diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c
index f277e5fc80565f54a4737e7378ba5e8cc63b894c..2a2b1cc194b63342dbaeeb4263b0b7930632c60b 100644
--- a/net/smc/af_smc.c
+++ b/net/smc/af_smc.c
@@ -128,11 +128,27 @@ struct proto smc_proto6 = {
 };
 EXPORT_SYMBOL_GPL(smc_proto6);
 
+static void smc_fback_restore_callbacks(struct smc_sock *smc)
+{
+	struct sock *clcsk = smc->clcsock->sk;
+
+	write_lock_bh(&clcsk->sk_callback_lock);
+	clcsk->sk_user_data = NULL;
+
+	smc_clcsock_restore_cb(&clcsk->sk_state_change, &smc->clcsk_state_change);
+	smc_clcsock_restore_cb(&clcsk->sk_data_ready, &smc->clcsk_data_ready);
+	smc_clcsock_restore_cb(&clcsk->sk_write_space, &smc->clcsk_write_space);
+	smc_clcsock_restore_cb(&clcsk->sk_error_report, &smc->clcsk_error_report);
+
+	write_unlock_bh(&clcsk->sk_callback_lock);
+}
+
 static void smc_restore_fallback_changes(struct smc_sock *smc)
 {
 	if (smc->clcsock->file) { /* non-accepted sockets have no file yet */
 		smc->clcsock->file->private_data = smc->sk.sk_socket;
 		smc->clcsock->file = NULL;
+		smc_fback_restore_callbacks(smc);
 	}
 }
 
@@ -258,6 +274,7 @@ static struct sock *smc_sock_alloc(struct net *net, struct socket *sock,
 	sk->sk_prot->hash(sk);
 	sk_refcnt_debug_inc(sk);
 	mutex_init(&smc->clcsock_release_lock);
+	smc_init_saved_callbacks(smc);
 
 	return sk;
 }
@@ -523,12 +540,134 @@ static void smc_link_save_peer_info(struct smc_link *link,
 	link->peer_mtu = clc->r0.qp_mtu;
 }
 
-static void smc_switch_to_fallback(struct smc_sock *smc)
+/* must be called under rcu read lock */
+static void smc_fback_wakeup_waitqueue(struct smc_sock *smc, void *key)
+{
+	struct socket_wq *wq;
+	__poll_t flags;
+
+	wq = rcu_dereference(smc->sk.sk_wq);
+	if (!skwq_has_sleeper(wq))
+		return;
+
+	/* wake up smc sk->sk_wq */
+	if (!key) {
+		/* sk_state_change */
+		wake_up_interruptible_all(&wq->wait);
+	} else {
+		flags = key_to_poll(key);
+		if (flags & (EPOLLIN | EPOLLOUT))
+			/* sk_data_ready or sk_write_space */
+			wake_up_interruptible_sync_poll(&wq->wait, flags);
+		else if (flags & EPOLLERR)
+			/* sk_error_report */
+			wake_up_interruptible_poll(&wq->wait, flags);
+	}
+}
+
+static int smc_fback_mark_woken(wait_queue_entry_t *wait,
+				unsigned int mode, int sync, void *key)
+{
+	struct smc_mark_woken *mark =
+			container_of(wait, struct smc_mark_woken, wait_entry);
+
+	mark->woken = true;
+	mark->key = key;
+	return 0;
+}
+
+static void smc_fback_forward_wakeup(struct smc_sock *smc, struct sock *clcsk,
+				     void (*clcsock_callback)(struct sock *sk))
+{
+	struct smc_mark_woken mark = { .woken = false };
+	struct socket_wq *wq;
+
+	init_waitqueue_func_entry(&mark.wait_entry,
+				  smc_fback_mark_woken);
+
+	rcu_read_lock();
+	wq = rcu_dereference(clcsk->sk_wq);
+	if (!wq)
+		goto out;
+	add_wait_queue(sk_sleep(clcsk), &mark.wait_entry);
+	clcsock_callback(clcsk);
+	remove_wait_queue(sk_sleep(clcsk), &mark.wait_entry);
+
+	if (mark.woken)
+		smc_fback_wakeup_waitqueue(smc, mark.key);
+out:
+	rcu_read_unlock();
+}
+
+static void smc_fback_state_change(struct sock *clcsk)
+{
+	struct smc_sock *smc;
+
+	read_lock_bh(&clcsk->sk_callback_lock);
+	smc = smc_clcsock_user_data(clcsk);
+	if (smc)
+		smc_fback_forward_wakeup(smc, clcsk,
+					 smc->clcsk_state_change);
+	read_unlock_bh(&clcsk->sk_callback_lock);
+}
+
+static void smc_fback_data_ready(struct sock *clcsk)
+{
+	struct smc_sock *smc;
+
+	read_lock_bh(&clcsk->sk_callback_lock);
+	smc = smc_clcsock_user_data(clcsk);
+	if (smc)
+		smc_fback_forward_wakeup(smc, clcsk,
+					 smc->clcsk_data_ready);
+	read_unlock_bh(&clcsk->sk_callback_lock);
+}
+
+static void smc_fback_write_space(struct sock *clcsk)
+{
+	struct smc_sock *smc;
+
+	read_lock_bh(&clcsk->sk_callback_lock);
+	smc = smc_clcsock_user_data(clcsk);
+	if (smc)
+		smc_fback_forward_wakeup(smc, clcsk,
+					 smc->clcsk_write_space);
+	read_unlock_bh(&clcsk->sk_callback_lock);
+}
+
+static void smc_fback_error_report(struct sock *clcsk)
 {
-	wait_queue_head_t *smc_wait = sk_sleep(&smc->sk);
-	wait_queue_head_t *clc_wait = sk_sleep(smc->clcsock->sk);
-	unsigned long flags;
+	struct smc_sock *smc;
+
+	read_lock_bh(&clcsk->sk_callback_lock);
+	smc = smc_clcsock_user_data(clcsk);
+	if (smc)
+		smc_fback_forward_wakeup(smc, clcsk,
+					 smc->clcsk_error_report);
+	read_unlock_bh(&clcsk->sk_callback_lock);
+}
 
+static void smc_fback_replace_callbacks(struct smc_sock *smc)
+{
+	struct sock *clcsk = smc->clcsock->sk;
+
+	write_lock_bh(&clcsk->sk_callback_lock);
+	clcsk->sk_user_data = (void *)((uintptr_t)smc | SK_USER_DATA_NOCOPY);
+
+	smc_clcsock_replace_cb(&clcsk->sk_state_change, smc_fback_state_change,
+			       &smc->clcsk_state_change);
+	smc_clcsock_replace_cb(&clcsk->sk_data_ready, smc_fback_data_ready,
+			       &smc->clcsk_data_ready);
+	smc_clcsock_replace_cb(&clcsk->sk_write_space, smc_fback_write_space,
+			       &smc->clcsk_write_space);
+	smc_clcsock_replace_cb(&clcsk->sk_error_report, smc_fback_error_report,
+			       &smc->clcsk_error_report);
+
+	write_unlock_bh(&clcsk->sk_callback_lock);
+}
+
+static void smc_switch_to_fallback(struct smc_sock *smc)
+{
 	smc->use_fallback = true;
 	if (smc->sk.sk_socket && smc->sk.sk_socket->file) {
 		smc->clcsock->file = smc->sk.sk_socket->file;
@@ -536,15 +675,11 @@ static void smc_switch_to_fallback(struct smc_sock *smc)
 		smc->clcsock->wq.fasync_list =
 			smc->sk.sk_socket->wq.fasync_list;
 
-		/* There may be some entries remaining in
-		 * smc socket->wq, which should be removed
-		 * to clcsocket->wq during the fallback.
+		/* There might be some wait entries remaining
+		 * in smc sk->sk_wq and they should be woken up
+		 * as clcsock's wait queue is woken up.
 		 */
-		spin_lock_irqsave(&smc_wait->lock, flags);
-		spin_lock_nested(&clc_wait->lock, SINGLE_DEPTH_NESTING);
-		list_splice_init(&smc_wait->head, &clc_wait->head);
-		spin_unlock(&clc_wait->lock);
-		spin_unlock_irqrestore(&smc_wait->lock, flags);
+		smc_fback_replace_callbacks(smc);
 	}
 }
 
@@ -1183,6 +1318,19 @@ static int smc_clcsock_accept(struct smc_sock *lsmc, struct smc_sock **new_smc)
 	 * function; switch it back to the original sk_data_ready function
 	 */
 	new_clcsock->sk->sk_data_ready = lsmc->clcsk_data_ready;
+
+	/* if new clcsock has also inherited the fallback-specific callback
+	 * functions, switch them back to the original ones.
+	 */
+	if (lsmc->use_fallback) {
+		if (lsmc->clcsk_state_change)
+			new_clcsock->sk->sk_state_change = lsmc->clcsk_state_change;
+		if (lsmc->clcsk_write_space)
+			new_clcsock->sk->sk_write_space = lsmc->clcsk_write_space;
+		if (lsmc->clcsk_error_report)
+			new_clcsock->sk->sk_error_report = lsmc->clcsk_error_report;
+	}
+
 	(*new_smc)->clcsock = new_clcsock;
 out:
 	return rc;
@@ -1845,16 +1993,18 @@ static void smc_clcsock_data_ready(struct sock *listen_clcsock)
 {
 	struct smc_sock *lsmc;
 
-	lsmc = (struct smc_sock *)
-	       ((uintptr_t)listen_clcsock->sk_user_data & ~SK_USER_DATA_NOCOPY);
+	read_lock_bh(&listen_clcsock->sk_callback_lock);
+	lsmc = smc_clcsock_user_data(listen_clcsock);
 	if (!lsmc)
-		return;
+		goto out;
 	lsmc->clcsk_data_ready(listen_clcsock);
 	if (lsmc->sk.sk_state == SMC_LISTEN) {
 		sock_hold(&lsmc->sk); /* sock_put in smc_tcp_listen_work() */
 		if (!queue_work(smc_hs_wq, &lsmc->tcp_listen_work))
 			sock_put(&lsmc->sk);
 	}
+out:
+	read_unlock_bh(&listen_clcsock->sk_callback_lock);
 }
 
 static int smc_listen(struct socket *sock, int backlog)
@@ -1886,13 +2036,20 @@ static int smc_listen(struct socket *sock, int backlog)
 	/* save original sk_data_ready function and establish
 	 * smc-specific sk_data_ready function
 	 */
-	smc->clcsk_data_ready = smc->clcsock->sk->sk_data_ready;
-	smc->clcsock->sk->sk_data_ready = smc_clcsock_data_ready;
+	write_lock_bh(&smc->clcsock->sk->sk_callback_lock);
 	smc->clcsock->sk->sk_user_data =
 		(void *)((uintptr_t)smc | SK_USER_DATA_NOCOPY);
+	smc_clcsock_replace_cb(&smc->clcsock->sk->sk_data_ready,
+			       smc_clcsock_data_ready, &smc->clcsk_data_ready);
+	write_unlock_bh(&smc->clcsock->sk->sk_callback_lock);
+
 	rc = kernel_listen(smc->clcsock, backlog);
 	if (rc) {
-		smc->clcsock->sk->sk_data_ready = smc->clcsk_data_ready;
+		write_lock_bh(&smc->clcsock->sk->sk_callback_lock);
+		smc_clcsock_restore_cb(&smc->clcsock->sk->sk_data_ready,
+				       &smc->clcsk_data_ready);
+		smc->clcsock->sk->sk_user_data = NULL;
+		write_unlock_bh(&smc->clcsock->sk->sk_callback_lock);
 		goto out;
 	}
 	sk->sk_max_ack_backlog = backlog;
diff --git a/net/smc/smc.h b/net/smc/smc.h
index e6919fe31617b5514657a6e8719da1fe414fb501..c06add7db4af2f1b463833e6ccdf5d2bf482338b 100644
--- a/net/smc/smc.h
+++ b/net/smc/smc.h
@@ -129,6 +129,12 @@ enum smc_urg_state {
 	SMC_URG_READ	= 3,			/* data was already read */
 };
 
+struct smc_mark_woken {
+	bool woken;
+	void *key;
+	wait_queue_entry_t wait_entry;
+};
+
 struct smc_connection {
 	struct rb_node		alert_node;
 	struct smc_link_group	*lgr;		/* link group of connection */
@@ -217,8 +223,14 @@ struct smc_connection {
 struct smc_sock {				/* smc sock container */
 	struct sock		sk;
 	struct socket		*clcsock;	/* internal tcp socket */
+	void			(*clcsk_state_change)(struct sock *sk);
+						/* original stat_change fct. */
 	void			(*clcsk_data_ready)(struct sock *sk);
-						/* original data_ready fct. **/
+						/* original data_ready fct. */
+	void			(*clcsk_write_space)(struct sock *sk);
+						/* original write_space fct. */
+	void			(*clcsk_error_report)(struct sock *sk);
+						/* original error_report fct. */
 	struct smc_connection	conn;		/* smc connection */
 	struct smc_sock		*listen_smc;	/* listen parent */
 	struct work_struct	connect_work;	/* handle non-blocking connect*/
@@ -253,6 +265,41 @@ static inline struct smc_sock *smc_sk(const struct sock *sk)
 	return (struct smc_sock *)sk;
 }
 
+static inline void smc_init_saved_callbacks(struct smc_sock *smc)
+{
+	smc->clcsk_state_change = NULL;
+	smc->clcsk_data_ready   = NULL;
+	smc->clcsk_write_space  = NULL;
+	smc->clcsk_error_report = NULL;
+}
+
+static inline struct smc_sock *smc_clcsock_user_data(struct sock *clcsk)
+{
+	return (struct smc_sock *)
+	       ((uintptr_t)clcsk->sk_user_data & ~SK_USER_DATA_NOCOPY);
+}
+
+/* save target_cb in saved_cb, and replace target_cb with new_cb */
+static inline void smc_clcsock_replace_cb(void (**target_cb)(struct sock *),
+					  void (*new_cb)(struct sock *),
+					  void (**saved_cb)(struct sock *))
+{
+	/* only save once */
+	if (!*saved_cb)
+		*saved_cb = *target_cb;
+	*target_cb = new_cb;
+}
+
+/* restore target_cb to saved_cb, and reset saved_cb to NULL */
+static inline void smc_clcsock_restore_cb(void (**target_cb)(struct sock *),
+					  void (**saved_cb)(struct sock *))
+{
+	if (!*saved_cb)
+		return;
+	*target_cb = *saved_cb;
+	*saved_cb = NULL;
+}
+
 extern struct workqueue_struct	*smc_hs_wq;	/* wq for handshake work */
 extern struct workqueue_struct	*smc_close_wq;	/* wq for close work */
 
diff --git a/net/smc/smc_close.c b/net/smc/smc_close.c
index 84102db5bb31452ed1e8aec94514418e4741d464..fef8af2ccaadfa24bccd59602795d65947d2965c 100644
--- a/net/smc/smc_close.c
+++ b/net/smc/smc_close.c
@@ -211,8 +211,11 @@ int smc_close_active(struct smc_sock *smc)
 		sk->sk_state = SMC_CLOSED;
 		sk->sk_state_change(sk); /* wake up accept */
 		if (smc->clcsock && smc->clcsock->sk) {
-			smc->clcsock->sk->sk_data_ready = smc->clcsk_data_ready;
+			write_lock_bh(&smc->clcsock->sk->sk_callback_lock);
+			smc_clcsock_restore_cb(&smc->clcsock->sk->sk_data_ready,
+					       &smc->clcsk_data_ready);
 			smc->clcsock->sk->sk_user_data = NULL;
+			write_unlock_bh(&smc->clcsock->sk->sk_callback_lock);
 			rc = kernel_sock_shutdown(smc->clcsock, SHUT_RDWR);
 		}
 		smc_close_cleanup_listen(sk);