linux-kernel - Re: [kbuild-all] Re: net/sunrpc/svcsock.c:527:32: warning: Variable 'uninitialized_var' is assigned a value that is never used. [unreadVariable]

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Date:   Thu, 9 Apr 2020 10:38:05 -0400
From:   Chuck Lever <chuck.lever@...cle.com>
To:     Rong Chen <rong.a.chen@...el.com>
Cc:     kbuild test robot <lkp@...el.com>, kbuild-all@...ts.01.org,
        linux-kernel@...r.kernel.org
Subject: Re: [kbuild-all] Re: net/sunrpc/svcsock.c:527:32: warning: Variable
 'uninitialized_var' is assigned a value that is never used. [unreadVariable]



> On Apr 8, 2020, at 11:04 PM, Rong Chen <rong.a.chen@...el.com> wrote:
> 
> 
> 
> On 4/9/20 5:35 AM, Chuck Lever wrote:
>> 
>>> On Apr 8, 2020, at 5:32 PM, kbuild test robot <lkp@...el.com> wrote:
>>> 
>>> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
>>> head:   f5e94d10e4c468357019e5c28d48499f677b284f
>>> commit: da1661b93bf489cdbc8bcea919b165d31b4810bf SUNRPC: Teach server to use xprt_sock_sendmsg for socket sends
>>> date:   3 weeks ago
>>> 
>>> If you fix the issue, kindly add following tag as appropriate
>>> Reported-by: kbuild test robot <lkp@...el.com>
>>> 
>>> 
>>> cppcheck warnings: (new ones prefixed by >>)
>>> 
>>>   net/sunrpc/svcsock.c:405:9: warning: union member 'Anonymous0::all' is never used. [unusedStructMember]
>>>     long  all[SVC_PKTINFO_SPACE / sizeof(long)];
>>>           ^
>>>   net/sunrpc/svcsock.c:518:9: warning: union member 'Anonymous1::all' is never used. [unusedStructMember]
>>>     long  all[SVC_PKTINFO_SPACE / sizeof(long)];
>>>           ^
>>>>> net/sunrpc/svcsock.c:527:32: warning: Variable 'uninitialized_var' is assigned a value that is never used. [unreadVariable]
>>>    unsigned int uninitialized_var(sent);
>>>                                  ^
>>> 
>>> vim +/uninitialized_var +527 net/sunrpc/svcsock.c
>>> 
>>>   504	
>>>   505	/**
>>>   506	 * svc_udp_sendto - Send out a reply on a UDP socket
>>>   507	 * @rqstp: completed svc_rqst
>>>   508	 *
>>>   509	 * Returns the number of bytes sent, or a negative errno.
>>>   510	 */
>>>   511	static int svc_udp_sendto(struct svc_rqst *rqstp)
>>>   512	{
>>>   513		struct svc_xprt *xprt = rqstp->rq_xprt;
>>>   514		struct svc_sock	*svsk = container_of(xprt, struct svc_sock, sk_xprt);
>>>   515		struct xdr_buf *xdr = &rqstp->rq_res;
>>>   516		union {
>>>   517			struct cmsghdr	hdr;
>>>   518			long		all[SVC_PKTINFO_SPACE / sizeof(long)];
>>>   519		} buffer;
>>>   520		struct cmsghdr *cmh = &buffer.hdr;
>>>   521		struct msghdr msg = {
>>>   522			.msg_name	= &rqstp->rq_addr,
>>>   523			.msg_namelen	= rqstp->rq_addrlen,
>>>   524			.msg_control	= cmh,
>>>   525			.msg_controllen	= sizeof(buffer),
>>>   526		};
>>>> 527		unsigned int uninitialized_var(sent);
>>>   528		int err;
>>>   529	
>>>   530		svc_set_cmsg_data(rqstp, cmh);
>>>   531	
>>>   532		err = xprt_sock_sendmsg(svsk->sk_sock, &msg, xdr, 0, 0, &sent);
>>>   533		xdr_free_bvec(xdr);
>>>   534		if (err == -ECONNREFUSED) {
>>>   535			/* ICMP error on earlier request. */
>>>   536			err = xprt_sock_sendmsg(svsk->sk_sock, &msg, xdr, 0, 0, &sent);
>>>   537			xdr_free_bvec(xdr);
>>>   538		}
>>>   539		if (err < 0)
>>>   540			return err;
>>>   541		return sent;
>> Wha? "sent" is used right here. Can someone explain this warning?
> 
> Hi Chuck,
> 
> Sorry for the inconvenience, it should be a false warning,
> It's every odd that removing uninitialized_var can silence this warning.

Rong, thanks for your response! I will leave the code as-is, then.


> Best Regards,
> Rong Chen
> 
>> 
>> 
>>>   542	}
>>>   543	
>>> 
>>> ---
>>> 0-DAY CI Kernel Test Service, Intel Corporation
>>> https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
>> --
>> Chuck Lever
>> 
>> 
>> _______________________________________________
>> kbuild-all mailing list -- kbuild-all@...ts.01.org
>> To unsubscribe send an email to kbuild-all-leave@...ts.01.org

--
Chuck Lever