linux-kernel - Re: [PATCH] net/smc: fix TCP fallback socket release

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Date:   Mon, 17 Dec 2018 13:02:18 +0800
From:   kbuild test robot <lkp@...el.com>
To:     Myungho Jung <mhjungk@...il.com>
Cc:     kbuild-all@...org, Ursula Braun <ubraun@...ux.ibm.com>,
        "David S. Miller" <davem@...emloft.net>,
        linux-s390@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] net/smc: fix TCP fallback socket release

Hi Myungho,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on net-next/master]
[also build test WARNING on v4.20-rc7 next-20181214]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Myungho-Jung/net-smc-fix-TCP-fallback-socket-release/20181217-122513
config: x86_64-randconfig-x015-201850 (attached as .config)
compiler: gcc-7 (Debian 7.3.0-1) 7.3.0
reproduce:
        # save the attached .config to linux build tree
        make ARCH=x86_64 

Note: it may well be a FALSE warning. FWIW you are at least aware of it now.
http://gcc.gnu.org/wiki/Better_Uninitialized_Warnings

All warnings (new ones prefixed by >>):

   net/smc/af_smc.c: In function 'smc_tcp_listen_work':
>> net/smc/af_smc.c:1318:6: warning: 'rc' may be used uninitialized in this function [-Wmaybe-uninitialized]
      if (rc)
         ^

vim +/rc +1318 net/smc/af_smc.c

a046d57d Ursula Braun  2017-01-09  1306  
a046d57d Ursula Braun  2017-01-09  1307  static void smc_tcp_listen_work(struct work_struct *work)
a046d57d Ursula Braun  2017-01-09  1308  {
a046d57d Ursula Braun  2017-01-09  1309  	struct smc_sock *lsmc = container_of(work, struct smc_sock,
a046d57d Ursula Braun  2017-01-09  1310  					     tcp_listen_work);
3163c507 Ursula Braun  2018-01-24  1311  	struct sock *lsk = &lsmc->sk;
a046d57d Ursula Braun  2017-01-09  1312  	struct smc_sock *new_smc;
a046d57d Ursula Braun  2017-01-09  1313  	int rc = 0;
a046d57d Ursula Braun  2017-01-09  1314  
3163c507 Ursula Braun  2018-01-24  1315  	lock_sock(lsk);
3163c507 Ursula Braun  2018-01-24  1316  	while (lsk->sk_state == SMC_LISTEN) {
a046d57d Ursula Braun  2017-01-09  1317  		rc = smc_clcsock_accept(lsmc, &new_smc);
a046d57d Ursula Braun  2017-01-09 @1318  		if (rc)
a046d57d Ursula Braun  2017-01-09  1319  			goto out;
a046d57d Ursula Braun  2017-01-09  1320  		if (!new_smc)
a046d57d Ursula Braun  2017-01-09  1321  			continue;
a046d57d Ursula Braun  2017-01-09  1322  
a046d57d Ursula Braun  2017-01-09  1323  		new_smc->listen_smc = lsmc;
ee9dfbef Ursula Braun  2018-04-26  1324  		new_smc->use_fallback = lsmc->use_fallback;
603cc149 Karsten Graul 2018-07-25  1325  		new_smc->fallback_rsn = lsmc->fallback_rsn;
3163c507 Ursula Braun  2018-01-24  1326  		sock_hold(lsk); /* sock_put in smc_listen_work */
a046d57d Ursula Braun  2017-01-09  1327  		INIT_WORK(&new_smc->smc_listen_work, smc_listen_work);
a046d57d Ursula Braun  2017-01-09  1328  		smc_copy_sock_settings_to_smc(new_smc);
bd58c7e0 Ursula Braun  2018-08-08  1329  		new_smc->sk.sk_sndbuf = lsmc->sk.sk_sndbuf;
bd58c7e0 Ursula Braun  2018-08-08  1330  		new_smc->sk.sk_rcvbuf = lsmc->sk.sk_rcvbuf;
51f1de79 Ursula Braun  2018-01-26  1331  		sock_hold(&new_smc->sk); /* sock_put in passive closing */
51f1de79 Ursula Braun  2018-01-26  1332  		if (!schedule_work(&new_smc->smc_listen_work))
51f1de79 Ursula Braun  2018-01-26  1333  			sock_put(&new_smc->sk);
a046d57d Ursula Braun  2017-01-09  1334  	}
a046d57d Ursula Braun  2017-01-09  1335  
a046d57d Ursula Braun  2017-01-09  1336  out:
3163c507 Ursula Braun  2018-01-24  1337  	release_sock(lsk);
51f1de79 Ursula Braun  2018-01-26  1338  	sock_put(&lsmc->sk); /* sock_hold in smc_listen */
a046d57d Ursula Braun  2017-01-09  1339  }
a046d57d Ursula Braun  2017-01-09  1340  

:::::: The code at line 1318 was first introduced by commit
:::::: a046d57da19f812216f393e7c535f5858f793ac3 smc: CLC handshake (incl. preparation steps)

:::::: TO: Ursula Braun <ubraun@...ux.vnet.ibm.com>
:::::: CC: David S. Miller <davem@...emloft.net>

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