I am learning to write a multi-threaded linked list class implementation with basic functionalities such as push to front or back, pop_back and read. I could come up with below implementation:

But, I am not very sure if I covered it right. Please share some opinions on how to make it perfect. Also, I am targeting C++11, so please throw some pointers/suggestions in that area also. Thanks in Advance!

[Edit:]What I am looking for is answers to below questions:

1. Is this a correct approach for acquiring mutex in push and display, in case of multi-threaded environment.
2. How can I prioritize the read/delete/write operations. For example, suppose 1 thread is displaying the data and another thread comes which wants to pop_back from the data. How do I make the changes so that my 2nd thread gets the priority while 1st thread was using my node.
3. I have not much worked in C++11, I just started it few months ago, so I would like to know what more should I be having in my class.
4. In case there are any possible bugs in this code, please let that know too.

I am learning to write a multi-threaded linked list class implementation with basic functionality such as push to front or back, pop_back and read. I came up with this implementation:

But, I am not very sure if I covered it right. Please share some opinions on how to make it perfect. Also, I am targeting C++11, so please throw some pointers/suggestions in that area also.

In particular, I am looking for is answers to these questions:

1. Is this a correct approach for acquiring mutex in push() and display(), in a multi-threaded environment?
2. (削除) How can I prioritize the read/delete/write operations. For example, suppose 1 thread is displaying the data and another thread comes which wants to pop_back from the data. How do I make the changes so that my 2nd thread gets the priority while 1st thread was using my node. (削除ここまで)
3. I have not much worked with C++11 — I just started it few months ago — so I would like to know what more I should have in my class.
4. In case there are any possible bugs in this code, please let me know that too.

I am learning to write a multi-threaded linked list class implementation. I could come up with below implementation:

#include <iostream>
#include <thread>
#include <mutex>
std::mutex m;
template<class T>
class Node{
 public:
 T data;
 Node* next;
 Node(T data):data(data),next(NULL){}
};
template<class T>
class List{
 Node<T> *head;
 public:
 List():head(NULL){}
 List(const List<T>&)=default; //default copy constructor
 List& operator =(const List<T>&)=default; //default assignment
 List(List<T>&&)=default; //default move constructor
 List& operator =(List<T>&&)=default; //default move assignment
 void push_front(T val){
 std::lock_guard<std::mutex> lock(m);
 Node<T>* temp=new Node<T>(val);
 if(head==NULL)
 head=temp;
 else{
 temp->next=head;
 head=temp;
 }
 }
 void pop_back(){
 std::lock_guard<std::mutex> lock(m);
 Node<T>* cur=head;
 while(cur->next->next)
 cur = cur->next;
 Node<T>* temp=cur->next;
 delete(temp);
 cur->next=NULL;
 }
 T front(){
 if(head!=NULL)
 return head->data;
 return -1;
 }
 void push_back(T val){
 std::lock_guard<std::mutex> lock(m);
 Node<T>* temp=new Node<T>(val);
 if(head==NULL)
 head=temp;
 else{
 Node<T>* cur=head;
 while(cur->next)
 cur = cur->next;
 cur->next=temp;
 }
 }
 int size(){
 int size=0;
 Node<T>* cur=head;
 while(cur){
 size++;
 cur=cur->next;
 }
 return size;
 }
 void display(){
 std::lock_guard<std::mutex> lock(m);
 Node<T>* cur=head;
 while(cur){
 std::cout<<cur->data<<" ";
 cur = cur->next;
 }
 std::cout<<"\n";
 }
 ~List(){
 Node<T>* current = head;
 Node<T>* next;
 while (current != NULL) {
 next = current->next;
 delete current;
 current = next;
 }
 }
};

I am learning to write a multi-threaded linked list class implementation with basic functionalities such as push to front or back, pop_back and read. I could come up with below implementation:

#include <iostream>
#include <thread>
#include <mutex>
std::mutex m;
template<class T>
class Node{
 public:
 T data;
 Node* next;
 Node(T data):data(data),next(NULL){}
};
template<class T>
class List{
 Node<T> *head;
 public:
 List():head(NULL){}
 List(const List<T>&)=default; //default copy constructor
 List& operator =(const List<T>&)=default; //default assignment
 List(List<T>&&)=default; //default move constructor
 List& operator =(List<T>&&)=default; //default move assignment
 void push_front(T val){ //push data to front
 std::lock_guard<std::mutex> lock(m);
 Node<T>* temp=new Node<T>(val);
 if(head==NULL)
 head=temp;
 else{
 temp->next=head;
 head=temp;
 }
 }
 void pop_back(){ //pop from back
 std::lock_guard<std::mutex> lock(m);
 Node<T>* cur=head;
 while(cur->next->next)
 cur = cur->next;
 Node<T>* temp=cur->next;
 delete(temp);
 cur->next=NULL;
 }
 T front(){ //return front of Linkedlist
 if(head!=NULL)
 return head->data;
 return -1;
 }
 void push_back(T val){ //push at back
 std::lock_guard<std::mutex> lock(m);
 Node<T>* temp=new Node<T>(val);
 if(head==NULL)
 head=temp;
 else{
 Node<T>* cur=head;
 while(cur->next)
 cur = cur->next;
 cur->next=temp;
 }
 }
 int size(){ //return size
 int size=0;
 Node<T>* cur=head;
 while(cur){
 size++;
 cur=cur->next;
 }
 return size;
 }
 void display(){ //read from linked list
 std::lock_guard<std::mutex> lock(m);
 Node<T>* cur=head;
 while(cur){
 std::cout<<cur->data<<" ";
 cur = cur->next;
 }
 std::cout<<"\n";
 }
 ~List(){
 Node<T>* current = head;
 Node<T>* next;
 while (current != NULL) {
 next = current->next;
 delete current;
 current = next;
 }
 }
};

[Edit:]What I am looking for is answers to below questions:

1. Is this a correct approach for acquiring mutex in push and display, in case of multi-threaded environment.
2. How can I prioritize the read/delete/write operations. For example, suppose 1 thread is displaying the data and another thread comes which wants to pop_back from the data. How do I make the changes so that my 2nd thread gets the priority while 1st thread was using my node.
3. I have not much worked in C++11, I just started it few months ago, so I would like to know what more should I be having in my class.
4. In case there are any possible bugs in this code, please let that know too.