NFC: Stop sending LLCP frames when tx queues are getting too deep

When the tx pending queues and/or the socket tx queue is getting too deep,
we have to let userspace know. We won't be queueing any more frames until
the congestion is fixed.

Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

1 files changed, 17 insertions, 0 deletions

diff --git a/net/nfc/llcp/commands.c b/net/nfc/llcp/commands.c
index f0a39456f26b..df24be48d4da 100644
--- a/net/nfc/llcp/commands.c
+++ b/net/nfc/llcp/commands.c
@@ -528,6 +528,23 @@ int nfc_llcp_send_i_frame(struct nfc_llcp_sock *sock,
         if (local == NULL)
                 return -ENODEV;
 
+        /* Remote is ready but has not acknowledged our frames */
+        if((sock->remote_ready &&
+            skb_queue_len(&sock->tx_pending_queue) >= sock->rw &&
+            skb_queue_len(&sock->tx_queue) >= 2 * sock->rw)) {
+                pr_err("Pending queue is full %d frames\n",
+                       skb_queue_len(&sock->tx_pending_queue));
+                return -ENOBUFS;
+        }
+
+        /* Remote is not ready and we've been queueing enough frames */
+        if ((!sock->remote_ready &&
+             skb_queue_len(&sock->tx_queue) >= 2 * sock->rw)) {
+                pr_err("Tx queue is full %d frames\n",
+                       skb_queue_len(&sock->tx_queue));
+                return -ENOBUFS;
+        }
+
         msg_data = kzalloc(len, GFP_KERNEL);
         if (msg_data == NULL)
                 return -ENOMEM;