From c09eb9352978fc0344e1865a1857e6e1c9cf266f Mon Sep 17 00:00:00 2001 From: Hyong Youb Kim Date: Thu, 14 Mar 2019 04:05:32 -0700 Subject: [PATCH] net/enic: fix max MTU calculation The maximum packet length (max_pkt_len) from the firmware does not include CRC, so do not subtract 4 when deriving the max MTU. This change effectively increases the max MTU by 4B. Apps often assume max MTU = max_rx_pkt_len - 14 (ethernet header), and attempt to set the MTU to that value (i.e. set MTU to max HW value). This change incidentally allows such apps to change MTU to max value successfully. Fixes: bb34ffb848a0 ("net/enic: determine max egress packet size and max MTU") Cc: stable@dpdk.org Signed-off-by: Hyong Youb Kim Reviewed-by: John Daley --- drivers/net/enic/enic.h | 4 ++-- drivers/net/enic/enic_res.c | 5 ++--- 2 files changed, 4 insertions(+), 5 deletions(-) diff --git a/drivers/net/enic/enic.h b/drivers/net/enic/enic.h index fa4d5590e4..9193fb0381 100644 --- a/drivers/net/enic/enic.h +++ b/drivers/net/enic/enic.h @@ -203,8 +203,8 @@ struct enic { /* Compute ethdev's max packet size from MTU */ static inline uint32_t enic_mtu_to_max_rx_pktlen(uint32_t mtu) { - /* ethdev max size includes eth and crc whereas NIC MTU does not */ - return mtu + ETHER_HDR_LEN + ETHER_CRC_LEN; + /* ethdev max size includes eth whereas NIC MTU does not */ + return mtu + ETHER_HDR_LEN; } /* Get the CQ index from a Start of Packet(SOP) RQ index */ diff --git a/drivers/net/enic/enic_res.c b/drivers/net/enic/enic_res.c index d289f3da81..f7cbc90fb6 100644 --- a/drivers/net/enic/enic_res.c +++ b/drivers/net/enic/enic_res.c @@ -61,10 +61,9 @@ int enic_get_vnic_config(struct enic *enic) * and will be 0 for legacy firmware and VICs */ if (c->max_pkt_size > ENIC_DEFAULT_RX_MAX_PKT_SIZE) - enic->max_mtu = c->max_pkt_size - (ETHER_HDR_LEN + 4); + enic->max_mtu = c->max_pkt_size - ETHER_HDR_LEN; else - enic->max_mtu = ENIC_DEFAULT_RX_MAX_PKT_SIZE - - (ETHER_HDR_LEN + 4); + enic->max_mtu = ENIC_DEFAULT_RX_MAX_PKT_SIZE - ETHER_HDR_LEN; if (c->mtu == 0) c->mtu = 1500; -- 2.20.1