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Subject[RFC net-next] net: dsa: Remove indirect function call for flow dissection
Date
We only need "static" information to be given for DSA flow dissection,
replace the call to .flow_dissect() with an unsigned integer given us
the offset into the packet that we must de-reference to obtain the
protocol number.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
---
Alexander,

This should probably require us to fix all DSA taggers to provide a
valid proto_off otherwise we would be incorrectly dissecting a flow, but
that still sounds like an improvement to me.

Thanks!

include/net/dsa.h | 3 +--
net/core/flow_dissector.c | 13 ++++++++-----
net/dsa/tag_dsa.c | 10 +---------
net/dsa/tag_edsa.c | 10 +---------
net/dsa/tag_mtk.c | 11 +----------
net/dsa/tag_qca.c | 11 +----------
6 files changed, 13 insertions(+), 45 deletions(-)

diff --git a/include/net/dsa.h b/include/net/dsa.h
index 6767dc3f66c0..8e3e1fa06d75 100644
--- a/include/net/dsa.h
+++ b/include/net/dsa.h
@@ -70,14 +70,13 @@ struct dsa_device_ops {
struct sk_buff *(*xmit)(struct sk_buff *skb, struct net_device *dev);
struct sk_buff *(*rcv)(struct sk_buff *skb, struct net_device *dev,
struct packet_type *pt);
- int (*flow_dissect)(const struct sk_buff *skb, __be16 *proto,
- int *offset);
/* Used to determine which traffic should match the DSA filter in
* eth_type_trans, and which, if any, should bypass it and be processed
* as regular on the master net device.
*/
bool (*filter)(const struct sk_buff *skb, struct net_device *dev);
unsigned int overhead;
+ unsigned int proto_off;
const char *name;
enum dsa_tag_protocol proto;
};
diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c
index d524a693e00f..9037ebdddac1 100644
--- a/net/core/flow_dissector.c
+++ b/net/core/flow_dissector.c
@@ -972,13 +972,16 @@ bool __skb_flow_dissect(const struct net *net,
if (unlikely(skb->dev && netdev_uses_dsa(skb->dev) &&
proto == htons(ETH_P_XDSA))) {
const struct dsa_device_ops *ops;
- int offset = 0;
+ unsigned int overhead;
+ unsigned int proto_off;

ops = skb->dev->dsa_ptr->tag_ops;
- if (ops->flow_dissect &&
- !ops->flow_dissect(skb, &proto, &offset)) {
- hlen -= offset;
- nhoff += offset;
+ overhead = ops->overhead;
+ proto_off = ops->proto_off;
+ if (overhead && likely(proto_off < skb->len)) {
+ hlen -= overhead;
+ nhoff += overhead;
+ proto = ((__be16 *)skb->data)[proto_off];
}
}
#endif
diff --git a/net/dsa/tag_dsa.c b/net/dsa/tag_dsa.c
index 7ddec9794477..4a970e959fef 100644
--- a/net/dsa/tag_dsa.c
+++ b/net/dsa/tag_dsa.c
@@ -142,21 +142,13 @@ static struct sk_buff *dsa_rcv(struct sk_buff *skb, struct net_device *dev,
return skb;
}

-static int dsa_tag_flow_dissect(const struct sk_buff *skb, __be16 *proto,
- int *offset)
-{
- *offset = 4;
- *proto = ((__be16 *)skb->data)[1];
- return 0;
-}
-
static const struct dsa_device_ops dsa_netdev_ops = {
.name = "dsa",
.proto = DSA_TAG_PROTO_DSA,
.xmit = dsa_xmit,
.rcv = dsa_rcv,
- .flow_dissect = dsa_tag_flow_dissect,
.overhead = DSA_HLEN,
+ .proto_off = 1,
};

MODULE_LICENSE("GPL");
diff --git a/net/dsa/tag_edsa.c b/net/dsa/tag_edsa.c
index e8eaa804ccb9..c7cb0df17287 100644
--- a/net/dsa/tag_edsa.c
+++ b/net/dsa/tag_edsa.c
@@ -161,21 +161,13 @@ static struct sk_buff *edsa_rcv(struct sk_buff *skb, struct net_device *dev,
return skb;
}

-static int edsa_tag_flow_dissect(const struct sk_buff *skb, __be16 *proto,
- int *offset)
-{
- *offset = 8;
- *proto = ((__be16 *)skb->data)[3];
- return 0;
-}
-
static const struct dsa_device_ops edsa_netdev_ops = {
.name = "edsa",
.proto = DSA_TAG_PROTO_EDSA,
.xmit = edsa_xmit,
.rcv = edsa_rcv,
- .flow_dissect = edsa_tag_flow_dissect,
.overhead = EDSA_HLEN,
+ .proto_off = 3,
};

MODULE_LICENSE("GPL");
diff --git a/net/dsa/tag_mtk.c b/net/dsa/tag_mtk.c
index b5705cba8318..c96354f12317 100644
--- a/net/dsa/tag_mtk.c
+++ b/net/dsa/tag_mtk.c
@@ -89,22 +89,13 @@ static struct sk_buff *mtk_tag_rcv(struct sk_buff *skb, struct net_device *dev,
return skb;
}

-static int mtk_tag_flow_dissect(const struct sk_buff *skb, __be16 *proto,
- int *offset)
-{
- *offset = 4;
- *proto = ((__be16 *)skb->data)[1];
-
- return 0;
-}
-
static const struct dsa_device_ops mtk_netdev_ops = {
.name = "mtk",
.proto = DSA_TAG_PROTO_MTK,
.xmit = mtk_tag_xmit,
.rcv = mtk_tag_rcv,
- .flow_dissect = mtk_tag_flow_dissect,
.overhead = MTK_HDR_LEN,
+ .proto_off = 1,
};

MODULE_LICENSE("GPL");
diff --git a/net/dsa/tag_qca.c b/net/dsa/tag_qca.c
index c95885215525..a88849d211f0 100644
--- a/net/dsa/tag_qca.c
+++ b/net/dsa/tag_qca.c
@@ -90,22 +90,13 @@ static struct sk_buff *qca_tag_rcv(struct sk_buff *skb, struct net_device *dev,
return skb;
}

-static int qca_tag_flow_dissect(const struct sk_buff *skb, __be16 *proto,
- int *offset)
-{
- *offset = QCA_HDR_LEN;
- *proto = ((__be16 *)skb->data)[0];
-
- return 0;
-}
-
static const struct dsa_device_ops qca_netdev_ops = {
.name = "qca",
.proto = DSA_TAG_PROTO_QCA,
.xmit = qca_tag_xmit,
.rcv = qca_tag_rcv,
- .flow_dissect = qca_tag_flow_dissect,
.overhead = QCA_HDR_LEN,
+ .proto_offset = 0,
};

MODULE_LICENSE("GPL");
--
2.17.1
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