nfp: flower: split and limit cmsg skb lists

Introduce a second skb list for handling control messages and limit the
number of allowed messages. Some control messages are considered more
crucial than others, resulting in the need for a second skb list. By
splitting the list into a separate high and low priority list we can
ensure that messages on the high list get added to the head of the list
that gets processed, this however has no functional impact. Previously
there was no limit on the number of messages allowed on the queue, this
could result in the queue growing boundlessly and eventually the host
running out of memory.

Fixes: b985f870a5f0 ("nfp: process control messages in workqueue in flower app")
Signed-off-by: Pieter Jansen van Vuuren <pieter.jansenvanvuuren@netronome.com>
Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Simon Horman <simon.horman@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 34 insertions, 4 deletions

diff --git a/drivers/net/ethernet/netronome/nfp/flower/cmsg.c b/drivers/net/ethernet/netronome/nfp/flower/cmsg.c
index 8ad857eb89c6..577659f332e4 100644
--- a/drivers/net/ethernet/netronome/nfp/flower/cmsg.c
+++ b/drivers/net/ethernet/netronome/nfp/flower/cmsg.c
@@ -272,18 +272,49 @@ out:
 
 void nfp_flower_cmsg_process_rx(struct work_struct *work)
 {
+	struct sk_buff_head cmsg_joined;
 	struct nfp_flower_priv *priv;
 	struct sk_buff *skb;
 
 	priv = container_of(work, struct nfp_flower_priv, cmsg_work);
+	skb_queue_head_init(&cmsg_joined);
 
-	while ((skb = skb_dequeue(&priv->cmsg_skbs)))
+	spin_lock_bh(&priv->cmsg_skbs_high.lock);
+	skb_queue_splice_tail_init(&priv->cmsg_skbs_high, &cmsg_joined);
+	spin_unlock_bh(&priv->cmsg_skbs_high.lock);
+
+	spin_lock_bh(&priv->cmsg_skbs_low.lock);
+	skb_queue_splice_tail_init(&priv->cmsg_skbs_low, &cmsg_joined);
+	spin_unlock_bh(&priv->cmsg_skbs_low.lock);
+
+	while ((skb = __skb_dequeue(&cmsg_joined)))
 		nfp_flower_cmsg_process_one_rx(priv->app, skb);
 }
 
-void nfp_flower_cmsg_rx(struct nfp_app *app, struct sk_buff *skb)
+static void
+nfp_flower_queue_ctl_msg(struct nfp_app *app, struct sk_buff *skb, int type)
 {
 	struct nfp_flower_priv *priv = app->priv;
+	struct sk_buff_head *skb_head;
+
+	if (type == NFP_FLOWER_CMSG_TYPE_PORT_REIFY ||
+	    type == NFP_FLOWER_CMSG_TYPE_PORT_MOD)
+		skb_head = &priv->cmsg_skbs_high;
+	else
+		skb_head = &priv->cmsg_skbs_low;
+
+	if (skb_queue_len(skb_head) >= NFP_FLOWER_WORKQ_MAX_SKBS) {
+		nfp_flower_cmsg_warn(app, "Dropping queued control messages\n");
+		dev_kfree_skb_any(skb);
+		return;
+	}
+
+	skb_queue_tail(skb_head, skb);
+	schedule_work(&priv->cmsg_work);
+}
+
+void nfp_flower_cmsg_rx(struct nfp_app *app, struct sk_buff *skb)
+{
 	struct nfp_flower_cmsg_hdr *cmsg_hdr;
 
 	cmsg_hdr = nfp_flower_cmsg_get_hdr(skb);
@@ -307,7 +338,6 @@ void nfp_flower_cmsg_rx(struct nfp_app *app, struct sk_buff *skb)
 		/* Acks from the NFP that the route is added - ignore. */
 		dev_consume_skb_any(skb);
 	} else {
-		skb_queue_tail(&priv->cmsg_skbs, skb);
-		schedule_work(&priv->cmsg_work);
+		nfp_flower_queue_ctl_msg(app, skb, cmsg_hdr->type);
 	}
 }