From: Vladimir Oltean <vladimir.oltean@nxp.com>
To: netdev@vger.kernel.org, davem@davemloft.net
Cc: andrew@lunn.ch, f.fainelli@gmail.com, vivien.didelot@gmail.com,
kuba@kernel.org
Subject: [PATCH v3 net-next 08/15] net: flow_dissector: avoid indirect call to DSA .flow_dissect for generic case
Date: Sat, 26 Sep 2020 22:32:08 +0300 [thread overview]
Message-ID: <20200926193215.1405730-9-vladimir.oltean@nxp.com> (raw)
In-Reply-To: <20200926193215.1405730-1-vladimir.oltean@nxp.com>
With the recent mitigations against speculative execution exploits,
indirect function calls are more expensive and it would be good to avoid
them where possible.
In the case of DSA, most switch taggers will shift the EtherType and
next headers by a fixed amount equal to that tag's length in bytes.
So we can use a generic procedure to determine that, without calling
into custom tagger code. However we still leave the flow_dissect method
inside struct dsa_device_ops as an override for the generic function.
Suggested-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
---
Changes in v3:
Patch is new.
net/core/flow_dissector.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c
index 13cc4c0a8863..e21950a2c897 100644
--- a/net/core/flow_dissector.c
+++ b/net/core/flow_dissector.c
@@ -932,8 +932,14 @@ bool __skb_flow_dissect(const struct net *net,
int offset = 0;
ops = skb->dev->dsa_ptr->tag_ops;
- if (ops->flow_dissect) {
- ops->flow_dissect(skb, &proto, &offset);
+ /* Tail taggers don't break flow dissection */
+ if (!ops->tail_tag) {
+ if (ops->flow_dissect)
+ ops->flow_dissect(skb, &proto, &offset);
+ else
+ dsa_tag_generic_flow_dissect(skb,
+ &proto,
+ &offset);
hlen -= offset;
nhoff += offset;
}
--
2.25.1
next prev parent reply other threads:[~2020-09-26 19:33 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-26 19:32 [PATCH v3 net-next 00/15] Generic adjustment for flow dissector in DSA Vladimir Oltean
2020-09-26 19:32 ` [PATCH v3 net-next 01/15] net: mscc: ocelot: move NPI port configuration to DSA Vladimir Oltean
2020-09-26 19:32 ` [PATCH v3 net-next 02/15] net: dsa: allow drivers to request promiscuous mode on master Vladimir Oltean
2020-09-26 20:22 ` Andrew Lunn
2020-09-26 19:32 ` [PATCH v3 net-next 03/15] net: dsa: tag_sja1105: request promiscuous mode for master Vladimir Oltean
2020-09-26 20:22 ` Andrew Lunn
2020-09-26 19:32 ` [PATCH v3 net-next 04/15] net: dsa: tag_ocelot: use a short prefix on both ingress and egress Vladimir Oltean
2020-09-26 19:32 ` [PATCH v3 net-next 05/15] net: dsa: make the .flow_dissect tagger callback return void Vladimir Oltean
2020-09-26 19:32 ` [PATCH v3 net-next 06/15] net: dsa: add a generic procedure for the flow dissector Vladimir Oltean
2020-09-26 20:25 ` Andrew Lunn
2020-09-26 20:33 ` Andrew Lunn
2020-09-26 20:49 ` Vladimir Oltean
2020-09-26 19:32 ` [PATCH v3 net-next 07/15] net: dsa: point out the tail taggers Vladimir Oltean
2020-09-26 20:27 ` Andrew Lunn
2020-09-26 19:32 ` Vladimir Oltean [this message]
2020-09-26 19:32 ` [PATCH v3 net-next 09/15] net: dsa: tag_brcm: use generic flow dissector procedure Vladimir Oltean
2020-09-26 19:32 ` [PATCH v3 net-next 10/15] net: dsa: tag_dsa: use the " Vladimir Oltean
2020-09-26 21:08 ` Andrew Lunn
2020-09-26 19:32 ` [PATCH v3 net-next 11/15] net: dsa: tag_edsa: " Vladimir Oltean
2020-09-26 21:08 ` Andrew Lunn
2020-09-26 19:32 ` [PATCH v3 net-next 12/15] net: dsa: tag_mtk: " Vladimir Oltean
2020-09-26 19:32 ` [PATCH v3 net-next 13/15] net: dsa: tag_qca: " Vladimir Oltean
2020-09-26 19:32 ` [PATCH v3 net-next 14/15] net: dsa: tag_sja1105: use a custom " Vladimir Oltean
2020-09-26 19:32 ` [PATCH v3 net-next 15/15] net: dsa: tag_rtl4_a: use the generic " Vladimir Oltean
2020-09-30 8:36 ` Linus Walleij
2020-09-26 21:18 ` [PATCH v3 net-next 00/15] Generic adjustment for flow dissector in DSA David Miller
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