Patch "net: fec: only clear a queue's work bit if the queue was emptied" has been added to the 4.5-stable tree

This is a note to let you know that I've just added the patch titled

net: fec: only clear a queue's work bit if the queue was emptied

to the 4.5-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
net-fec-only-clear-a-queue-s-work-bit-if-the-queue-was-emptied.patch
and it can be found in the queue-4.5 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: =?UTF-8?q?Uwe=20Kleine-K=C3=B6nig?= <[email protected]>
Date: Tue, 3 May 2016 16:38:53 +0200
Subject: net: fec: only clear a queue's work bit if the queue was emptied
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From: =?UTF-8?q?Uwe=20Kleine-K=C3=B6nig?= <[email protected]>

[ Upstream commit 1c021bb717a70aaeaa4b25c91f43c2aeddd922de ]

In the receive path a queue's work bit was cleared unconditionally even if fec_enet_rx_queue only read out a part of the available packets from the hardware. This resulted in not reading any packets in the next napi turn and so packets were delayed or lost.

The obvious fix is to only clear a queue's bit when the queue was emptied.

---
 drivers/net/ethernet/freescale/fec_main.c |   10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

@@ -1566,9 +1566,15 @@ fec_enet_rx(struct net_device *ndev, int
 	struct fec_enet_private *fep = netdev_priv(ndev);
 
 	for_each_set_bit(queue_id, &fep->work_rx, FEC_ENET_MAX_RX_QS) {
-		clear_bit(queue_id, &fep->work_rx);
-		pkt_received += fec_enet_rx_queue(ndev,
+		int ret;
+
+		ret = fec_enet_rx_queue(ndev,
 					budget - pkt_received, queue_id);
+
+		if (ret < budget - pkt_received)
+			clear_bit(queue_id, &fep->work_rx);
+
+		pkt_received += ret;
 	}
 	return pkt_received;
 }

Patches currently in stable-queue which might be from [email protected] are

queue-4.5/net-fec-only-clear-a-queue-s-work-bit-if-the-queue-was-emptied.patch