netdev - [net-next v3 4/8] seg6: add callbacks for customizing the creation/destruction of a behavior

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Message-Id: <20201123182857.4640-5-andrea.mayer@uniroma2.it>
Date:   Mon, 23 Nov 2020 19:28:52 +0100
From:   Andrea Mayer <andrea.mayer@...roma2.it>
To:     "David S. Miller" <davem@...emloft.net>,
        David Ahern <dsahern@...nel.org>,
        Alexey Kuznetsov <kuznet@....inr.ac.ru>,
        Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
        Jakub Kicinski <kuba@...nel.org>,
        Shuah Khan <shuah@...nel.org>,
        Shrijeet Mukherjee <shrijeet@...il.com>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...omium.org>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-kselftest@...r.kernel.org
Cc:     Nathan Chancellor <natechancellor@...il.com>,
        Stefano Salsano <stefano.salsano@...roma2.it>,
        Paolo Lungaroni <paolo.lungaroni@...t.it>,
        Ahmed Abdelsalam <ahabdels.dev@...il.com>,
        Andrea Mayer <andrea.mayer@...roma2.it>
Subject: [net-next v3 4/8] seg6: add callbacks for customizing the creation/destruction of a behavior

We introduce two callbacks used for customizing the creation/destruction of
a SRv6 behavior. Such callbacks are defined in the new struct
seg6_local_lwtunnel_ops and hereafter we provide a brief description of
them:

 - build_state(...): used for calling the custom constructor of the
   behavior during its initialization phase and after all the attributes
   have been parsed successfully;

 - destroy_state(...): used for calling the custom destructor of the
   behavior before it is completely destroyed.

Signed-off-by: Andrea Mayer <andrea.mayer@...roma2.it>
---
 net/ipv6/seg6_local.c | 49 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 49 insertions(+)

diff --git a/net/ipv6/seg6_local.c b/net/ipv6/seg6_local.c
index 3b5657c622a0..da5bf4167a52 100644
--- a/net/ipv6/seg6_local.c
+++ b/net/ipv6/seg6_local.c
@@ -33,6 +33,13 @@
 
 struct seg6_local_lwt;
 
+/* callbacks used for customizing the creation and destruction of a behavior */
+struct seg6_local_lwtunnel_ops {
+	int (*build_state)(struct seg6_local_lwt *slwt, const void *cfg,
+			   struct netlink_ext_ack *extack);
+	void (*destroy_state)(struct seg6_local_lwt *slwt);
+};
+
 struct seg6_action_desc {
 	int action;
 	unsigned long attrs;
@@ -53,6 +60,8 @@ struct seg6_action_desc {
 
 	int (*input)(struct sk_buff *skb, struct seg6_local_lwt *slwt);
 	int static_headroom;
+
+	struct seg6_local_lwtunnel_ops slwt_ops;
 };
 
 struct bpf_lwt_prog {
@@ -1055,6 +1064,38 @@ static int parse_nla_optional_attrs(struct nlattr **attrs,
 	return err;
 }
 
+/* call the custom constructor of the behavior during its initialization phase
+ * and after that all its attributes have been parsed successfully.
+ */
+static int
+seg6_local_lwtunnel_build_state(struct seg6_local_lwt *slwt, const void *cfg,
+				struct netlink_ext_ack *extack)
+{
+	struct seg6_action_desc *desc = slwt->desc;
+	struct seg6_local_lwtunnel_ops *ops;
+
+	ops = &desc->slwt_ops;
+	if (!ops->build_state)
+		return 0;
+
+	return ops->build_state(slwt, cfg, extack);
+}
+
+/* call the custom destructor of the behavior which is invoked before the
+ * tunnel is going to be destroyed.
+ */
+static void seg6_local_lwtunnel_destroy_state(struct seg6_local_lwt *slwt)
+{
+	struct seg6_action_desc *desc = slwt->desc;
+	struct seg6_local_lwtunnel_ops *ops;
+
+	ops = &desc->slwt_ops;
+	if (!ops->destroy_state)
+		return;
+
+	ops->destroy_state(slwt);
+}
+
 static int parse_nla_action(struct nlattr **attrs, struct seg6_local_lwt *slwt)
 {
 	struct seg6_action_param *param;
@@ -1154,6 +1195,10 @@ static int seg6_local_build_state(struct net *net, struct nlattr *nla,
 	if (err < 0)
 		goto out_free;
 
+	err = seg6_local_lwtunnel_build_state(slwt, cfg, extack);
+	if (err < 0)
+		goto out_destroy_attrs;
+
 	newts->type = LWTUNNEL_ENCAP_SEG6_LOCAL;
 	newts->flags = LWTUNNEL_STATE_INPUT_REDIRECT;
 	newts->headroom = slwt->headroom;
@@ -1162,6 +1207,8 @@ static int seg6_local_build_state(struct net *net, struct nlattr *nla,
 
 	return 0;
 
+out_destroy_attrs:
+	destroy_attrs(slwt);
 out_free:
 	kfree(newts);
 	return err;
@@ -1171,6 +1218,8 @@ static void seg6_local_destroy_state(struct lwtunnel_state *lwt)
 {
 	struct seg6_local_lwt *slwt = seg6_local_lwtunnel(lwt);
 
+	seg6_local_lwtunnel_destroy_state(slwt);
+
 	destroy_attrs(slwt);
 
 	return;
-- 
2.20.1