From: Hendrik Brueckner <brueckner@xxxxxxxxxxxxxxxxxx> AF_IUCV runs into a race when queuing 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. The race can be avoided if the message queue spinlock in the message_pending callback is spreaded across the entire callback function. Signed-off-by: Hendrik Brueckner <brueckner@xxxxxxxxxxxxxxxxxx> Signed-off-by: Ursula Braun <ursula.braun@xxxxxxxxxx> --- net/iucv/af_iucv.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) 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 @@ -1409,6 +1409,8 @@ static void iucv_callback_rx(struct iucv return; } + spin_lock(&iucv->message_q.lock); + if (!list_empty(&iucv->message_q.list) || !skb_queue_empty(&iucv->backlog_skb_q)) goto save_message; @@ -1422,9 +1424,8 @@ 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); + goto out_unlock; return; @@ -1435,8 +1436,9 @@ 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); } -- To unsubscribe from this list: send the line "unsubscribe linux-s390" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
