Move xen patchset to new version's subdir.

[people/pmueller/ipfire-2.x.git] / src / patches / suse-2.6.27.31 / patches.arch / s390-13-01-af_iucv-fix-race-msgpending.patch

From: Gerald Schaefer <geraldsc@de.ibm.com>
Subject: af_iucv: Fix race when queuing incoming iucv messages
References: bnc#499845,LTC#53033

Symptom:     A socket application does not receive any new data even
             if incoming IUCV messages are received and queued.
Problem:     AF_IUCV runs into a race when queueing incoming iucv
             messages and receiving the resulting backlog.
             If the Linux system is under pressure (high load or
             steal time), the message queue grows up, but messages
             are not received and queued onto the backlog queue.
             In that case, applications do not receive any data with
             recvmsg() even if AF_IUCV puts incoming messages onto
             the message queue.
Solution:    The race can be avoided if the message queue
             spinlock in the message_pending callback is
             spreaded across the entire callback function.

Acked-by: John Jolly <jjolly@suse.de>
---
 net/iucv/af_iucv.c |   10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

--- a/net/iucv/af_iucv.c
+++ b/net/iucv/af_iucv.c
@@ -1089,6 +1089,8 @@ static void iucv_callback_rx(struct iucv
 	if (sk->sk_shutdown & RCV_SHUTDOWN)
 		return;
 
+	spin_lock(&iucv->message_q.lock);
+
 	if (!list_empty(&iucv->message_q.list) ||
 	    !skb_queue_empty(&iucv->backlog_skb_q))
 		goto save_message;
@@ -1102,11 +1104,8 @@ static void iucv_callback_rx(struct iucv
 	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;
+	goto out_unlock;
 
 save_message:
 	save_msg = kzalloc(sizeof(struct sock_msg_q), GFP_ATOMIC | GFP_DMA);
@@ -1115,8 +1114,9 @@ save_message:
 	save_msg->path = path;
 	save_msg->msg = *msg;
 
-	spin_lock(&iucv->message_q.lock);
 	list_add_tail(&save_msg->list, &iucv->message_q.list);
+
+out_unlock:
 	spin_unlock(&iucv->message_q.lock);
 }