Merge branch 'sctp-skb-list'

David Miller says:

====================
SCTP: Event skb list overhaul.

This patch series eliminates the explicit reference to the skb list
implementation via skb->prev dereferences.

The approach used is to pass a non-empty skb list around instead of an
event skb object which may or may not be on a list.

I'd like to thank Marcelo Leitner, Xin Long, and Neil Horman for
reviewing previous versions of this series.

Testing would be very much appreciated, in addition to the review of
course.

v4 --> v5: Rebase to net-next

v3 --> v4: Fix the logic in patch #4 so that we don't miss cases
           where we should add event to the on-stack temp list.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 24 insertions, 26 deletions

diff --git a/net/sctp/ulpqueue.c b/net/sctp/ulpqueue.c
index 5dde92101743..7cdc3623fa35 100644
--- a/net/sctp/ulpqueue.c
+++ b/net/sctp/ulpqueue.c
@@ -116,12 +116,13 @@ int sctp_ulpq_tail_data(struct sctp_ulpq *ulpq, struct sctp_chunk *chunk,
 	event = sctp_ulpq_reasm(ulpq, event);
 
 	/* Do ordering if needed.  */
-	if ((event) && (event->msg_flags & MSG_EOR)) {
+	if (event) {
 		/* Create a temporary list to collect chunks on.  */
 		skb_queue_head_init(&temp);
 		__skb_queue_tail(&temp, sctp_event2skb(event));
 
-		event = sctp_ulpq_order(ulpq, event);
+		if (event->msg_flags & MSG_EOR)
+			event = sctp_ulpq_order(ulpq, event);
 	}
 
 	/* Send event to the ULP.  'event' is the sctp_ulpevent for
@@ -129,7 +130,7 @@ int sctp_ulpq_tail_data(struct sctp_ulpq *ulpq, struct sctp_chunk *chunk,
 	 */
 	if (event) {
 		event_eor = (event->msg_flags & MSG_EOR) ? 1 : 0;
-		sctp_ulpq_tail_event(ulpq, event);
+		sctp_ulpq_tail_event(ulpq, &temp);
 	}
 
 	return event_eor;
@@ -193,18 +194,17 @@ static int sctp_ulpq_clear_pd(struct sctp_ulpq *ulpq)
 	return sctp_clear_pd(ulpq->asoc->base.sk, ulpq->asoc);
 }
 
-/* If the SKB of 'event' is on a list, it is the first such member
- * of that list.
- */
-int sctp_ulpq_tail_event(struct sctp_ulpq *ulpq, struct sctp_ulpevent *event)
+int sctp_ulpq_tail_event(struct sctp_ulpq *ulpq, struct sk_buff_head *skb_list)
 {
 	struct sock *sk = ulpq->asoc->base.sk;
 	struct sctp_sock *sp = sctp_sk(sk);
-	struct sk_buff_head *queue, *skb_list;
-	struct sk_buff *skb = sctp_event2skb(event);
+	struct sctp_ulpevent *event;
+	struct sk_buff_head *queue;
+	struct sk_buff *skb;
 	int clear_pd = 0;
 
-	skb_list = (struct sk_buff_head *) skb->prev;
+	skb = __skb_peek(skb_list);
+	event = sctp_skb2event(skb);
 
 	/* If the socket is just going to throw this away, do not
 	 * even try to deliver it.
@@ -257,13 +257,7 @@ int sctp_ulpq_tail_event(struct sctp_ulpq *ulpq, struct sctp_ulpevent *event)
 		}
 	}
 
-	/* If we are harvesting multiple skbs they will be
-	 * collected on a list.
-	 */
-	if (skb_list)
-		skb_queue_splice_tail_init(skb_list, queue);
-	else
-		__skb_queue_tail(queue, skb);
+	skb_queue_splice_tail_init(skb_list, queue);
 
 	/* Did we just complete partial delivery and need to get
 	 * rolling again?  Move pending data to the receive
@@ -738,25 +732,25 @@ void sctp_ulpq_reasm_flushtsn(struct sctp_ulpq *ulpq, __u32 fwd_tsn)
 static void sctp_ulpq_reasm_drain(struct sctp_ulpq *ulpq)
 {
 	struct sctp_ulpevent *event = NULL;
-	struct sk_buff_head temp;
 
 	if (skb_queue_empty(&ulpq->reasm))
 		return;
 
 	while ((event = sctp_ulpq_retrieve_reassembled(ulpq)) != NULL) {
-		/* Do ordering if needed.  */
-		if ((event) && (event->msg_flags & MSG_EOR)) {
-			skb_queue_head_init(&temp);
-			__skb_queue_tail(&temp, sctp_event2skb(event));
+		struct sk_buff_head temp;
+
+		skb_queue_head_init(&temp);
+		__skb_queue_tail(&temp, sctp_event2skb(event));
 
+		/* Do ordering if needed.  */
+		if (event->msg_flags & MSG_EOR)
 			event = sctp_ulpq_order(ulpq, event);
-		}
 
 		/* Send event to the ULP.  'event' is the
 		 * sctp_ulpevent for  very first SKB on the  temp' list.
 		 */
 		if (event)
-			sctp_ulpq_tail_event(ulpq, event);
+			sctp_ulpq_tail_event(ulpq, &temp);
 	}
 }
 
@@ -956,7 +950,7 @@ static void sctp_ulpq_reap_ordered(struct sctp_ulpq *ulpq, __u16 sid)
 	if (event) {
 		/* see if we have more ordered that we can deliver */
 		sctp_ulpq_retrieve_ordered(ulpq, event);
-		sctp_ulpq_tail_event(ulpq, event);
+		sctp_ulpq_tail_event(ulpq, &temp);
 	}
 }
 
@@ -1082,7 +1076,11 @@ void sctp_ulpq_partial_delivery(struct sctp_ulpq *ulpq,
 		event = sctp_ulpq_retrieve_first(ulpq);
 		/* Send event to the ULP.   */
 		if (event) {
-			sctp_ulpq_tail_event(ulpq, event);
+			struct sk_buff_head temp;
+
+			skb_queue_head_init(&temp);
+			__skb_queue_tail(&temp, sctp_event2skb(event));
+			sctp_ulpq_tail_event(ulpq, &temp);
 			sctp_ulpq_set_pd(ulpq);
 			return;
 		}