From: Julian Wiedmann <jwi@linux.ibm.com>
Subject: s390/qeth: clean up initial MTU determination
Patch-mainline: v4.15-rc1
Git-commit: 6e6f472d92bd4ccd88a9a12e55b484ab417c168c
References: FATE#326350, LTC#169511, bsc#1113509
Summary: qeth: performance improvements
Description: This adds recent functional and performance improvements for the
qeth network driver.
Primarily this brings Scatter-Gather support for HiperSockets,
reduced CPU consumption in the L3 IPv4 transmit path for OSA,
improved Promiscuous Mode performance due to IFF_UNICAST_FLT,
support for Scatter-Gather on z/VM virtual NICs, and
support for delayed GRO flushing.
For sanity & stability reasons, this effectively constitutes a
backport of the qeth device driver from 4.19 mainline.
Upstream-Description:
s390/qeth: clean up initial MTU determination
1. Drop the support for Token Ring,
2. use the ETH_DATA_LEN macro for the default L2 MTU,
3. handle OSM via the default case (as OSM is L2-only), and
4. document why the L3 MTU is reduced.
Signed-off-by: Julian Wiedmann <jwi@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Acked-by: Petr Tesarik <ptesarik@suse.com>
---
drivers/s390/net/qeth_core_main.c | 14 ++++----------
1 file changed, 4 insertions(+), 10 deletions(-)
--- a/drivers/s390/net/qeth_core_main.c
+++ b/drivers/s390/net/qeth_core_main.c
@@ -2243,18 +2243,12 @@ static int qeth_get_initial_mtu_for_card
case QETH_CARD_TYPE_IQD:
return card->info.max_mtu;
case QETH_CARD_TYPE_OSD:
- switch (card->info.link_type) {
- case QETH_LINK_TYPE_HSTR:
- case QETH_LINK_TYPE_LANE_TR:
- return 2000;
- default:
- return card->options.layer2 ? 1500 : 1492;
- }
- case QETH_CARD_TYPE_OSM:
case QETH_CARD_TYPE_OSX:
- return card->options.layer2 ? 1500 : 1492;
+ if (!card->options.layer2)
+ return ETH_DATA_LEN - 8; /* L3: allow for LLC + SNAP */
+ /* fall through */
default:
- return 1500;
+ return ETH_DATA_LEN;
}
}