make(map[string]*container),
+			locker:     locker.New(),
 		},
 	}
 	return c, nil