2019-10-21 20:11:07

by Matteo Croce

Subject: [PATCH net-next 1/4] flow_dissector: add meaningful comments

Documents two piece of code which can't be understood at a glance.

Signed-off-by: Matteo Croce <[email protected]>
---
include/net/flow_dissector.h | 1 +
net/core/flow_dissector.c | 6 ++++++
2 files changed, 7 insertions(+)

diff --git a/include/net/flow_dissector.h b/include/net/flow_dissector.h
index 90bd210be060..7747af3cc500 100644
--- a/include/net/flow_dissector.h
+++ b/include/net/flow_dissector.h
@@ -282,6 +282,7 @@ struct flow_keys {
struct flow_dissector_key_vlan cvlan;
struct flow_dissector_key_keyid keyid;
struct flow_dissector_key_ports ports;
+ /* 'addrs' must be the last member */
struct flow_dissector_key_addrs addrs;
};

diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c
index 7c09d87d3269..affde70dad47 100644
--- a/net/core/flow_dissector.c
+++ b/net/core/flow_dissector.c
@@ -1374,6 +1374,9 @@ static inline size_t flow_keys_hash_length(const struct flow_keys *flow)
{
size_t diff = FLOW_KEYS_HASH_OFFSET + sizeof(flow->addrs);
BUILD_BUG_ON((sizeof(*flow) - FLOW_KEYS_HASH_OFFSET) % sizeof(u32));
+ /* flow.addrs MUST be the last member in struct flow_keys because
+ * different L3 protocols have different address length
+ */
BUILD_BUG_ON(offsetof(typeof(*flow), addrs) !=
sizeof(*flow) - sizeof(flow->addrs));

@@ -1421,6 +1424,9 @@ __be32 flow_get_u32_dst(const struct flow_keys *flow)
}
EXPORT_SYMBOL(flow_get_u32_dst);

+/* Sort the source and destination IP (and the ports if the IP are the same),
+ * to have consistent hash within the two directions
+ */
static inline void __flow_hash_consistentify(struct flow_keys *keys)
{
int addr_diff, i;
--
2.21.0

2019-10-23 12:45:04

by Simon Horman

Subject: Re: [PATCH net-next 1/4] flow_dissector: add meaningful comments

On Mon, Oct 21, 2019 at 10:09:45PM +0200, Matteo Croce wrote:
> Documents two piece of code which can't be understood at a glance.
>
> Signed-off-by: Matteo Croce <[email protected]>

Reviewed-by: Simon Horman <[email protected]>

> ---
> include/net/flow_dissector.h | 1 +
> net/core/flow_dissector.c | 6 ++++++
> 2 files changed, 7 insertions(+)
>
> diff --git a/include/net/flow_dissector.h b/include/net/flow_dissector.h
> index 90bd210be060..7747af3cc500 100644
> --- a/include/net/flow_dissector.h
> +++ b/include/net/flow_dissector.h
> @@ -282,6 +282,7 @@ struct flow_keys {
> struct flow_dissector_key_vlan cvlan;
> struct flow_dissector_key_keyid keyid;
> struct flow_dissector_key_ports ports;
> + /* 'addrs' must be the last member */
> struct flow_dissector_key_addrs addrs;
> };
>
> diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c
> index 7c09d87d3269..affde70dad47 100644
> --- a/net/core/flow_dissector.c
> +++ b/net/core/flow_dissector.c
> @@ -1374,6 +1374,9 @@ static inline size_t flow_keys_hash_length(const struct flow_keys *flow)
> {
> size_t diff = FLOW_KEYS_HASH_OFFSET + sizeof(flow->addrs);
> BUILD_BUG_ON((sizeof(*flow) - FLOW_KEYS_HASH_OFFSET) % sizeof(u32));
> + /* flow.addrs MUST be the last member in struct flow_keys because
> + * different L3 protocols have different address length
> + */
> BUILD_BUG_ON(offsetof(typeof(*flow), addrs) !=
> sizeof(*flow) - sizeof(flow->addrs));
>
> @@ -1421,6 +1424,9 @@ __be32 flow_get_u32_dst(const struct flow_keys *flow)
> }
> EXPORT_SYMBOL(flow_get_u32_dst);
>
> +/* Sort the source and destination IP (and the ports if the IP are the same),
> + * to have consistent hash within the two directions
> + */
> static inline void __flow_hash_consistentify(struct flow_keys *keys)
> {
> int addr_diff, i;
> --
> 2.21.0
>