netdev - [patch net-next v4 10/13] devlink: allow user to narrow per-instance dumps by passing handle attrs

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Message-ID: <20230811155714.1736405-11-jiri@resnulli.us>
Date: Fri, 11 Aug 2023 17:57:11 +0200
From: Jiri Pirko <jiri@...nulli.us>
To: netdev@...r.kernel.org
Cc: kuba@...nel.org,
	pabeni@...hat.com,
	davem@...emloft.net,
	edumazet@...gle.com,
	moshe@...dia.com,
	saeedm@...dia.com,
	idosch@...dia.com,
	petrm@...dia.com
Subject: [patch net-next v4 10/13] devlink: allow user to narrow per-instance dumps by passing handle attrs

From: Jiri Pirko <jiri@...dia.com>

For SFs, one devlink instance per SF is created. There might be
thousands of these on a single host. When a user needs to know port
handle for specific SF, he needs to dump all devlink ports on the host
which does not scale good.

Allow user to pass devlink handle attributes alongside the dump command
and dump only objects which are under selected devlink instance.

Example:
$ devlink port show
auxiliary/mlx5_core.eth.0/65535: type eth netdev eth2 flavour physical port 0 splittable false
auxiliary/mlx5_core.eth.1/131071: type eth netdev eth3 flavour physical port 1 splittable false

$ devlink port show auxiliary/mlx5_core.eth.0
auxiliary/mlx5_core.eth.0/65535: type eth netdev eth2 flavour physical port 0 splittable false

$ devlink port show auxiliary/mlx5_core.eth.1
auxiliary/mlx5_core.eth.1/131071: type eth netdev eth3 flavour physical port 1 splittable false

Signed-off-by: Jiri Pirko <jiri@...dia.com>
---
v3->v4:
- fixed NLM_F_DUMP_FILTERED setting
v2->v3:
- rebased on top of the generated split ops changes
- removed SELECTOR nested attr
- rebased on top of flags arg propagation, added NLM_F_DUMP_FILTERED
- removed no longer needed start() and done() dump callbacks
- adjusted patch subject and description to better match what
  the patch does now
v1->v2:
- extended to patch that covers all dumpit commands
- used start() and done() callback to parse the selector attr
- changed the selector attr netlink policy to be created on fly
- changed patch description accordingly
---
 net/devlink/netlink.c | 43 ++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 40 insertions(+), 3 deletions(-)

diff --git a/net/devlink/netlink.c b/net/devlink/netlink.c
index 47e44fb45815..a9b43b0c5959 100644
--- a/net/devlink/netlink.c
+++ b/net/devlink/netlink.c
@@ -170,8 +170,30 @@ void devlink_nl_post_doit(const struct genl_split_ops *ops,
 	devlink_put(devlink);
 }
 
-int devlink_nl_dumpit(struct sk_buff *msg, struct netlink_callback *cb,
-		      devlink_nl_dump_one_func_t *dump_one)
+static int devlink_nl_inst_single_dumpit(struct sk_buff *msg,
+					 struct netlink_callback *cb, int flags,
+					 devlink_nl_dump_one_func_t *dump_one,
+					 struct nlattr **attrs)
+{
+	struct devlink *devlink;
+	int err;
+
+	devlink = devlink_get_from_attrs_lock(sock_net(msg->sk), attrs);
+	if (IS_ERR(devlink))
+		return PTR_ERR(devlink);
+	err = dump_one(msg, devlink, cb, flags | NLM_F_DUMP_FILTERED);
+
+	devl_unlock(devlink);
+	devlink_put(devlink);
+
+	if (err != -EMSGSIZE)
+		return err;
+	return msg->len;
+}
+
+static int devlink_nl_inst_iter_dumpit(struct sk_buff *msg,
+				       struct netlink_callback *cb, int flags,
+				       devlink_nl_dump_one_func_t *dump_one)
 {
 	struct devlink_nl_dump_state *state = devlink_dump_state(cb);
 	struct devlink *devlink;
@@ -182,7 +204,7 @@ int devlink_nl_dumpit(struct sk_buff *msg, struct netlink_callback *cb,
 		devl_lock(devlink);
 
 		if (devl_is_registered(devlink))
-			err = dump_one(msg, devlink, cb, NLM_F_MULTI);
+			err = dump_one(msg, devlink, cb, flags);
 		else
 			err = 0;
 
@@ -203,6 +225,21 @@ int devlink_nl_dumpit(struct sk_buff *msg, struct netlink_callback *cb,
 	return msg->len;
 }
 
+int devlink_nl_dumpit(struct sk_buff *msg, struct netlink_callback *cb,
+		      devlink_nl_dump_one_func_t *dump_one)
+{
+	const struct genl_dumpit_info *info = genl_dumpit_info(cb);
+	struct nlattr **attrs = info->attrs;
+	int flags = NLM_F_MULTI;
+
+	if (attrs &&
+	    (attrs[DEVLINK_ATTR_BUS_NAME] || attrs[DEVLINK_ATTR_DEV_NAME]))
+		return devlink_nl_inst_single_dumpit(msg, cb, flags, dump_one,
+						     attrs);
+	else
+		return devlink_nl_inst_iter_dumpit(msg, cb, flags, dump_one);
+}
+
 struct genl_family devlink_nl_family __ro_after_init = {
 	.name		= DEVLINK_GENL_NAME,
 	.version	= DEVLINK_GENL_VERSION,
-- 
2.41.0