From: Parav Pandit parav@mellanox.com
[ 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 parav@mellanox.com Reviewed-by: Daniel Jurgens danielj@mellanox.com Reported-by: Roland Dreier roland@purestorage.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 --- 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 ec5008cf5d51..8815989301ab 100644 --- a/include/rdma/ib_addr.h +++ b/include/rdma/ib_addr.h @@ -245,10 +245,11 @@ 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 36655899ee02..7ea1382ad0e5 100644 --- a/include/rdma/ib_pack.h +++ b/include/rdma/ib_pack.h @@ -37,14 +37,17 @@ #include <uapi/linux/if_ether.h>
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 {