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Date: Wed, 26 Jun 2024 12:51:19 +0200
From: Ilya Maximets <i.maximets@....org>
To: Adrian Moreno <amorenoz@...hat.com>, netdev@...r.kernel.org
Cc: i.maximets@....org, aconole@...hat.com, echaudro@...hat.com,
horms@...nel.org, dev@...nvswitch.org, "David S. Miller"
<davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>,
Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
Donald Hunter <donald.hunter@...il.com>, Pravin B Shelar <pshelar@....org>,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next v5 05/10] net: openvswitch: add emit_sample
action
On 6/25/24 22:51, Adrian Moreno wrote:
> Add support for a new action: emit_sample.
>
> This action accepts a u32 group id and a variable-length cookie and uses
> the psample multicast group to make the packet available for
> observability.
>
> The maximum length of the user-defined cookie is set to 16, same as
> tc_cookie, to discourage using cookies that will not be offloadable.
>
> Signed-off-by: Adrian Moreno <amorenoz@...hat.com>
> ---
> Documentation/netlink/specs/ovs_flow.yaml | 17 +++++++++
> include/uapi/linux/openvswitch.h | 28 ++++++++++++++
> net/openvswitch/Kconfig | 1 +
> net/openvswitch/actions.c | 45 +++++++++++++++++++++++
> net/openvswitch/flow_netlink.c | 33 ++++++++++++++++-
> 5 files changed, 123 insertions(+), 1 deletion(-)
>
> diff --git a/Documentation/netlink/specs/ovs_flow.yaml b/Documentation/netlink/specs/ovs_flow.yaml
> index 4fdfc6b5cae9..a7ab5593a24f 100644
> --- a/Documentation/netlink/specs/ovs_flow.yaml
> +++ b/Documentation/netlink/specs/ovs_flow.yaml
> @@ -727,6 +727,12 @@ attribute-sets:
> name: dec-ttl
> type: nest
> nested-attributes: dec-ttl-attrs
> + -
> + name: emit-sample
> + type: nest
> + nested-attributes: emit-sample-attrs
> + doc: |
> + Sends a packet sample to psample for external observation.
> -
> name: tunnel-key-attrs
> enum-name: ovs-tunnel-key-attr
> @@ -938,6 +944,17 @@ attribute-sets:
> -
> name: gbp
> type: u32
> + -
> + name: emit-sample-attrs
> + enum-name: ovs-emit-sample-attr
> + name-prefix: ovs-emit-sample-attr-
> + attributes:
> + -
> + name: group
> + type: u32
> + -
> + name: cookie
> + type: binary
>
> operations:
> name-prefix: ovs-flow-cmd-
> diff --git a/include/uapi/linux/openvswitch.h b/include/uapi/linux/openvswitch.h
> index efc82c318fa2..8cfa1b3f6b06 100644
> --- a/include/uapi/linux/openvswitch.h
> +++ b/include/uapi/linux/openvswitch.h
> @@ -914,6 +914,31 @@ struct check_pkt_len_arg {
> };
> #endif
>
> +#define OVS_EMIT_SAMPLE_COOKIE_MAX_SIZE 16
> +/**
> + * enum ovs_emit_sample_attr - Attributes for %OVS_ACTION_ATTR_EMIT_SAMPLE
> + * action.
> + *
> + * @OVS_EMIT_SAMPLE_ATTR_GROUP: 32-bit number to identify the source of the
> + * sample.
> + * @OVS_EMIT_SAMPLE_ATTR_COOKIE: A variable-length binary cookie that contains
> + * user-defined metadata. The maximum length is OVS_EMIT_SAMPLE_COOKIE_MAX_SIZE
> + * bytes.
> + *
> + * Sends the packet to the psample multicast group with the specified group and
> + * cookie. It is possible to combine this action with the
> + * %OVS_ACTION_ATTR_TRUNC action to limit the size of the packet being emitted.
> + */
> +enum ovs_emit_sample_attr {
> + OVS_EMIT_SAMPLE_ATTR_GROUP = 1, /* u32 number. */
> + OVS_EMIT_SAMPLE_ATTR_COOKIE, /* Optional, user specified cookie. */
> +
> + /* private: */
> + __OVS_EMIT_SAMPLE_ATTR_MAX
> +};
> +
> +#define OVS_EMIT_SAMPLE_ATTR_MAX (__OVS_EMIT_SAMPLE_ATTR_MAX - 1)
> +
> /**
> * enum ovs_action_attr - Action types.
> *
> @@ -966,6 +991,8 @@ struct check_pkt_len_arg {
> * of l3 tunnel flag in the tun_flags field of OVS_ACTION_ATTR_ADD_MPLS
> * argument.
> * @OVS_ACTION_ATTR_DROP: Explicit drop action.
> + * @OVS_ACTION_ATTR_EMIT_SAMPLE: Send a sample of the packet to external
> + * observers via psample.
> *
> * Only a single header can be set with a single %OVS_ACTION_ATTR_SET. Not all
> * fields within a header are modifiable, e.g. the IPv4 protocol and fragment
> @@ -1004,6 +1031,7 @@ enum ovs_action_attr {
> OVS_ACTION_ATTR_ADD_MPLS, /* struct ovs_action_add_mpls. */
> OVS_ACTION_ATTR_DEC_TTL, /* Nested OVS_DEC_TTL_ATTR_*. */
> OVS_ACTION_ATTR_DROP, /* u32 error code. */
> + OVS_ACTION_ATTR_EMIT_SAMPLE, /* Nested OVS_EMIT_SAMPLE_ATTR_*. */
>
> __OVS_ACTION_ATTR_MAX, /* Nothing past this will be accepted
> * from userspace. */
> diff --git a/net/openvswitch/Kconfig b/net/openvswitch/Kconfig
> index 29a7081858cd..2535f3f9f462 100644
> --- a/net/openvswitch/Kconfig
> +++ b/net/openvswitch/Kconfig
> @@ -10,6 +10,7 @@ config OPENVSWITCH
> (NF_CONNTRACK && ((!NF_DEFRAG_IPV6 || NF_DEFRAG_IPV6) && \
> (!NF_NAT || NF_NAT) && \
> (!NETFILTER_CONNCOUNT || NETFILTER_CONNCOUNT)))
> + depends on PSAMPLE || !PSAMPLE
> select LIBCRC32C
> select MPLS
> select NET_MPLS_GSO
> diff --git a/net/openvswitch/actions.c b/net/openvswitch/actions.c
> index 964225580824..1f555cbba312 100644
> --- a/net/openvswitch/actions.c
> +++ b/net/openvswitch/actions.c
> @@ -24,6 +24,11 @@
> #include <net/checksum.h>
> #include <net/dsfield.h>
> #include <net/mpls.h>
> +
> +#if IS_ENABLED(CONFIG_PSAMPLE)
> +#include <net/psample.h>
> +#endif
> +
> #include <net/sctp/checksum.h>
>
> #include "datapath.h"
> @@ -1299,6 +1304,37 @@ static int execute_dec_ttl(struct sk_buff *skb, struct sw_flow_key *key)
> return 0;
> }
>
> +static void execute_emit_sample(struct datapath *dp, struct sk_buff *skb,
> + const struct sw_flow_key *key,
The 'key' is not used in the function.
> + const struct nlattr *attr)
> +{
> +#if IS_ENABLED(CONFIG_PSAMPLE)
IIUC, the general coding style guideline is to compile out the whole
function, instead of only the parts. i.e. something like:
#if IS_ENABLED(CONFIG_PSAMPLE)
static void execute_emit_sample(...) {
<body>
}
#else
#define execute_emit_sample(dp, skb, attr)
#endif
Otherwise, we'll also need to mark the arguments with __maybe_unused.
The rest of the patch looks good to me.
Best regards, Ilya Maximets.
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