[AF_IUCV]: Implementation of a skb backlog queue

With the inital implementation we missed to implement a skb backlog
queue . The result is that socket receive processing tossed packets.
Since AF_IUCV connections are working synchronously it leads to
connection hangs. Problems with read, close and select also occured.

Using a skb backlog queue is fixing all of these problems .

Signed-off-by: Jennifer Hunt <jenhunt@us.ibm.com>
Signed-off-by: Frank Pavlic <fpavlic@de.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 132 insertions, 29 deletions

diff --git a/include/net/iucv/af_iucv.h b/include/net/iucv/af_iucv.h
index 04d1abb72d25..f9bd11be1891 100644
--- a/include/net/iucv/af_iucv.h
+++ b/include/net/iucv/af_iucv.h
@@ -28,6 +28,7 @@ enum {
         IUCV_LISTEN,
         IUCV_SEVERED,
         IUCV_DISCONN,
+        IUCV_CLOSING,
         IUCV_CLOSED
 };
 
@@ -62,6 +63,7 @@ struct iucv_sock {
         struct sock             *parent;
         struct iucv_path        *path;
         struct sk_buff_head     send_skb_q;
+        struct sk_buff_head     backlog_skb_q;
         unsigned int            send_tag;
 };
 
diff --git a/net/iucv/af_iucv.c b/net/iucv/af_iucv.c
index e84c924a81ee..026704a47296 100644
--- a/net/iucv/af_iucv.c
+++ b/net/iucv/af_iucv.c
@@ -147,6 +147,7 @@ static void iucv_sock_close(struct sock *sk)
         unsigned char user_data[16];
         struct iucv_sock *iucv = iucv_sk(sk);
         int err;
+        unsigned long timeo;
 
         iucv_sock_clear_timer(sk);
         lock_sock(sk);
@@ -159,6 +160,21 @@ static void iucv_sock_close(struct sock *sk)
         case IUCV_CONNECTED:
         case IUCV_DISCONN:
                 err = 0;
+
+                sk->sk_state = IUCV_CLOSING;
+                sk->sk_state_change(sk);
+
+                if(!skb_queue_empty(&iucv->send_skb_q)) {
+                        if (sock_flag(sk, SOCK_LINGER) && sk->sk_lingertime)
+                                timeo = sk->sk_lingertime;
+                        else
+                                timeo = IUCV_DISCONN_TIMEOUT;
+                        err = iucv_sock_wait_state(sk, IUCV_CLOSED, 0, timeo);
+                }
+
+                sk->sk_state = IUCV_CLOSED;
+                sk->sk_state_change(sk);
+
                 if (iucv->path) {
                         low_nmcpy(user_data, iucv->src_name);
                         high_nmcpy(user_data, iucv->dst_name);
@@ -168,12 +184,11 @@ static void iucv_sock_close(struct sock *sk)
                         iucv->path = NULL;
                 }
 
-                sk->sk_state = IUCV_CLOSED;
-                sk->sk_state_change(sk);
                 sk->sk_err = ECONNRESET;
                 sk->sk_state_change(sk);
 
                 skb_queue_purge(&iucv->send_skb_q);
+                skb_queue_purge(&iucv->backlog_skb_q);
 
                 sock_set_flag(sk, SOCK_ZAPPED);
                 break;
@@ -204,6 +219,7 @@ static struct sock *iucv_sock_alloc(struct socket *sock, int proto, gfp_t prio)
         sock_init_data(sock, sk);
         INIT_LIST_HEAD(&iucv_sk(sk)->accept_q);
         skb_queue_head_init(&iucv_sk(sk)->send_skb_q);
+        skb_queue_head_init(&iucv_sk(sk)->backlog_skb_q);
         iucv_sk(sk)->send_tag = 0;
 
         sk->sk_destruct = iucv_sock_destruct;
@@ -510,7 +526,7 @@ static int iucv_sock_accept(struct socket *sock, struct socket *newsock,
         long timeo;
         int err = 0;
 
-        lock_sock(sk);
+        lock_sock_nested(sk, SINGLE_DEPTH_NESTING);
 
         if (sk->sk_state != IUCV_LISTEN) {
                 err = -EBADFD;
@@ -530,7 +546,7 @@ static int iucv_sock_accept(struct socket *sock, struct socket *newsock,
 
                 release_sock(sk);
                 timeo = schedule_timeout(timeo);
-                lock_sock(sk);
+                lock_sock_nested(sk, SINGLE_DEPTH_NESTING);
 
                 if (sk->sk_state != IUCV_LISTEN) {
                         err = -EBADFD;
@@ -606,7 +622,7 @@ static int iucv_sock_sendmsg(struct kiocb *iocb, struct socket *sock,
                 if(!(skb = sock_alloc_send_skb(sk, len,
                                        msg->msg_flags & MSG_DONTWAIT,
                                        &err)))
-                        return err;
+                        goto out;
 
                 if (memcpy_fromiovec(skb_put(skb, len), msg->msg_iov, len)){
                         err = -EFAULT;
@@ -647,10 +663,16 @@ static int iucv_sock_recvmsg(struct kiocb *iocb, struct socket *sock,
 {
         int noblock = flags & MSG_DONTWAIT;
         struct sock *sk = sock->sk;
+        struct iucv_sock *iucv = iucv_sk(sk);
         int target, copied = 0;
-        struct sk_buff *skb;
+        struct sk_buff *skb, *rskb, *cskb;
         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))
+                return 0;
+
         if (flags & (MSG_OOB))
                 return -EOPNOTSUPP;
 
@@ -665,10 +687,12 @@ static int iucv_sock_recvmsg(struct kiocb *iocb, struct socket *sock,
 
         copied = min_t(unsigned int, skb->len, len);
 
-        if (memcpy_toiovec(msg->msg_iov, skb->data, copied)) {
+        cskb = skb;
+        if (memcpy_toiovec(msg->msg_iov, cskb->data, copied)) {
                 skb_queue_head(&sk->sk_receive_queue, skb);
                 if (copied == 0)
                         return -EFAULT;
+                goto done;
         }
 
         len -= copied;
@@ -683,6 +707,18 @@ static int iucv_sock_recvmsg(struct kiocb *iocb, struct socket *sock,
                 }
 
                 kfree_skb(skb);
+
+                /* Queue backlog skbs */
+                rskb = skb_dequeue(&iucv_sk(sk)->backlog_skb_q);
+                while(rskb) {
+                        if (sock_queue_rcv_skb(sk, rskb)) {
+                                skb_queue_head(&iucv_sk(sk)->backlog_skb_q,
+                                                rskb);
+                                break;
+                        } else {
+                                rskb = skb_dequeue(&iucv_sk(sk)->backlog_skb_q);
+                        }
+                }
         } else
                 skb_queue_head(&sk->sk_receive_queue, skb);
 
@@ -732,6 +768,9 @@ unsigned int iucv_sock_poll(struct file *file, struct socket *sock,
         if (sk->sk_state == IUCV_CLOSED)
                 mask |= POLLHUP;
 
+        if (sk->sk_state == IUCV_DISCONN || sk->sk_state == IUCV_SEVERED)
+                mask |= POLLIN;
+
         if (sock_writeable(sk))
                 mask |= POLLOUT | POLLWRNORM | POLLWRBAND;
         else
@@ -817,13 +856,6 @@ static int iucv_sock_release(struct socket *sock)
                 iucv_sk(sk)->path = NULL;
         }
 
-        if (sock_flag(sk, SOCK_LINGER) && sk->sk_lingertime){
-                lock_sock(sk);
-                err = iucv_sock_wait_state(sk, IUCV_CLOSED, 0,
-                                           sk->sk_lingertime);
-                release_sock(sk);
-        }
-
         sock_orphan(sk);
         iucv_sock_kill(sk);
         return err;
@@ -927,18 +959,52 @@ static void iucv_callback_connack(struct iucv_path *path, u8 ipuser[16])
         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;
+
+                nskb->h.raw = nskb->data;
+                nskb->nh.raw = nskb->data;
+                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 sk_buff *skb;
+        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);
+
         if (sk->sk_shutdown & RCV_SHUTDOWN)
                 return;
 
         skb = alloc_skb(msg->length, GFP_ATOMIC | GFP_DMA);
         if (!skb) {
-                iucv_message_reject(path, msg);
+                iucv_path_sever(path, NULL);
                 return;
         }
 
@@ -952,14 +1018,39 @@ static void iucv_callback_rx(struct iucv_path *path, struct iucv_message *msg)
                         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);
+        }
 
-                skb_reset_transport_header(skb);
-                skb_reset_network_header(skb);
-                skb->len = msg->length;
+        /* 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);
         }
 
-        if (sock_queue_rcv_skb(sk, skb))
-                kfree_skb(skb);
 }
 
 static void iucv_callback_txdone(struct iucv_path *path,
@@ -971,17 +1062,27 @@ static void iucv_callback_txdone(struct iucv_path *path,
         struct sk_buff *list_skb = list->next;
         unsigned long flags;
 
-        spin_lock_irqsave(&list->lock, flags);
+        if (list_skb) {
+                spin_lock_irqsave(&list->lock, flags);
+
+                do {
+                        this = list_skb;
+                        list_skb = list_skb->next;
+                } while (memcmp(&msg->tag, this->cb, 4) && list_skb);
+
+                spin_unlock_irqrestore(&list->lock, flags);
 
-        do {
-                this = list_skb;
-                list_skb = list_skb->next;
-        } while (memcmp(&msg->tag, this->cb, 4));
+                skb_unlink(this, &iucv_sk(sk)->send_skb_q);
+                kfree_skb(this);
+        }
 
-        spin_unlock_irqrestore(&list->lock, flags);
+        if (sk->sk_state == IUCV_CLOSING){
+                if (skb_queue_empty(&iucv_sk(sk)->send_skb_q)) {
+                        sk->sk_state = IUCV_CLOSED;
+                        sk->sk_state_change(sk);
+                }
+        }
 
-        skb_unlink(this, &iucv_sk(sk)->send_skb_q);
-        kfree_skb(this);
 }
 
 static void iucv_callback_connrej(struct iucv_path *path, u8 ipuser[16])