Patch "net/mlx4_en: fix spurious timestamping callbacks" has been added to the 4.5-stable tree

Patch "net/mlx4_en: fix spurious timestamping callbacks" has been added to the 4.5-stable tree

[gregkh]

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

    net/mlx4_en: fix spurious timestamping callbacks

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-mlx4_en-fix-spurious-timestamping-callbacks.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 <stable@vger.kernel.org> know about it.


>From foo@baz Mon May 16 11:20:33 PDT 2016
From: Eric Dumazet <edumazet@google.com>
Date: Sat, 23 Apr 2016 11:35:46 -0700
Subject: net/mlx4_en: fix spurious timestamping callbacks

From: Eric Dumazet <edumazet@google.com>

[ Upstream commit fc96256c906362e845d848d0f6a6354450059e81 ]

When multiple skb are TX-completed in a row, we might incorrectly keep
a timestamp of a prior skb and cause extra work.

Fixes: ec693d47010e8 ("net/mlx4_en: Add HW timestamping (TS) support")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Willem de Bruijn <willemb@google.com>
Reviewed-by: Eran Ben Elisha <eranbe@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/net/ethernet/mellanox/mlx4/en_tx.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

--- a/drivers/net/ethernet/mellanox/mlx4/en_tx.c
+++ b/drivers/net/ethernet/mellanox/mlx4/en_tx.c
@@ -402,7 +402,6 @@ static bool mlx4_en_process_tx_cq(struct
 	u32 packets = 0;
 	u32 bytes = 0;
 	int factor = priv->cqe_factor;
-	u64 timestamp = 0;
 	int done = 0;
 	int budget = priv->tx_work_limit;
 	u32 last_nr_txbb;
@@ -442,9 +441,12 @@ static bool mlx4_en_process_tx_cq(struct
 		new_index = be16_to_cpu(cqe->wqe_index) & size_mask;
 
 		do {
+			u64 timestamp = 0;
+
 			txbbs_skipped += last_nr_txbb;
 			ring_index = (ring_index + last_nr_txbb) & size_mask;
-			if (ring->tx_info[ring_index].ts_requested)
+
+			if (unlikely(ring->tx_info[ring_index].ts_requested))
 				timestamp = mlx4_en_get_cqe_ts(cqe);
 
 			/* free next descriptor */


Patches currently in stable-queue which might be from edumazet@google.com are

queue-4.5/tcp-refresh-skb-timestamp-at-retransmit-time.patch
queue-4.5/netem-segment-gso-packets-on-enqueue.patch
queue-4.5/net-mlx4_en-fix-spurious-timestamping-callbacks.patch
queue-4.5/net-sched-do-not-requeue-a-null-skb.patch
queue-4.5/soreuseport-fix-ordering-for-mixed-v4-v6-sockets.patch