Re: [PATCH] scsi: libfc: Fix passing zero to 'PTR_ERR' warning

[kernel test robot]

Hi YueHaibing,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on mkp-scsi/for-next]
[also build test WARNING on scsi/for-next v5.9-rc1 next-20200818]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/YueHaibing/scsi-libfc-Fix-passing-zero-to-PTR_ERR-warning/20200818-194521
base:   https://git.kernel.org/pub/scm/linux/kernel/git/mkp/scsi.git for-next
config: x86_64-randconfig-a002-20200818 (attached as .config)
compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project 790878f291fa5dc58a1c560cb6cc76fd1bfd1c5a)
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
        # install x86_64 cross compiling tool for clang build
        # apt-get install binutils-x86-64-linux-gnu
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=x86_64 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@xxxxxxxxx>

All warnings (new ones prefixed by >>):

>> drivers/scsi/libfc/fc_disc.c:365:6: warning: variable 'err' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
           if (lport->tt.elsct_send(lport, 0, fp,
               ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   drivers/scsi/libfc/fc_disc.c:371:30: note: uninitialized use occurs here
           fc_disc_error(disc, ERR_PTR(err));
                                       ^~~
   drivers/scsi/libfc/fc_disc.c:365:2: note: remove the 'if' if its condition is always true
           if (lport->tt.elsct_send(lport, 0, fp,
           ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   drivers/scsi/libfc/fc_disc.c:346:9: note: initialize the variable 'err' to silence this warning
           int err;
                  ^
                   = 0
   1 warning generated.

# https://github.com/0day-ci/linux/commit/c22a185df6f9701ac244e7f2ec1ba38e27177aec
git remote add linux-review https://github.com/0day-ci/linux
git fetch --no-tags linux-review YueHaibing/scsi-libfc-Fix-passing-zero-to-PTR_ERR-warning/20200818-194521
git checkout c22a185df6f9701ac244e7f2ec1ba38e27177aec
vim +365 drivers/scsi/libfc/fc_disc.c

42e9a92fe6a909 Robert Love     2008-12-09  337  
42e9a92fe6a909 Robert Love     2008-12-09  338  /**
34f42a070fc98f Robert Love     2009-02-27  339   * fc_disc_gpn_ft_req() - Send Get Port Names by FC-4 type (GPN_FT) request
b1987c884585a6 Lee Jones       2020-07-07  340   * @disc: The discovery context
42e9a92fe6a909 Robert Love     2008-12-09  341   */
42e9a92fe6a909 Robert Love     2008-12-09  342  static void fc_disc_gpn_ft_req(struct fc_disc *disc)
42e9a92fe6a909 Robert Love     2008-12-09  343  {
42e9a92fe6a909 Robert Love     2008-12-09  344  	struct fc_frame *fp;
0685230c59b548 Joe Eykholt     2010-07-20  345  	struct fc_lport *lport = fc_disc_lport(disc);
c22a185df6f970 YueHaibing      2020-08-18  346  	int err;
42e9a92fe6a909 Robert Love     2008-12-09  347  
ee35624e1e4e4e Hannes Reinecke 2018-07-04  348  	lockdep_assert_held(&disc->disc_mutex);
ee35624e1e4e4e Hannes Reinecke 2018-07-04  349  
42e9a92fe6a909 Robert Love     2008-12-09  350  	WARN_ON(!fc_lport_test_ready(lport));
42e9a92fe6a909 Robert Love     2008-12-09  351  
42e9a92fe6a909 Robert Love     2008-12-09  352  	disc->pending = 1;
42e9a92fe6a909 Robert Love     2008-12-09  353  	disc->requested = 0;
42e9a92fe6a909 Robert Love     2008-12-09  354  
42e9a92fe6a909 Robert Love     2008-12-09  355  	disc->buf_len = 0;
42e9a92fe6a909 Robert Love     2008-12-09  356  	disc->seq_count = 0;
42e9a92fe6a909 Robert Love     2008-12-09  357  	fp = fc_frame_alloc(lport,
42e9a92fe6a909 Robert Love     2008-12-09  358  			    sizeof(struct fc_ct_hdr) +
42e9a92fe6a909 Robert Love     2008-12-09  359  			    sizeof(struct fc_ns_gid_ft));
c22a185df6f970 YueHaibing      2020-08-18  360  	if (!fp) {
c22a185df6f970 YueHaibing      2020-08-18  361  		err = -ENOMEM;
42e9a92fe6a909 Robert Love     2008-12-09  362  		goto err;
c22a185df6f970 YueHaibing      2020-08-18  363  	}
42e9a92fe6a909 Robert Love     2008-12-09  364  
a46f327aa5caf2 Joe Eykholt     2009-08-25 @365  	if (lport->tt.elsct_send(lport, 0, fp,
42e9a92fe6a909 Robert Love     2008-12-09  366  				 FC_NS_GPN_FT,
42e9a92fe6a909 Robert Love     2008-12-09  367  				 fc_disc_gpn_ft_resp,
b94f8951bf2566 Joe Eykholt     2009-11-03  368  				 disc, 3 * lport->r_a_tov))
42e9a92fe6a909 Robert Love     2008-12-09  369  		return;
42e9a92fe6a909 Robert Love     2008-12-09  370  err:
c22a185df6f970 YueHaibing      2020-08-18  371  	fc_disc_error(disc, ERR_PTR(err));
42e9a92fe6a909 Robert Love     2008-12-09  372  }
42e9a92fe6a909 Robert Love     2008-12-09  373  

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