netdev - Re: [PATCH net-next] unix: Improve locking scheme in unix_show

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Message-ID: <202301141349.PUsDqg8t-lkp@intel.com>
Date:   Sat, 14 Jan 2023 13:30:43 +0800
From:   kernel test robot <lkp@...el.com>
To:     Kirill Tkhai <tkhai@...ru>, davem@...emloft.net,
        edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com,
        kuniyu@...zon.com, netdev@...r.kernel.org
Cc:     llvm@...ts.linux.dev, oe-kbuild-all@...ts.linux.dev
Subject: Re: [PATCH net-next] unix: Improve locking scheme in
 unix_show_fdinfo()

Hi Kirill,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on net-next/master]

url:    https://github.com/intel-lab-lkp/linux/commits/Kirill-Tkhai/unix-Improve-locking-scheme-in-unix_show_fdinfo/20230114-082118
patch link:    https://lore.kernel.org/r/9d951e81-2051-5b67-a394-2cb819e5bf57%40ya.ru
patch subject: [PATCH net-next] unix: Improve locking scheme in unix_show_fdinfo()
config: x86_64-rhel-8.3-rust
compiler: clang version 14.0.6 (https://github.com/llvm/llvm-project f28c006a5895fc0e329fe15fead81e37457cb1d1)
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://github.com/intel-lab-lkp/linux/commit/1c3b5ffa3da1bc362d28489fc860432b09e8a451
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review Kirill-Tkhai/unix-Improve-locking-scheme-in-unix_show_fdinfo/20230114-082118
        git checkout 1c3b5ffa3da1bc362d28489fc860432b09e8a451
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=x86_64 olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash net/unix/

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@...el.com>

All warnings (new ones prefixed by >>):

>> net/unix/af_unix.c:824:12: warning: variable 'nr_fds' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
                   else if (s_state == TCP_LISTEN)
                            ^~~~~~~~~~~~~~~~~~~~~
   net/unix/af_unix.c:827:34: note: uninitialized use occurs here
                   seq_printf(m, "scm_fds: %u\n", nr_fds);
                                                  ^~~~~~
   net/unix/af_unix.c:824:8: note: remove the 'if' if its condition is always true
                   else if (s_state == TCP_LISTEN)
                        ^~~~~~~~~~~~~~~~~~~~~~~~~~
   net/unix/af_unix.c:812:12: note: initialize the variable 'nr_fds' to silence this warning
           int nr_fds;
                     ^
                      = 0
   1 warning generated.


vim +824 net/unix/af_unix.c

   806	
   807	static void unix_show_fdinfo(struct seq_file *m, struct socket *sock)
   808	{
   809		struct sock *sk = sock->sk;
   810		unsigned char s_state;
   811		struct unix_sock *u;
   812		int nr_fds;
   813	
   814		if (sk) {
   815			s_state = READ_ONCE(sk->sk_state);
   816			u = unix_sk(sk);
   817	
   818			/* SOCK_STREAM and SOCK_SEQPACKET sockets never change their
   819			 * sk_state after switching to TCP_ESTABLISHED or TCP_LISTEN.
   820			 * SOCK_DGRAM is ordinary. So, no lock is needed.
   821			 */
   822			if (sock->type == SOCK_DGRAM || s_state == TCP_ESTABLISHED)
   823				nr_fds = atomic_read(&u->scm_stat.nr_fds);
 > 824			else if (s_state == TCP_LISTEN)
   825				nr_fds = unix_count_nr_fds(sk);
   826	
   827			seq_printf(m, "scm_fds: %u\n", nr_fds);
   828		}
   829	}
   830	#else
   831	#define unix_show_fdinfo NULL
   832	#endif
   833	

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests

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