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Date: Mon, 20 Nov 2023 18:50:22 -0800
From: Jakub Kicinski <kuba@kernel.org>
To: Jiri Pirko <jiri@resnulli.us>
Cc: netdev@vger.kernel.org, pabeni@redhat.com, davem@davemloft.net,
 edumazet@google.com, jacob.e.keller@intel.com, jhs@mojatatu.com,
 johannes@sipsolutions.net, andriy.shevchenko@linux.intel.com,
 amritha.nambiar@intel.com, sdf@google.com, horms@kernel.org
Subject: Re: [patch net-next v3 5/9] genetlink: implement release callback
 and free sk_user_data there
Message-ID: <20231120185022.78f10188@kernel.org>
In-Reply-To: <20231120084657.458076-6-jiri@resnulli.us>
References: <20231120084657.458076-1-jiri@resnulli.us>
	<20231120084657.458076-6-jiri@resnulli.us>
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On Mon, 20 Nov 2023 09:46:53 +0100 Jiri Pirko wrote:
> 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.

How is this supposed to work?

genetlink sockets are not bound to a family. User can use a single
socket to subscribe to notifications from all families and presumably
each one of the would interpret sk->sk_user_data as their own state?

You need to store the state locally in the family, keyed
on pid, and free it using the NETLINK_URELEASE notifier...