Re: [PATCH net-next v3 1/3] flow_dissector: factor out the ports extraction in skb_flow_get_ports

Veaceslav Falico
2013-09-26T14:38:27Z

On Thu, Sep 26, 2013 at 04:09:40PM +0200, Nikolay Aleksandrov wrote:
>Factor out the code that extracts the ports from skb_flow_dissect and
>add a new function skb_flow_get_ports which can be re-used.
>
>Suggested-by: Veaceslav Falico <vfalico@redhat.com>
>Signed-off-by: Nikolay Aleksandrov <nikolay@redhat.com>

Reviewed-by: Veaceslav Falico <vfalico@redhat.com>

>---
>v2: new patch
>v3: fix a bug in skb_flow_dissect where thoff didn't have poff added by
> modifying thoff directly in skb_flow_get_ports as it's done anyway.
> Also add the necessary export symbol for skb_flow_get_ports.
>This seems like a good idea because there're other users that can re-use
>it later as well.
>
> include/net/flow_keys.h | 1 +
> net/core/flow_dissector.c | 41 ++++++++++++++++++++++++++++++-----------
> 2 files changed, 31 insertions(+), 11 deletions(-)
>
>diff --git a/include/net/flow_keys.h b/include/net/flow_keys.h
>index ac2439d..4db84ae 100644
>--- a/include/net/flow_keys.h
>+++ b/include/net/flow_keys.h
>@@ -14,4 +14,5 @@ struct flow_keys {
> };
>
> bool skb_flow_dissect(const struct sk_buff *skb, struct flow_keys *flow);
>+__be32 skb_flow_get_ports(const struct sk_buff *skb, int *thoff, u8 ip_proto);
> #endif
>diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c
>index 1929af8..7785398 100644
>--- a/net/core/flow_dissector.c
>+++ b/net/core/flow_dissector.c
>@@ -25,9 +25,37 @@ static void iph_to_flow_copy_addrs(struct flow_keys *flow, const struct iphdr *i
> memcpy(&flow->src, &iph->saddr, sizeof(flow->src) + sizeof(flow->dst));
> }
>
>+/**
>+ * skb_flow_get_ports - extract the upper layer ports and return them
>+ * @skb: buffer to extract the ports from
>+ * @thoff: pointer to transport header offset
>+ * @ip_proto: protocol for which to get port offset
>+ *
>+ * The function will try to retrieve the ports at offset thoff + poff where poff
>+ * is the protocol port offset returned from proto_ports_offset, and if poff is
>+ * more than or equal to 0 it'll add it to the value at the thoff address
>+ */
>+__be32 skb_flow_get_ports(const struct sk_buff *skb, int *thoff, u8 ip_proto)
>+{
>+ int poff = proto_ports_offset(ip_proto);
>+
>+ if (poff >= 0) {
>+ __be32 *ports, _ports;
>+
>+ *thoff += poff;
>+ ports = skb_header_pointer(skb, *thoff, sizeof(_ports),
>+ &_ports);
>+ if (ports)
>+ return *ports;
>+ }
>+
>+ return 0;
>+}
>+EXPORT_SYMBOL(skb_flow_get_ports);
>+
> bool skb_flow_dissect(const struct sk_buff *skb, struct flow_keys *flow)
> {
>- int poff, nhoff = skb_network_offset(skb);
>+ int nhoff = skb_network_offset(skb);
> u8 ip_proto;
> __be16 proto = skb->protocol;
>
>@@ -150,16 +178,7 @@ ipv6:
> }
>
> flow->ip_proto = ip_proto;
>- poff = proto_ports_offset(ip_proto);
>- if (poff >= 0) {
>- __be32 *ports, _ports;
>-
>- nhoff += poff;
>- ports = skb_header_pointer(skb, nhoff, sizeof(_ports), &_ports);
>- if (ports)
>- flow->ports = *ports;
>- }
>-
>+ flow->ports = skb_flow_get_ports(skb, &nhoff, ip_proto);
> flow->thoff = (u16) nhoff;
>
> return true;
>--
>1.8.1.4
>