[PATCH mptcp-next v2 2/6] mptcp: convert netlink from small_ops to ops

Davide Caratti posted 6 patches 8 months, 3 weeks ago
Maintainers: Jonathan Corbet <corbet@lwn.net>, "David S. Miller" <davem@davemloft.net>, Eric Dumazet <edumazet@google.com>, Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>, Matthieu Baerts <matthieu.baerts@tessares.net>, Mat Martineau <martineau@kernel.org>
[PATCH mptcp-next v2 2/6] mptcp: convert netlink from small_ops to ops
Posted by Davide Caratti 8 months, 3 weeks ago
in the current MPTCP control plane, all operations use a netlink
attribute of the same type "MPTCP_PM_ATTR". However, add/del/get/flush
operations only parse the first element in the message _ the one that
describes MPTCP endpoints (that was named MPTCP_PM_ATTR_ADDR and
mostly used in ADD_ADDR operations _ probably the similarity of "attr",
"addr" and "add" might cause some confusion to human readers).
Convert MPTCP from 'small_ops' to 'ops', thus allowing different attributes
for each single operation, hopefully makes all this clearer to human
readers.

- use a separate attribute set for add/del/get/flush address operation,
  binary compatible with the existing one, to store the endpoint address.
  MPTCP_PM_ENDPOINT_ADDR is added to the uAPI (with the same value as
  MPTCP_PM_ATTR_ADDR) for these operations.
- convert mptcp_pm_ops[] and add policy files accordingly.

this prepares MPTCP control plane to be described as YAML spec.

Link: https://github.com/multipath-tcp/mptcp_net-next/issues/340
Signed-off-by: Davide Caratti <dcaratti@redhat.com>
---
 include/uapi/linux/mptcp.h |   8 ++
 net/mptcp/pm_netlink.c     | 185 ++++++++++++++++++++++++-------------
 2 files changed, 129 insertions(+), 64 deletions(-)

diff --git a/include/uapi/linux/mptcp.h b/include/uapi/linux/mptcp.h
index ee9c49f949a2..34082c14c89b 100644
--- a/include/uapi/linux/mptcp.h
+++ b/include/uapi/linux/mptcp.h
@@ -65,6 +65,14 @@ enum {
 
 #define MPTCP_PM_ATTR_MAX (__MPTCP_PM_ATTR_MAX - 1)
 
+enum {
+        MPTCP_PM_ENDPOINT_ADDR = 1,
+
+        __MPTCP_PM_ENDPOINT_MAX
+};
+
+#define MPTCP_PM_ENDPOINT_MAX (__MPTCP_PM_ENDPOINT_MAX - 1)
+
 enum {
 	MPTCP_PM_ADDR_ATTR_UNSPEC,
 
diff --git a/net/mptcp/pm_netlink.c b/net/mptcp/pm_netlink.c
index 9661f3812682..3859a206c298 100644
--- a/net/mptcp/pm_netlink.c
+++ b/net/mptcp/pm_netlink.c
@@ -48,6 +48,53 @@ struct pm_nl_pernet {
 #define MPTCP_PM_ADDR_MAX	8
 #define ADD_ADDR_RETRANS_MAX	3
 
+const struct nla_policy mptcp_pm_address_nl_policy[MPTCP_PM_ADDR_ATTR_IF_IDX + 1] = {
+	[MPTCP_PM_ADDR_ATTR_FAMILY] = { .type = NLA_U16, },
+	[MPTCP_PM_ADDR_ATTR_ADDR4] = { .type = NLA_U32, },
+	[MPTCP_PM_ADDR_ATTR_ADDR6] = { .len = 16, },
+	[MPTCP_PM_ADDR_ATTR_ID] = { .type = NLA_U8, },
+	[MPTCP_PM_ADDR_ATTR_PORT] = { .type = NLA_U16, },
+	[MPTCP_PM_ADDR_ATTR_IF_IDX] = { .type = NLA_S32, },
+	[MPTCP_PM_ADDR_ATTR_FLAGS] = { .type = NLA_U32, },
+};
+
+/* MPTCP_PM_CMD_ADD_ADDR / DEL / GET / FLUSH - do */
+static const struct nla_policy mptcp_pm_endpoint_nl_policy[MPTCP_PM_ENDPOINT_ADDR + 1] = {
+	[MPTCP_PM_ENDPOINT_ADDR] = NLA_POLICY_NESTED(mptcp_pm_address_nl_policy),
+};
+
+/* MPTCP_PM_CMD_SET_LIMITS - do */
+static const struct nla_policy mptcp_pm_set_limits_nl_policy[MPTCP_PM_ATTR_SUBFLOWS + 1] = {
+	[MPTCP_PM_ATTR_RCV_ADD_ADDRS] = { .type = NLA_U32, },
+	[MPTCP_PM_ATTR_SUBFLOWS] = { .type = NLA_U32, },
+};
+
+/* MPTCP_PM_CMD_SET_FLAGS - do */
+const struct nla_policy mptcp_pm_set_flags_nl_policy[MPTCP_PM_ATTR_ADDR_REMOTE + 1] = {
+        [MPTCP_PM_ATTR_ADDR] = NLA_POLICY_NESTED(mptcp_pm_address_nl_policy),
+        [MPTCP_PM_ATTR_ADDR_REMOTE] = NLA_POLICY_NESTED(mptcp_pm_address_nl_policy),
+        [MPTCP_PM_ATTR_TOKEN] = { .type = NLA_U32, },
+};
+
+/* MPTCP_PM_CMD_ANNOUNCE - do */
+static const struct nla_policy mptcp_pm_announce_nl_policy[MPTCP_PM_ATTR_TOKEN + 1] = {
+	[MPTCP_PM_ATTR_TOKEN] = { .type = NLA_U32, },
+	[MPTCP_PM_ATTR_ADDR] = NLA_POLICY_NESTED(mptcp_pm_address_nl_policy),
+};
+
+/* MPTCP_PM_CMD_REMOVE - do */
+static const struct nla_policy mptcp_pm_remove_nl_policy[MPTCP_PM_ATTR_LOC_ID + 1] = {
+	[MPTCP_PM_ATTR_TOKEN] = { .type = NLA_U32, },
+	[MPTCP_PM_ATTR_LOC_ID] = { .type = NLA_U8, },
+};
+
+/* MPTCP_PM_CMD_SUBFLOW_CREATE / DESTROY - do */
+static const struct nla_policy mptcp_pm_subflow_create_nl_policy[MPTCP_PM_ATTR_ADDR_REMOTE + 1] = {
+	[MPTCP_PM_ATTR_ADDR_REMOTE] = NLA_POLICY_NESTED(mptcp_pm_address_nl_policy),
+	[MPTCP_PM_ATTR_TOKEN] = { .type = NLA_U32, },
+	[MPTCP_PM_ATTR_ADDR] = NLA_POLICY_NESTED(mptcp_pm_address_nl_policy),
+};
+
 static struct pm_nl_pernet *pm_nl_get_pernet(const struct net *net)
 {
 	return net_generic(net, pm_nl_pernet_id);
@@ -1104,29 +1151,6 @@ static const struct genl_multicast_group mptcp_pm_mcgrps[] = {
 					  },
 };
 
-static const struct nla_policy
-mptcp_pm_addr_policy[MPTCP_PM_ADDR_ATTR_MAX + 1] = {
-	[MPTCP_PM_ADDR_ATTR_FAMILY]	= { .type	= NLA_U16,	},
-	[MPTCP_PM_ADDR_ATTR_ID]		= { .type	= NLA_U8,	},
-	[MPTCP_PM_ADDR_ATTR_ADDR4]	= { .type	= NLA_U32,	},
-	[MPTCP_PM_ADDR_ATTR_ADDR6]	=
-		NLA_POLICY_EXACT_LEN(sizeof(struct in6_addr)),
-	[MPTCP_PM_ADDR_ATTR_PORT]	= { .type	= NLA_U16	},
-	[MPTCP_PM_ADDR_ATTR_FLAGS]	= { .type	= NLA_U32	},
-	[MPTCP_PM_ADDR_ATTR_IF_IDX]     = { .type	= NLA_S32	},
-};
-
-static const struct nla_policy mptcp_pm_policy[MPTCP_PM_ATTR_MAX + 1] = {
-	[MPTCP_PM_ATTR_ADDR]		=
-					NLA_POLICY_NESTED(mptcp_pm_addr_policy),
-	[MPTCP_PM_ATTR_RCV_ADD_ADDRS]	= { .type	= NLA_U32,	},
-	[MPTCP_PM_ATTR_SUBFLOWS]	= { .type	= NLA_U32,	},
-	[MPTCP_PM_ATTR_TOKEN]		= { .type	= NLA_U32,	},
-	[MPTCP_PM_ATTR_LOC_ID]		= { .type	= NLA_U8,	},
-	[MPTCP_PM_ATTR_ADDR_REMOTE]	=
-					NLA_POLICY_NESTED(mptcp_pm_addr_policy),
-};
-
 void mptcp_pm_nl_subflow_chk_stale(const struct mptcp_sock *msk, struct sock *ssk)
 {
 	struct mptcp_subflow_context *iter, *subflow = mptcp_subflow_ctx(ssk);
@@ -1188,7 +1212,7 @@ static int mptcp_pm_parse_pm_addr_attr(struct nlattr *tb[],
 
 	/* no validation needed - was already done via nested policy */
 	err = nla_parse_nested_deprecated(tb, MPTCP_PM_ADDR_ATTR_MAX, attr,
-					  mptcp_pm_addr_policy, info->extack);
+					  mptcp_pm_address_nl_policy, info->extack);
 	if (err)
 		return err;
 
@@ -1305,7 +1329,7 @@ static int mptcp_nl_add_subflow_or_signal_addr(struct net *net)
 
 static int mptcp_nl_cmd_add_addr(struct sk_buff *skb, struct genl_info *info)
 {
-	struct nlattr *attr = info->attrs[MPTCP_PM_ATTR_ADDR];
+	struct nlattr *attr = info->attrs[MPTCP_PM_ENDPOINT_ADDR];
 	struct pm_nl_pernet *pernet = genl_info_pm_nl(info);
 	struct mptcp_pm_addr_entry addr, *entry;
 	int ret;
@@ -1486,7 +1510,7 @@ static int mptcp_nl_remove_id_zero_address(struct net *net,
 
 static int mptcp_nl_cmd_del_addr(struct sk_buff *skb, struct genl_info *info)
 {
-	struct nlattr *attr = info->attrs[MPTCP_PM_ATTR_ADDR];
+	struct nlattr *attr = info->attrs[MPTCP_PM_ENDPOINT_ADDR];
 	struct pm_nl_pernet *pernet = genl_info_pm_nl(info);
 	struct mptcp_pm_addr_entry addr, *entry;
 	unsigned int addr_max;
@@ -1677,7 +1701,7 @@ static int mptcp_nl_fill_addr(struct sk_buff *skb,
 
 static int mptcp_nl_cmd_get_addr(struct sk_buff *skb, struct genl_info *info)
 {
-	struct nlattr *attr = info->attrs[MPTCP_PM_ATTR_ADDR];
+	struct nlattr *attr = info->attrs[MPTCP_PM_ENDPOINT_ADDR];
 	struct pm_nl_pernet *pernet = genl_info_pm_nl(info);
 	struct mptcp_pm_addr_entry addr, *entry;
 	struct sk_buff *msg;
@@ -2283,72 +2307,105 @@ void mptcp_event(enum mptcp_event_type type, const struct mptcp_sock *msk,
 	nlmsg_free(skb);
 }
 
-static const struct genl_small_ops mptcp_pm_ops[] = {
+
+static const struct genl_ops mptcp_pm_ops[] = {
 	{
-		.cmd    = MPTCP_PM_CMD_ADD_ADDR,
-		.doit   = mptcp_nl_cmd_add_addr,
-		.flags  = GENL_UNS_ADMIN_PERM,
+		.cmd		= MPTCP_PM_CMD_ADD_ADDR,
+		.validate	= GENL_DONT_VALIDATE_STRICT,
+		.doit		= mptcp_nl_cmd_add_addr,
+		.policy		= mptcp_pm_endpoint_nl_policy,
+		.maxattr	= MPTCP_PM_ENDPOINT_ADDR,
+		.flags		= GENL_UNS_ADMIN_PERM,
 	},
 	{
-		.cmd    = MPTCP_PM_CMD_DEL_ADDR,
-		.doit   = mptcp_nl_cmd_del_addr,
-		.flags  = GENL_UNS_ADMIN_PERM,
+		.cmd		= MPTCP_PM_CMD_DEL_ADDR,
+		.validate	= GENL_DONT_VALIDATE_STRICT,
+		.doit		= mptcp_nl_cmd_del_addr,
+		.policy		= mptcp_pm_endpoint_nl_policy,
+		.maxattr	= MPTCP_PM_ENDPOINT_ADDR,
+		.flags		= GENL_UNS_ADMIN_PERM,
 	},
 	{
-		.cmd    = MPTCP_PM_CMD_FLUSH_ADDRS,
-		.doit   = mptcp_nl_cmd_flush_addrs,
-		.flags  = GENL_UNS_ADMIN_PERM,
+		.cmd		= MPTCP_PM_CMD_GET_ADDR,
+		.validate	= GENL_DONT_VALIDATE_STRICT,
+		.doit		= mptcp_nl_cmd_get_addr,
+		.dumpit		= mptcp_nl_cmd_dump_addrs,
+		.policy		= mptcp_pm_endpoint_nl_policy,
+		.maxattr	= MPTCP_PM_ENDPOINT_ADDR,
+		.flags		= GENL_UNS_ADMIN_PERM,
 	},
 	{
-		.cmd    = MPTCP_PM_CMD_GET_ADDR,
-		.doit   = mptcp_nl_cmd_get_addr,
-		.dumpit   = mptcp_nl_cmd_dump_addrs,
+		.cmd		= MPTCP_PM_CMD_FLUSH_ADDRS,
+		.validate	= GENL_DONT_VALIDATE_STRICT,
+		.doit		= mptcp_nl_cmd_flush_addrs,
+		.policy		= mptcp_pm_endpoint_nl_policy,
+		.maxattr	= MPTCP_PM_ENDPOINT_ADDR,
+		.flags		= GENL_UNS_ADMIN_PERM,
 	},
 	{
-		.cmd    = MPTCP_PM_CMD_SET_LIMITS,
-		.doit   = mptcp_nl_cmd_set_limits,
-		.flags  = GENL_UNS_ADMIN_PERM,
+		.cmd		= MPTCP_PM_CMD_SET_LIMITS,
+		.validate	= GENL_DONT_VALIDATE_STRICT,
+		.doit		= mptcp_nl_cmd_set_limits,
+		.policy		= mptcp_pm_set_limits_nl_policy,
+		.maxattr	= MPTCP_PM_ATTR_SUBFLOWS,
+		.flags		= GENL_UNS_ADMIN_PERM,
 	},
 	{
-		.cmd    = MPTCP_PM_CMD_GET_LIMITS,
-		.doit   = mptcp_nl_cmd_get_limits,
+		.cmd		= MPTCP_PM_CMD_GET_LIMITS,
+		.validate	= GENL_DONT_VALIDATE_STRICT,
+		.doit		= mptcp_nl_cmd_get_limits,
+		.policy		= mptcp_pm_set_limits_nl_policy,
+		.maxattr	= MPTCP_PM_ATTR_SUBFLOWS,
 	},
 	{
-		.cmd    = MPTCP_PM_CMD_SET_FLAGS,
-		.doit   = mptcp_nl_cmd_set_flags,
-		.flags  = GENL_UNS_ADMIN_PERM,
+		.cmd		= MPTCP_PM_CMD_SET_FLAGS,
+		.validate	= GENL_DONT_VALIDATE_STRICT,
+		.doit		= mptcp_nl_cmd_set_flags,
+		.policy		= mptcp_pm_set_flags_nl_policy,
+		.maxattr	= MPTCP_PM_ATTR_ADDR_REMOTE,
+		.flags		= GENL_UNS_ADMIN_PERM,
 	},
 	{
-		.cmd    = MPTCP_PM_CMD_ANNOUNCE,
-		.doit   = mptcp_nl_cmd_announce,
-		.flags  = GENL_UNS_ADMIN_PERM,
+		.cmd		= MPTCP_PM_CMD_ANNOUNCE,
+		.validate	= GENL_DONT_VALIDATE_STRICT,
+		.doit		= mptcp_nl_cmd_announce,
+		.policy		= mptcp_pm_announce_nl_policy,
+		.maxattr	= MPTCP_PM_ATTR_TOKEN,
+		.flags		= GENL_UNS_ADMIN_PERM,
 	},
 	{
-		.cmd    = MPTCP_PM_CMD_REMOVE,
-		.doit   = mptcp_nl_cmd_remove,
-		.flags  = GENL_UNS_ADMIN_PERM,
+		.cmd		= MPTCP_PM_CMD_REMOVE,
+		.validate	= GENL_DONT_VALIDATE_STRICT,
+		.doit		= mptcp_nl_cmd_remove,
+		.policy		= mptcp_pm_remove_nl_policy,
+		.maxattr	= MPTCP_PM_ATTR_LOC_ID,
+		.flags		= GENL_UNS_ADMIN_PERM,
 	},
 	{
-		.cmd    = MPTCP_PM_CMD_SUBFLOW_CREATE,
-		.doit   = mptcp_nl_cmd_sf_create,
-		.flags  = GENL_UNS_ADMIN_PERM,
+		.cmd		= MPTCP_PM_CMD_SUBFLOW_CREATE,
+		.validate	= GENL_DONT_VALIDATE_STRICT,
+		.doit		= mptcp_nl_cmd_sf_create,
+		.policy		= mptcp_pm_subflow_create_nl_policy,
+		.maxattr	= MPTCP_PM_ATTR_ADDR_REMOTE,
+		.flags		= GENL_UNS_ADMIN_PERM,
 	},
 	{
-		.cmd    = MPTCP_PM_CMD_SUBFLOW_DESTROY,
-		.doit   = mptcp_nl_cmd_sf_destroy,
-		.flags  = GENL_UNS_ADMIN_PERM,
+		.cmd		= MPTCP_PM_CMD_SUBFLOW_DESTROY,
+		.validate	= GENL_DONT_VALIDATE_STRICT,
+		.doit		= mptcp_nl_cmd_sf_destroy,
+		.policy		= mptcp_pm_subflow_create_nl_policy,
+		.maxattr	= MPTCP_PM_ATTR_ADDR_REMOTE,
+		.flags		= GENL_UNS_ADMIN_PERM,
 	},
 };
 
 static struct genl_family mptcp_genl_family __ro_after_init = {
 	.name		= MPTCP_PM_NAME,
 	.version	= MPTCP_PM_VER,
-	.maxattr	= MPTCP_PM_ATTR_MAX,
-	.policy		= mptcp_pm_policy,
 	.netnsok	= true,
 	.module		= THIS_MODULE,
-	.small_ops	= mptcp_pm_ops,
-	.n_small_ops	= ARRAY_SIZE(mptcp_pm_ops),
+	.ops		= mptcp_pm_ops,
+	.n_ops		= ARRAY_SIZE(mptcp_pm_ops),
 	.resv_start_op	= MPTCP_PM_CMD_SUBFLOW_DESTROY + 1,
 	.mcgrps		= mptcp_pm_mcgrps,
 	.n_mcgrps	= ARRAY_SIZE(mptcp_pm_mcgrps),
-- 
2.40.1
Re: [PATCH mptcp-next v2 2/6] mptcp: convert netlink from small_ops to ops
Posted by Paolo Abeni 8 months, 3 weeks ago
On Fri, 2023-09-01 at 20:10 +0200, Davide Caratti wrote:
> in the current MPTCP control plane, all operations use a netlink
> attribute of the same type "MPTCP_PM_ATTR". However, add/del/get/flush
> operations only parse the first element in the message _ the one that
> describes MPTCP endpoints (that was named MPTCP_PM_ATTR_ADDR and
> mostly used in ADD_ADDR operations _ probably the similarity of "attr",
> "addr" and "add" might cause some confusion to human readers).
> Convert MPTCP from 'small_ops' to 'ops', thus allowing different attributes
> for each single operation, hopefully makes all this clearer to human
> readers.

Minor nit: I'm wondering if it would make sense factoring out only the
bits replacing MPTCP_PM_ATTR_ADDR with MPTCP_PM_ENDPOINT_ADDR, to make
it clearer what is happening here.

Likely not a big deal either ways. 
 
> diff --git a/net/mptcp/pm_netlink.c b/net/mptcp/pm_netlink.c
> index 9661f3812682..3859a206c298 100644
> --- a/net/mptcp/pm_netlink.c
> +++ b/net/mptcp/pm_netlink.c
> @@ -48,6 +48,53 @@ struct pm_nl_pernet {
>  #define MPTCP_PM_ADDR_MAX	8
>  #define ADD_ADDR_RETRANS_MAX	3
>  
> +const struct nla_policy mptcp_pm_address_nl_policy[MPTCP_PM_ADDR_ATTR_IF_IDX + 1] = {

The above is a little confusing...

> +	[MPTCP_PM_ADDR_ATTR_FAMILY] = { .type = NLA_U16, },
> +	[MPTCP_PM_ADDR_ATTR_ADDR4] = { .type = NLA_U32, },
> +	[MPTCP_PM_ADDR_ATTR_ADDR6] = { .len = 16, },
> +	[MPTCP_PM_ADDR_ATTR_ID] = { .type = NLA_U8, },
> +	[MPTCP_PM_ADDR_ATTR_PORT] = { .type = NLA_U16, },
> +	[MPTCP_PM_ADDR_ATTR_IF_IDX] = { .type = NLA_S32, },
> +	[MPTCP_PM_ADDR_ATTR_FLAGS] = { .type = NLA_U32, },
> +};

... given that MPTCP_PM_ADDR_ATTR_IF_IDX is not listed last here.

I guess this layout has been chosen to match what the tool generates
for the spec, right?

What if we reorder the 'attributes' in 'operations/list' in patch 3/6
to respect the corresponding numeric order? would that lead to more
natural order here, too?

Thanks!

/P
Re: [PATCH mptcp-next v2 2/6] mptcp: convert netlink from small_ops to ops
Posted by Davide Caratti 8 months, 3 weeks ago
hello Paolo, thanks for looking at this!

On Mon, Sep 04, 2023 at 11:13:15AM +0200, Paolo Abeni wrote:
> On Fri, 2023-09-01 at 20:10 +0200, Davide Caratti wrote:
> > in the current MPTCP control plane, all operations use a netlink
> > attribute of the same type "MPTCP_PM_ATTR". However, add/del/get/flush
> > operations only parse the first element in the message _ the one that
> > describes MPTCP endpoints (that was named MPTCP_PM_ATTR_ADDR and
> > mostly used in ADD_ADDR operations _ probably the similarity of "attr",
> > "addr" and "add" might cause some confusion to human readers).
> > Convert MPTCP from 'small_ops' to 'ops', thus allowing different attributes
> > for each single operation, hopefully makes all this clearer to human
> > readers.
> 
> Minor nit: I'm wondering if it would make sense factoring out only the
> bits replacing MPTCP_PM_ATTR_ADDR with MPTCP_PM_ENDPOINT_ADDR, to make
> it clearer what is happening here.

I think the addition of MPTCP_PM_ENDPOINT_ADDR and its use in add/del/get/flush
operation would have little/no sense with small_ops. It's there to avoid
selecting an element in 'endpoint' using the same label we use to
get the local address form 'attr'.
 
> Likely not a big deal either ways.

I'd like to keep one single patch that does the 'small_ops' ->
'ops' conversion (to avoid adding a hidden dependency to future patches
that will fix this patch. You know, there are those fancy tools that select
follow-ups commits ;) ).

>  
> > diff --git a/net/mptcp/pm_netlink.c b/net/mptcp/pm_netlink.c
> > index 9661f3812682..3859a206c298 100644
> > --- a/net/mptcp/pm_netlink.c
> > +++ b/net/mptcp/pm_netlink.c
> > @@ -48,6 +48,53 @@ struct pm_nl_pernet {
> >  #define MPTCP_PM_ADDR_MAX	8
> >  #define ADD_ADDR_RETRANS_MAX	3
> >  
> > +const struct nla_policy mptcp_pm_address_nl_policy[MPTCP_PM_ADDR_ATTR_IF_IDX + 1] = {
> 
> The above is a little confusing...
> 
> > +	[MPTCP_PM_ADDR_ATTR_FAMILY] = { .type = NLA_U16, },
> > +	[MPTCP_PM_ADDR_ATTR_ADDR4] = { .type = NLA_U32, },
> > +	[MPTCP_PM_ADDR_ATTR_ADDR6] = { .len = 16, },
> > +	[MPTCP_PM_ADDR_ATTR_ID] = { .type = NLA_U8, },
> > +	[MPTCP_PM_ADDR_ATTR_PORT] = { .type = NLA_U16, },
> > +	[MPTCP_PM_ADDR_ATTR_IF_IDX] = { .type = NLA_S32, },
> > +	[MPTCP_PM_ADDR_ATTR_FLAGS] = { .type = NLA_U32, },
> > +};
> 
> ... given that MPTCP_PM_ADDR_ATTR_IF_IDX is not listed last here.

dood catch,
 
> I guess this layout has been chosen to match what the tool generates
> for the spec, right?

no no, it's just misplaced :) . Let me fix it and I'll post v3.

> 
> What if we reorder the 'attributes' in 'operations/list' in patch 3/6
> to respect the corresponding numeric order? would that lead to more
> natural order here, too?

in patch 3/6 they are actually respecting the numeric order: otherwise
the uAPI would be broken (e.g. a userspace program would see a value
change in one or more enum elements).

I see that we have some spots like:

 382       do: &sf_create
 383         request:
 384           attributes:
 385             - addr_remote
                     ^^^ this is out-of-order, but  the C code is generated correctly
 386             - token
                     ^^^ same here
 387             - addr


they can be fixed with in patch 3 v3, but that will have with no effect on the
generated C code. Did I get correctly the change request?
Re: [PATCH mptcp-next v2 2/6] mptcp: convert netlink from small_ops to ops
Posted by Paolo Abeni 8 months, 3 weeks ago
On Mon, 2023-09-04 at 17:20 +0200, Davide Caratti wrote:
> hello Paolo, thanks for looking at this!
> 
> On Mon, Sep 04, 2023 at 11:13:15AM +0200, Paolo Abeni wrote:
> > On Fri, 2023-09-01 at 20:10 +0200, Davide Caratti wrote:
> > > in the current MPTCP control plane, all operations use a netlink
> > > attribute of the same type "MPTCP_PM_ATTR". However, add/del/get/flush
> > > operations only parse the first element in the message _ the one that
> > > describes MPTCP endpoints (that was named MPTCP_PM_ATTR_ADDR and
> > > mostly used in ADD_ADDR operations _ probably the similarity of "attr",
> > > "addr" and "add" might cause some confusion to human readers).
> > > Convert MPTCP from 'small_ops' to 'ops', thus allowing different attributes
> > > for each single operation, hopefully makes all this clearer to human
> > > readers.
> > 
> > Minor nit: I'm wondering if it would make sense factoring out only the
> > bits replacing MPTCP_PM_ATTR_ADDR with MPTCP_PM_ENDPOINT_ADDR, to make
> > it clearer what is happening here.
> 
> I think the addition of MPTCP_PM_ENDPOINT_ADDR and its use in add/del/get/flush
> operation would have little/no sense with small_ops. It's there to avoid
> selecting an element in 'endpoint' using the same label we use to
> get the local address form 'attr'.
>  
> > Likely not a big deal either ways.
> 
> I'd like to keep one single patch that does the 'small_ops' ->
> 'ops' conversion (to avoid adding a hidden dependency to future patches
> that will fix this patch. You know, there are those fancy tools that select
> follow-ups commits ;) ).

Fine by me.
 
> > 
> > What if we reorder the 'attributes' in 'operations/list' in patch 3/6
> > to respect the corresponding numeric order? would that lead to more
> > natural order here, too?
> 
> in patch 3/6 they are actually respecting the numeric order: otherwise
> the uAPI would be broken (e.g. a userspace program would see a value
> change in one or more enum elements).
> 
> I see that we have some spots like:
> 
>  382       do: &sf_create
>  383         request:
>  384           attributes:
>  385             - addr_remote
>                      ^^^ this is out-of-order, but  the C code is generated correctly
>  386             - token
>                      ^^^ same here
>  387             - addr
> 
> 
> they can be fixed with in patch 3 v3, but that will have with no effect on the
> generated C code. 

If it has no effect on the generated code, then it's up to you
(possibly using the same order everywhere would made things clearer,
but it's a matter of personal preference).

> Did I get correctly the change request?

Yes :)

Thanks!

Paolo