[patch 0/2] [AF_IUCV] fixes for net-2.6.24

[patch 0/2] [AF_IUCV] fixes for net-2.6.24

[Ursula Braun]

-- 
Dave,

the following 2 patches are intended for 2.6.24 and contain:
- removal of static declarations in af_iucv header file
- postpone receival of inbound packets in af_iucv

[patch 1/2] af_iucv: remove static declarations from header file.

[Ursula Braun]

[-- Attachment #1: 711-afiucv-statics.diff --]
[-- Type: text/plain, Size: 2543 bytes --]

From: Heiko Carstens <heiko.carstens@de.ibm.com>

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Ursula Braun <braunu@de.ibm.com>
---

 include/net/iucv/af_iucv.h |   21 ---------------------
 net/iucv/af_iucv.c         |    3 +++
 2 files changed, 3 insertions(+), 21 deletions(-)

Index: net-2.6-uschi/include/net/iucv/af_iucv.h
===================================================================
--- net-2.6-uschi.orig/include/net/iucv/af_iucv.h
+++ net-2.6-uschi/include/net/iucv/af_iucv.h
@@ -73,29 +73,8 @@ struct iucv_sock_list {
 	atomic_t	  autobind_name;
 };
 
-static void iucv_sock_destruct(struct sock *sk);
-static void iucv_sock_cleanup_listen(struct sock *parent);
-static void iucv_sock_kill(struct sock *sk);
-static void iucv_sock_close(struct sock *sk);
-static int  iucv_sock_create(struct socket *sock, int proto);
-static int  iucv_sock_bind(struct socket *sock, struct sockaddr *addr,
-			int addr_len);
-static int  iucv_sock_connect(struct socket *sock, struct sockaddr *addr,
-			      int alen, int flags);
-static int  iucv_sock_listen(struct socket *sock, int backlog);
-static int  iucv_sock_accept(struct socket *sock, struct socket *newsock,
-			     int flags);
-static int  iucv_sock_getname(struct socket *sock, struct sockaddr *addr,
-			      int *len, int peer);
-static int  iucv_sock_sendmsg(struct kiocb *iocb, struct socket *sock,
-			      struct msghdr *msg, size_t len);
-static int  iucv_sock_recvmsg(struct kiocb *iocb, struct socket *sock,
-			      struct msghdr *msg, size_t len, int flags);
 unsigned int iucv_sock_poll(struct file *file, struct socket *sock,
 			    poll_table *wait);
-static int iucv_sock_release(struct socket *sock);
-static int iucv_sock_shutdown(struct socket *sock, int how);
-
 void iucv_sock_link(struct iucv_sock_list *l, struct sock *s);
 void iucv_sock_unlink(struct iucv_sock_list *l, struct sock *s);
 int  iucv_sock_wait_state(struct sock *sk, int state, int state2,
Index: net-2.6-uschi/net/iucv/af_iucv.c
===================================================================
--- net-2.6-uschi.orig/net/iucv/af_iucv.c
+++ net-2.6-uschi/net/iucv/af_iucv.c
@@ -41,6 +41,9 @@ static struct proto iucv_proto = {
 	.obj_size	= sizeof(struct iucv_sock),
 };
 
+static void iucv_sock_kill(struct sock *sk);
+static void iucv_sock_close(struct sock *sk);
+
 /* Call Back functions */
 static void iucv_callback_rx(struct iucv_path *, struct iucv_message *);
 static void iucv_callback_txdone(struct iucv_path *, struct iucv_message *);

-- 

[patch 2/2] af_iucv: postpone receival of iucv-packets

[Ursula Braun]

[-- Attachment #1: 712-afiucv-throttle.diff --]
[-- Type: text/plain, Size: 8576 bytes --]

From: Ursula Braun <braunu@de.ibm.com>

AF_IUCV socket programs may waste Linux storage, because af_iucv
allocates an skb whenever posted by the receive callback routine and
receives the message immediately. 
Message receival is now postponed if data from previous callbacks has 
not yet been transferred to the receiving socket program. Instead a 
message handle is saved in a message queue as a reminder. Once 
messages could be given to the receiving socket program, there is 
an additional checking for entries in the message queue, followed
by skb allocation and message receival if applicable.

Signed-off-by: Ursula Braun <braunu@de.ibm.com>
---

 include/net/iucv/af_iucv.h |    7 +
 net/iucv/af_iucv.c         |  215 ++++++++++++++++++++++++++-------------------
 2 files changed, 134 insertions(+), 88 deletions(-)

Index: net-2.6-uschi/include/net/iucv/af_iucv.h
===================================================================
--- net-2.6-uschi.orig/include/net/iucv/af_iucv.h
+++ net-2.6-uschi/include/net/iucv/af_iucv.h
@@ -50,6 +50,12 @@ struct sockaddr_iucv {
 
 
 /* Common socket structures and functions */
+struct sock_msg_q {
+	struct iucv_path	*path;
+	struct iucv_message	msg;
+	struct list_head	list;
+	spinlock_t		lock;
+};
 
 #define iucv_sk(__sk) ((struct iucv_sock *) __sk)
 
@@ -64,6 +70,7 @@ struct iucv_sock {
 	struct iucv_path	*path;
 	struct sk_buff_head	send_skb_q;
 	struct sk_buff_head	backlog_skb_q;
+	struct sock_msg_q	message_q;
 	unsigned int		send_tag;
 };
 
Index: net-2.6-uschi/net/iucv/af_iucv.c
===================================================================
--- net-2.6-uschi.orig/net/iucv/af_iucv.c
+++ net-2.6-uschi/net/iucv/af_iucv.c
@@ -223,6 +223,8 @@ static struct sock *iucv_sock_alloc(stru
 	sock_init_data(sock, sk);
 	INIT_LIST_HEAD(&iucv_sk(sk)->accept_q);
 	skb_queue_head_init(&iucv_sk(sk)->send_skb_q);
+	INIT_LIST_HEAD(&iucv_sk(sk)->message_q.list);
+	spin_lock_init(&iucv_sk(sk)->message_q.lock);
 	skb_queue_head_init(&iucv_sk(sk)->backlog_skb_q);
 	iucv_sk(sk)->send_tag = 0;
 
@@ -662,6 +664,90 @@ out:
 	return err;
 }
 
+static int iucv_fragment_skb(struct sock *sk, struct sk_buff *skb, int len)
+{
+	int dataleft, size, copied = 0;
+	struct sk_buff *nskb;
+
+	dataleft = len;
+	while (dataleft) {
+		if (dataleft >= sk->sk_rcvbuf / 4)
+			size = sk->sk_rcvbuf / 4;
+		else
+			size = dataleft;
+
+		nskb = alloc_skb(size, GFP_ATOMIC | GFP_DMA);
+		if (!nskb)
+			return -ENOMEM;
+
+		memcpy(nskb->data, skb->data + copied, size);
+		copied += size;
+		dataleft -= size;
+
+		skb_reset_transport_header(nskb);
+		skb_reset_network_header(nskb);
+		nskb->len = size;
+
+		skb_queue_tail(&iucv_sk(sk)->backlog_skb_q, nskb);
+	}
+
+	return 0;
+}
+
+static void iucv_process_message(struct sock *sk, struct sk_buff *skb,
+				 struct iucv_path *path,
+				 struct iucv_message *msg)
+{
+	int rc;
+
+	if (msg->flags & IPRMDATA) {
+		skb->data = NULL;
+		skb->len = 0;
+	} else {
+		rc = iucv_message_receive(path, msg, 0, skb->data,
+					  msg->length, NULL);
+		if (rc) {
+			kfree_skb(skb);
+			return;
+		}
+		if (skb->truesize >= sk->sk_rcvbuf / 4) {
+			rc = iucv_fragment_skb(sk, skb, msg->length);
+			kfree_skb(skb);
+			skb = NULL;
+			if (rc) {
+				iucv_path_sever(path, NULL);
+				return;
+			}
+			skb = skb_dequeue(&iucv_sk(sk)->backlog_skb_q);
+		} else {
+			skb_reset_transport_header(skb);
+			skb_reset_network_header(skb);
+			skb->len = msg->length;
+		}
+	}
+
+	if (sock_queue_rcv_skb(sk, skb))
+		skb_queue_head(&iucv_sk(sk)->backlog_skb_q, skb);
+}
+
+static void iucv_process_message_q(struct sock *sk)
+{
+	struct iucv_sock *iucv = iucv_sk(sk);
+	struct sk_buff *skb;
+	struct sock_msg_q *p, *n;
+
+	list_for_each_entry_safe(p, n, &iucv->message_q.list, list) {
+		skb = alloc_skb(p->msg.length, GFP_ATOMIC | GFP_DMA);
+		if (!skb)
+			break;
+		iucv_process_message(sk, skb, p->path, &p->msg);
+		list_del(&p->list);
+		kfree(p);
+		if (!skb_queue_empty(&iucv->backlog_skb_q))
+			break;
+	}
+}
+
 static int iucv_sock_recvmsg(struct kiocb *iocb, struct socket *sock,
 			     struct msghdr *msg, size_t len, int flags)
 {
@@ -673,8 +759,9 @@ static int iucv_sock_recvmsg(struct kioc
 	int err = 0;
 
 	if ((sk->sk_state == IUCV_DISCONN || sk->sk_state == IUCV_SEVERED) &&
-		skb_queue_empty(&iucv->backlog_skb_q) &&
-		skb_queue_empty(&sk->sk_receive_queue))
+	    skb_queue_empty(&iucv->backlog_skb_q) &&
+	    skb_queue_empty(&sk->sk_receive_queue) &&
+	    list_empty(&iucv->message_q.list))
 		return 0;
 
 	if (flags & (MSG_OOB))
@@ -713,16 +800,23 @@ static int iucv_sock_recvmsg(struct kioc
 		kfree_skb(skb);
 
 		/* Queue backlog skbs */
-		rskb = skb_dequeue(&iucv_sk(sk)->backlog_skb_q);
+		rskb = skb_dequeue(&iucv->backlog_skb_q);
 		while (rskb) {
 			if (sock_queue_rcv_skb(sk, rskb)) {
-				skb_queue_head(&iucv_sk(sk)->backlog_skb_q,
+				skb_queue_head(&iucv->backlog_skb_q,
 						rskb);
 				break;
 			} else {
-				rskb = skb_dequeue(&iucv_sk(sk)->backlog_skb_q);
+				rskb = skb_dequeue(&iucv->backlog_skb_q);
 			}
 		}
+		if (skb_queue_empty(&iucv->backlog_skb_q)) {
+			spin_lock_bh(&iucv->message_q.lock);
+			if (!list_empty(&iucv->message_q.list))
+				iucv_process_message_q(sk);
+			spin_unlock_bh(&iucv->message_q.lock);
+		}
+
 	} else
 		skb_queue_head(&sk->sk_receive_queue, skb);
 
@@ -963,99 +1057,44 @@ static void iucv_callback_connack(struct
 	sk->sk_state_change(sk);
 }
 
-static int iucv_fragment_skb(struct sock *sk, struct sk_buff *skb, int len,
-			     struct sk_buff_head *fragmented_skb_q)
-{
-	int dataleft, size, copied = 0;
-	struct sk_buff *nskb;
-
-	dataleft = len;
-	while (dataleft) {
-		if (dataleft >= sk->sk_rcvbuf / 4)
-			size = sk->sk_rcvbuf / 4;
-		else
-			size = dataleft;
-
-		nskb = alloc_skb(size, GFP_ATOMIC | GFP_DMA);
-		if (!nskb)
-			return -ENOMEM;
-
-		memcpy(nskb->data, skb->data + copied, size);
-		copied += size;
-		dataleft -= size;
-
-		skb_reset_transport_header(nskb);
-		skb_reset_network_header(nskb);
-		nskb->len = size;
-
-		skb_queue_tail(fragmented_skb_q, nskb);
-	}
-
-	return 0;
-}
-
 static void iucv_callback_rx(struct iucv_path *path, struct iucv_message *msg)
 {
 	struct sock *sk = path->private;
 	struct iucv_sock *iucv = iucv_sk(sk);
-	struct sk_buff *skb, *fskb;
-	struct sk_buff_head fragmented_skb_q;
-	int rc;
-
-	skb_queue_head_init(&fragmented_skb_q);
+	struct sk_buff *skb;
+	struct sock_msg_q *save_msg;
+	int len;
 
 	if (sk->sk_shutdown & RCV_SHUTDOWN)
 		return;
 
-	skb = alloc_skb(msg->length, GFP_ATOMIC | GFP_DMA);
-	if (!skb) {
-		iucv_path_sever(path, NULL);
-		return;
-	}
+	if (!list_empty(&iucv->message_q.list) ||
+	    !skb_queue_empty(&iucv->backlog_skb_q))
+		goto save_message;
+
+	len = atomic_read(&sk->sk_rmem_alloc);
+	len += msg->length + sizeof(struct sk_buff);
+	if (len > sk->sk_rcvbuf)
+		goto save_message;
 
-	if (msg->flags & IPRMDATA) {
-		skb->data = NULL;
-		skb->len = 0;
-	} else {
-		rc = iucv_message_receive(path, msg, 0, skb->data,
-					  msg->length, NULL);
-		if (rc) {
-			kfree_skb(skb);
-			return;
-		}
-		if (skb->truesize >= sk->sk_rcvbuf / 4) {
-			rc = iucv_fragment_skb(sk, skb, msg->length,
-					       &fragmented_skb_q);
-			kfree_skb(skb);
-			skb = NULL;
-			if (rc) {
-				iucv_path_sever(path, NULL);
-				return;
-			}
-		} else {
-			skb_reset_transport_header(skb);
-			skb_reset_network_header(skb);
-			skb->len = msg->length;
-		}
-	}
-	/* Queue the fragmented skb */
-	fskb = skb_dequeue(&fragmented_skb_q);
-	while (fskb) {
-		if (!skb_queue_empty(&iucv->backlog_skb_q))
-			skb_queue_tail(&iucv->backlog_skb_q, fskb);
-		else if (sock_queue_rcv_skb(sk, fskb))
-			skb_queue_tail(&iucv_sk(sk)->backlog_skb_q, fskb);
-		fskb = skb_dequeue(&fragmented_skb_q);
-	}
-
-	/* Queue the original skb if it exists (was not fragmented) */
-	if (skb) {
-		if (!skb_queue_empty(&iucv->backlog_skb_q))
-			skb_queue_tail(&iucv_sk(sk)->backlog_skb_q, skb);
-		else if (sock_queue_rcv_skb(sk, skb))
-			skb_queue_tail(&iucv_sk(sk)->backlog_skb_q, skb);
-	}
+	skb = alloc_skb(msg->length, GFP_ATOMIC | GFP_DMA);
+	if (!skb)
+		goto save_message;
 
+	spin_lock(&iucv->message_q.lock);
+	iucv_process_message(sk, skb, path, msg);
+	spin_unlock(&iucv->message_q.lock);
+
+	return;
+
+save_message:
+	save_msg = kzalloc(sizeof(struct sock_msg_q), GFP_ATOMIC | GFP_DMA);
+	save_msg->path = path;
+	save_msg->msg = *msg;
+
+	spin_lock(&iucv->message_q.lock);
+	list_add_tail(&save_msg->list, &iucv->message_q.list);
+	spin_unlock(&iucv->message_q.lock);
 }
 
 static void iucv_callback_txdone(struct iucv_path *path,

-- 

Re: [patch 0/2] [AF_IUCV] fixes for net-2.6.24

[David Miller]

From: Ursula Braun <braunu@de.ibm.com>
Date: Thu, 04 Oct 2007 16:46:08 +0200

> the following 2 patches are intended for 2.6.24 and contain:
> - removal of static declarations in af_iucv header file
> - postpone receival of inbound packets in af_iucv

These patches don't apply, for one thing the first patch
rejects because the net-2.6.24 copy of include/net/iucv/af_iucv.h
has this line:

+static int  iucv_sock_create(struct socket *sock, int proto);

but the file you are patching against does not.

Please generate new clean patches against net-2.6.24, thank you.

[patch 0/2] [AF_IUCV] fixes for net-2.6.24 - cleanup resend

[Ursula Braun]

-- 
Dave,

this is the resend of my patches from last week built against net-2.6.24.

> the following 2 patches are intended for 2.6.24 and contain:
> - removal of static declarations in af_iucv header file
> - postpone receival of inbound packets in af_iucv

Regards, Ursula

[patch 2/2] af_iucv: postpone receival of iucv-packets

[Ursula Braun]

[-- Attachment #1: 712-afiucv-throttle.diff --]
[-- Type: text/plain, Size: 8613 bytes --]

From: Ursula Braun <braunu@de.ibm.com>

AF_IUCV socket programs may waste Linux storage, because af_iucv
allocates an skb whenever posted by the receive callback routine and
receives the message immediately. 
Message receival is now postponed if data from previous callbacks has 
not yet been transferred to the receiving socket program. Instead a 
message handle is saved in a message queue as a reminder. Once 
messages could be given to the receiving socket program, there is 
an additional checking for entries in the message queue, followed
by skb allocation and message receival if applicable.

Signed-off-by: Ursula Braun <braunu@de.ibm.com>
---

 include/net/iucv/af_iucv.h |    7 +
 net/iucv/af_iucv.c         |  215 ++++++++++++++++++++++++++-------------------
 2 files changed, 134 insertions(+), 88 deletions(-)

Index: net-2.6.24-uschi/include/net/iucv/af_iucv.h
===================================================================
--- net-2.6.24-uschi.orig/include/net/iucv/af_iucv.h
+++ net-2.6.24-uschi/include/net/iucv/af_iucv.h
@@ -50,6 +50,12 @@ struct sockaddr_iucv {
 
 
 /* Common socket structures and functions */
+struct sock_msg_q {
+	struct iucv_path	*path;
+	struct iucv_message	msg;
+	struct list_head	list;
+	spinlock_t		lock;
+};
 
 #define iucv_sk(__sk) ((struct iucv_sock *) __sk)
 
@@ -65,6 +71,7 @@ struct iucv_sock {
 	struct iucv_path	*path;
 	struct sk_buff_head	send_skb_q;
 	struct sk_buff_head	backlog_skb_q;
+	struct sock_msg_q	message_q;
 	unsigned int		send_tag;
 };
 
Index: net-2.6.24-uschi/net/iucv/af_iucv.c
===================================================================
--- net-2.6.24-uschi.orig/net/iucv/af_iucv.c
+++ net-2.6.24-uschi/net/iucv/af_iucv.c
@@ -224,6 +224,8 @@ static struct sock *iucv_sock_alloc(stru
 	INIT_LIST_HEAD(&iucv_sk(sk)->accept_q);
 	spin_lock_init(&iucv_sk(sk)->accept_q_lock);
 	skb_queue_head_init(&iucv_sk(sk)->send_skb_q);
+	INIT_LIST_HEAD(&iucv_sk(sk)->message_q.list);
+	spin_lock_init(&iucv_sk(sk)->message_q.lock);
 	skb_queue_head_init(&iucv_sk(sk)->backlog_skb_q);
 	iucv_sk(sk)->send_tag = 0;
 
@@ -673,6 +675,90 @@ out:
 	return err;
 }
 
+static int iucv_fragment_skb(struct sock *sk, struct sk_buff *skb, int len)
+{
+	int dataleft, size, copied = 0;
+	struct sk_buff *nskb;
+
+	dataleft = len;
+	while (dataleft) {
+		if (dataleft >= sk->sk_rcvbuf / 4)
+			size = sk->sk_rcvbuf / 4;
+		else
+			size = dataleft;
+
+		nskb = alloc_skb(size, GFP_ATOMIC | GFP_DMA);
+		if (!nskb)
+			return -ENOMEM;
+
+		memcpy(nskb->data, skb->data + copied, size);
+		copied += size;
+		dataleft -= size;
+
+		skb_reset_transport_header(nskb);
+		skb_reset_network_header(nskb);
+		nskb->len = size;
+
+		skb_queue_tail(&iucv_sk(sk)->backlog_skb_q, nskb);
+	}
+
+	return 0;
+}
+
+static void iucv_process_message(struct sock *sk, struct sk_buff *skb,
+				 struct iucv_path *path,
+				 struct iucv_message *msg)
+{
+	int rc;
+
+	if (msg->flags & IPRMDATA) {
+		skb->data = NULL;
+		skb->len = 0;
+	} else {
+		rc = iucv_message_receive(path, msg, 0, skb->data,
+					  msg->length, NULL);
+		if (rc) {
+			kfree_skb(skb);
+			return;
+		}
+		if (skb->truesize >= sk->sk_rcvbuf / 4) {
+			rc = iucv_fragment_skb(sk, skb, msg->length);
+			kfree_skb(skb);
+			skb = NULL;
+			if (rc) {
+				iucv_path_sever(path, NULL);
+				return;
+			}
+			skb = skb_dequeue(&iucv_sk(sk)->backlog_skb_q);
+		} else {
+			skb_reset_transport_header(skb);
+			skb_reset_network_header(skb);
+			skb->len = msg->length;
+		}
+	}
+
+	if (sock_queue_rcv_skb(sk, skb))
+		skb_queue_head(&iucv_sk(sk)->backlog_skb_q, skb);
+}
+
+static void iucv_process_message_q(struct sock *sk)
+{
+	struct iucv_sock *iucv = iucv_sk(sk);
+	struct sk_buff *skb;
+	struct sock_msg_q *p, *n;
+
+	list_for_each_entry_safe(p, n, &iucv->message_q.list, list) {
+		skb = alloc_skb(p->msg.length, GFP_ATOMIC | GFP_DMA);
+		if (!skb)
+			break;
+		iucv_process_message(sk, skb, p->path, &p->msg);
+		list_del(&p->list);
+		kfree(p);
+		if (!skb_queue_empty(&iucv->backlog_skb_q))
+			break;
+	}
+}
+
 static int iucv_sock_recvmsg(struct kiocb *iocb, struct socket *sock,
 			     struct msghdr *msg, size_t len, int flags)
 {
@@ -684,8 +770,9 @@ static int iucv_sock_recvmsg(struct kioc
 	int err = 0;
 
 	if ((sk->sk_state == IUCV_DISCONN || sk->sk_state == IUCV_SEVERED) &&
-		skb_queue_empty(&iucv->backlog_skb_q) &&
-		skb_queue_empty(&sk->sk_receive_queue))
+	    skb_queue_empty(&iucv->backlog_skb_q) &&
+	    skb_queue_empty(&sk->sk_receive_queue) &&
+	    list_empty(&iucv->message_q.list))
 		return 0;
 
 	if (flags & (MSG_OOB))
@@ -724,16 +811,23 @@ static int iucv_sock_recvmsg(struct kioc
 		kfree_skb(skb);
 
 		/* Queue backlog skbs */
-		rskb = skb_dequeue(&iucv_sk(sk)->backlog_skb_q);
+		rskb = skb_dequeue(&iucv->backlog_skb_q);
 		while (rskb) {
 			if (sock_queue_rcv_skb(sk, rskb)) {
-				skb_queue_head(&iucv_sk(sk)->backlog_skb_q,
+				skb_queue_head(&iucv->backlog_skb_q,
 						rskb);
 				break;
 			} else {
-				rskb = skb_dequeue(&iucv_sk(sk)->backlog_skb_q);
+				rskb = skb_dequeue(&iucv->backlog_skb_q);
 			}
 		}
+		if (skb_queue_empty(&iucv->backlog_skb_q)) {
+			spin_lock_bh(&iucv->message_q.lock);
+			if (!list_empty(&iucv->message_q.list))
+				iucv_process_message_q(sk);
+			spin_unlock_bh(&iucv->message_q.lock);
+		}
+
 	} else
 		skb_queue_head(&sk->sk_receive_queue, skb);
 
@@ -975,99 +1069,44 @@ static void iucv_callback_connack(struct
 	sk->sk_state_change(sk);
 }
 
-static int iucv_fragment_skb(struct sock *sk, struct sk_buff *skb, int len,
-			     struct sk_buff_head *fragmented_skb_q)
-{
-	int dataleft, size, copied = 0;
-	struct sk_buff *nskb;
-
-	dataleft = len;
-	while (dataleft) {
-		if (dataleft >= sk->sk_rcvbuf / 4)
-			size = sk->sk_rcvbuf / 4;
-		else
-			size = dataleft;
-
-		nskb = alloc_skb(size, GFP_ATOMIC | GFP_DMA);
-		if (!nskb)
-			return -ENOMEM;
-
-		memcpy(nskb->data, skb->data + copied, size);
-		copied += size;
-		dataleft -= size;
-
-		skb_reset_transport_header(nskb);
-		skb_reset_network_header(nskb);
-		nskb->len = size;
-
-		skb_queue_tail(fragmented_skb_q, nskb);
-	}
-
-	return 0;
-}
-
 static void iucv_callback_rx(struct iucv_path *path, struct iucv_message *msg)
 {
 	struct sock *sk = path->private;
 	struct iucv_sock *iucv = iucv_sk(sk);
-	struct sk_buff *skb, *fskb;
-	struct sk_buff_head fragmented_skb_q;
-	int rc;
-
-	skb_queue_head_init(&fragmented_skb_q);
+	struct sk_buff *skb;
+	struct sock_msg_q *save_msg;
+	int len;
 
 	if (sk->sk_shutdown & RCV_SHUTDOWN)
 		return;
 
-	skb = alloc_skb(msg->length, GFP_ATOMIC | GFP_DMA);
-	if (!skb) {
-		iucv_path_sever(path, NULL);
-		return;
-	}
+	if (!list_empty(&iucv->message_q.list) ||
+	    !skb_queue_empty(&iucv->backlog_skb_q))
+		goto save_message;
+
+	len = atomic_read(&sk->sk_rmem_alloc);
+	len += msg->length + sizeof(struct sk_buff);
+	if (len > sk->sk_rcvbuf)
+		goto save_message;
 
-	if (msg->flags & IPRMDATA) {
-		skb->data = NULL;
-		skb->len = 0;
-	} else {
-		rc = iucv_message_receive(path, msg, 0, skb->data,
-					  msg->length, NULL);
-		if (rc) {
-			kfree_skb(skb);
-			return;
-		}
-		if (skb->truesize >= sk->sk_rcvbuf / 4) {
-			rc = iucv_fragment_skb(sk, skb, msg->length,
-					       &fragmented_skb_q);
-			kfree_skb(skb);
-			skb = NULL;
-			if (rc) {
-				iucv_path_sever(path, NULL);
-				return;
-			}
-		} else {
-			skb_reset_transport_header(skb);
-			skb_reset_network_header(skb);
-			skb->len = msg->length;
-		}
-	}
-	/* Queue the fragmented skb */
-	fskb = skb_dequeue(&fragmented_skb_q);
-	while (fskb) {
-		if (!skb_queue_empty(&iucv->backlog_skb_q))
-			skb_queue_tail(&iucv->backlog_skb_q, fskb);
-		else if (sock_queue_rcv_skb(sk, fskb))
-			skb_queue_tail(&iucv_sk(sk)->backlog_skb_q, fskb);
-		fskb = skb_dequeue(&fragmented_skb_q);
-	}
-
-	/* Queue the original skb if it exists (was not fragmented) */
-	if (skb) {
-		if (!skb_queue_empty(&iucv->backlog_skb_q))
-			skb_queue_tail(&iucv_sk(sk)->backlog_skb_q, skb);
-		else if (sock_queue_rcv_skb(sk, skb))
-			skb_queue_tail(&iucv_sk(sk)->backlog_skb_q, skb);
-	}
+	skb = alloc_skb(msg->length, GFP_ATOMIC | GFP_DMA);
+	if (!skb)
+		goto save_message;
 
+	spin_lock(&iucv->message_q.lock);
+	iucv_process_message(sk, skb, path, msg);
+	spin_unlock(&iucv->message_q.lock);
+
+	return;
+
+save_message:
+	save_msg = kzalloc(sizeof(struct sock_msg_q), GFP_ATOMIC | GFP_DMA);
+	save_msg->path = path;
+	save_msg->msg = *msg;
+
+	spin_lock(&iucv->message_q.lock);
+	list_add_tail(&save_msg->list, &iucv->message_q.list);
+	spin_unlock(&iucv->message_q.lock);
 }
 
 static void iucv_callback_txdone(struct iucv_path *path,

--