From 04d5a2d5d2d079ce5966d7e67324c9c4f648c951 Mon Sep 17 00:00:00 2001 From: Parav Pandit Date: Mon, 16 Oct 2017 08:45:16 +0300 Subject: [PATCH] IB/core: Fix calculation of maximum RoCE MTU [ Upstream commit 99260132fde7bddc6e0132ce53da94d1c9ccabcb ] The original code only took into consideration the largest header possible after the IB_BTH_BYTES. This was incorrect, as the largest possible header size is the largest possible combination of headers we might run into. The new code accounts for all possible headers in the largest possible combination and subtracts that from the MTU to make sure that all packets will fit on the wire. Link: https://www.spinics.net/lists/linux-rdma/msg54558.html Fixes: 3c86aa70bf67 ("RDMA/cm: Add RDMA CM support for IBoE devices") Signed-off-by: Parav Pandit Reviewed-by: Daniel Jurgens Reported-by: Roland Dreier Signed-off-by: Leon Romanovsky Signed-off-by: Doug Ledford Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- include/rdma/ib_addr.h | 7 ++++--- include/rdma/ib_pack.h | 19 +++++++++++-------- 2 files changed, 15 insertions(+), 11 deletions(-) diff --git a/include/rdma/ib_addr.h b/include/rdma/ib_addr.h index 1beab5532035..818a38f99221 100644 --- a/include/rdma/ib_addr.h +++ b/include/rdma/ib_addr.h @@ -243,10 +243,11 @@ static inline void rdma_addr_set_dgid(struct rdma_dev_addr *dev_addr, union ib_g static inline enum ib_mtu iboe_get_mtu(int mtu) { /* - * reduce IB headers from effective IBoE MTU. 28 stands for - * atomic header which is the biggest possible header after BTH + * Reduce IB headers from effective IBoE MTU. */ - mtu = mtu - IB_GRH_BYTES - IB_BTH_BYTES - 28; + mtu = mtu - (IB_GRH_BYTES + IB_UDP_BYTES + IB_BTH_BYTES + + IB_EXT_XRC_BYTES + IB_EXT_ATOMICETH_BYTES + + IB_ICRC_BYTES); if (mtu >= ib_mtu_enum_to_int(IB_MTU_4096)) return IB_MTU_4096; diff --git a/include/rdma/ib_pack.h b/include/rdma/ib_pack.h index b13419ce99ff..e02b78a38eba 100644 --- a/include/rdma/ib_pack.h +++ b/include/rdma/ib_pack.h @@ -37,14 +37,17 @@ #include enum { - IB_LRH_BYTES = 8, - IB_ETH_BYTES = 14, - IB_VLAN_BYTES = 4, - IB_GRH_BYTES = 40, - IB_IP4_BYTES = 20, - IB_UDP_BYTES = 8, - IB_BTH_BYTES = 12, - IB_DETH_BYTES = 8 + IB_LRH_BYTES = 8, + IB_ETH_BYTES = 14, + IB_VLAN_BYTES = 4, + IB_GRH_BYTES = 40, + IB_IP4_BYTES = 20, + IB_UDP_BYTES = 8, + IB_BTH_BYTES = 12, + IB_DETH_BYTES = 8, + IB_EXT_ATOMICETH_BYTES = 28, + IB_EXT_XRC_BYTES = 4, + IB_ICRC_BYTES = 4 }; struct ib_field { -- 2.11.0