netdev - [patch net-next v2 5/9] genetlink: implement release callback and free sk_user

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Date: Thu, 16 Nov 2023 17:48:17 +0100
From: Jiri Pirko <jiri@...nulli.us>
To: netdev@...r.kernel.org
Cc: kuba@...nel.org,
	pabeni@...hat.com,
	davem@...emloft.net,
	edumazet@...gle.com,
	jacob.e.keller@...el.com,
	jhs@...atatu.com,
	johannes@...solutions.net,
	andriy.shevchenko@...ux.intel.com,
	amritha.nambiar@...el.com,
	sdf@...gle.com
Subject: [patch net-next v2 5/9] genetlink: implement release callback and free sk_user_data there

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

If any generic netlink family would like to allocate data store the
pointer to sk_user_data, there is no way to do cleanup in the family
code.

Assume that kfree() is good for now, as the only user introduced by the
follow-up patch (devlink) will use kzalloc() for the allocation of
the memory pointed by a pointer stored in sk_user_data. If later on
this needs to be implemented per-family, a callback is going
to be needed. Until then (if ever), do this in a simple way.

Signed-off-by: Jiri Pirko <jiri@...dia.com>
---
 net/netlink/genetlink.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/net/netlink/genetlink.c b/net/netlink/genetlink.c
index 92ef5ed2e7b0..905c5a167f53 100644
--- a/net/netlink/genetlink.c
+++ b/net/netlink/genetlink.c
@@ -1699,12 +1699,18 @@ static int genl_bind(struct net *net, int group)
 	return ret;
 }
 
+static void genl_release(struct sock *sk, unsigned long *groups)
+{
+	kfree(sk->sk_user_data);
+}
+
 static int __net_init genl_pernet_init(struct net *net)
 {
 	struct netlink_kernel_cfg cfg = {
 		.input		= genl_rcv,
 		.flags		= NL_CFG_F_NONROOT_RECV,
 		.bind		= genl_bind,
+		.release	= genl_release,
 	};
 
 	/* we'll bump the group number right afterwards */
-- 
2.41.0