Patch "IB/mlx4: Increase maximal message size under UD QP" has been added to the 4.4-stable tree

[<gregkh@linuxfoundation.org>]

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

    IB/mlx4: Increase maximal message size under UD QP

to the 4.4-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:
     ib-mlx4-increase-maximal-message-size-under-ud-qp.patch
and it can be found in the queue-4.4 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 Tue Dec 12 13:38:50 CET 2017
From: Mark Bloch <markb@mellanox.com>
Date: Thu, 2 Nov 2017 15:22:26 +0200
Subject: IB/mlx4: Increase maximal message size under UD QP

From: Mark Bloch <markb@mellanox.com>


[ Upstream commit 5f22a1d87c5315a98981ecf93cd8de226cffe6ca ]

Maximal message should be used as a limit to the max message payload allowed,
without the headers. The ConnectX-3 check is done against this value includes
the headers. When the payload is 4K this will cause the NIC to drop packets.

Increase maximal message to 8K as workaround, this shouldn't change current
behaviour because we continue to set the MTU to 4k.

To reproduce;
set MTU to 4296 on the corresponding interface, for example:
ifconfig eth0 mtu 4296 (both server and client)

On server:
ib_send_bw -c UD -d mlx4_0 -s 4096 -n 1000000 -i1 -m 4096

On client:
ib_send_bw -d mlx4_0 -c UD <server_ip> -s 4096 -n 1000000 -i 1 -m 4096

Fixes: 6e0d733d9215 ("IB/mlx4: Allow 4K messages for UD QPs")
Signed-off-by: Mark Bloch <markb@mellanox.com>
Reviewed-by: Majd Dibbiny <majd@mellanox.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Signed-off-by: Doug Ledford <dledford@redhat.com>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/infiniband/hw/mlx4/qp.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/infiniband/hw/mlx4/qp.c
+++ b/drivers/infiniband/hw/mlx4/qp.c
@@ -1564,7 +1564,7 @@ static int __mlx4_ib_modify_qp(struct ib
 			context->mtu_msgmax = (IB_MTU_4096 << 5) |
 					      ilog2(dev->dev->caps.max_gso_sz);
 		else
-			context->mtu_msgmax = (IB_MTU_4096 << 5) | 12;
+			context->mtu_msgmax = (IB_MTU_4096 << 5) | 13;
 	} else if (attr_mask & IB_QP_PATH_MTU) {
 		if (attr->path_mtu < IB_MTU_256 || attr->path_mtu > IB_MTU_4096) {
 			pr_err("path MTU (%u) is invalid\n",


Patches currently in stable-queue which might be from markb@mellanox.com are

queue-4.4/ib-mlx4-increase-maximal-message-size-under-ud-qp.patch