linux-kernel - Re: [PATCH 2/4] netlink: Move an assignment for the variable “sk” in __netlink_kernel

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Date: Mon, 1 Jan 2024 11:22:48 +0100
From: Markus Elfring <Markus.Elfring@....de>
To: kernel test robot <lkp@...el.com>, netdev@...r.kernel.org,
 kernel-janitors@...r.kernel.org,
 Anjali Kulkarni <anjali.k.kulkarni@...cle.com>,
 "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>,
 Jakub Kicinski <kuba@...nel.org>, Kuniyuki Iwashima <kuniyu@...zon.com>,
 Paolo Abeni <pabeni@...hat.com>, Simon Horman <horms@...nel.org>
Cc: llvm@...ts.linux.dev, oe-kbuild-all@...ts.linux.dev,
 LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/4] netlink: Move an assignment for the variable “sk” in __netlink_kernel_create()

…
> url:    https://github.com/intel-lab-lkp/linux/commits/Markus-Elfring/netlink-Improve-exception-handling-in-__netlink_kernel_create/20240101-015025
…
> patch link:    https://lore.kernel.org/r/223a61e9-f826-4f37-b514-ca6ed53b1269%40web.de
…
> All warnings (new ones prefixed by >>):
>
>>> net/netlink/af_netlink.c:2044:6: warning: variable 'sk' is used uninitialized whenever 'if' condition is true [-Wsometimes-uninitialized]
…
>
…
> ^1da177e4c3f41 Linus Torvalds    2005-04-16  2016  struct sock *
> 9f00d9776bc5be Pablo Neira Ayuso 2012-09-08  2017  __netlink_kernel_create(struct net *net, int unit, struct module *module,
> a31f2d17b331db Pablo Neira Ayuso 2012-06-29  2018  			struct netlink_kernel_cfg *cfg)
> ^1da177e4c3f41 Linus Torvalds    2005-04-16  2019  {
> ^1da177e4c3f41 Linus Torvalds    2005-04-16  2020  	struct socket *sock;
> ^1da177e4c3f41 Linus Torvalds    2005-04-16  2021  	struct sock *sk;
…
> 5c398dc8f5a58b Eric Dumazet      2010-10-24  2023  	struct listeners *listeners = NULL;
…
> ^1da177e4c3f41 Linus Torvalds    2005-04-16  2032  	if (sock_create_lite(PF_NETLINK, SOCK_DGRAM, unit, &sock))
> ^1da177e4c3f41 Linus Torvalds    2005-04-16  2033  		return NULL;
…
> 5c398dc8f5a58b Eric Dumazet      2010-10-24  2043  	listeners = kzalloc(sizeof(*listeners) + NLGRPSZ(groups), GFP_KERNEL);
> 4277a083ecd2c8 Patrick McHardy   2006-03-20 @2044  	if (!listeners)
> 90ae404765d263 Markus Elfring    2023-12-31  2045  		goto out_netlink_release_sock;
> 4277a083ecd2c8 Patrick McHardy   2006-03-20  2046
> e547df909ec09d Markus Elfring    2023-12-31  2047  	sk = sock->sk;
> ^1da177e4c3f41 Linus Torvalds    2005-04-16  2048  	sk->sk_data_ready = netlink_data_ready;
…
> 4fdb3bb723db46 Harald Welte      2005-08-09  2075  	netlink_table_ungrab();
> 77247bbb309424 Patrick McHardy   2005-08-14  2076  	return sk;
> 77247bbb309424 Patrick McHardy   2005-08-14  2077
> 4fdb3bb723db46 Harald Welte      2005-08-09  2078  out_sock_release:
> 4277a083ecd2c8 Patrick McHardy   2006-03-20  2079  	kfree(listeners);
> 90ae404765d263 Markus Elfring    2023-12-31  2080  out_netlink_release_sock:
> 9dfbec1fb2bedf Denis V. Lunev    2008-02-29  2081  	netlink_kernel_release(sk);
> 23fe18669e7fda Pavel Emelyanov   2008-01-30  2082  	return NULL;

How do you think about to use the function call “netlink_kernel_release(sock->sk)”?

Regards,
Markus