linux-kernel - [zanussi-trace:ftrace/masami-hitcount-v0 1/3] kernel/trace/trace_events_hist.c:4354:9: warning: variable 'n_hitcount' is uninitialized when used here

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Message-ID: <202208260943.kWLI2lN6-lkp@intel.com>
Date:   Fri, 26 Aug 2022 09:44:51 +0800
From:   kernel test robot <lkp@...el.com>
To:     Tom Zanussi <zanussi@...nel.org>
Cc:     llvm@...ts.linux.dev, kbuild-all@...ts.01.org,
        linux-kernel@...r.kernel.org
Subject: [zanussi-trace:ftrace/masami-hitcount-v0 1/3]
 kernel/trace/trace_events_hist.c:4354:9: warning: variable 'n_hitcount' is
 uninitialized when used here

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/zanussi/linux-trace.git ftrace/masami-hitcount-v0
head:   886fe9b6098eddb9d298e8a3f07bbea61acdac16
commit: 2b0a73549f8fb4115c06639c75a4b7abd7825aaa [1/3] tracing: Allow multiple hitcount values in histograms
config: x86_64-randconfig-a005 (https://download.01.org/0day-ci/archive/20220826/202208260943.kWLI2lN6-lkp@intel.com/config)
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://git.kernel.org/pub/scm/linux/kernel/git/zanussi/linux-trace.git/commit/?id=2b0a73549f8fb4115c06639c75a4b7abd7825aaa
        git remote add zanussi-trace https://git.kernel.org/pub/scm/linux/kernel/git/zanussi/linux-trace.git
        git fetch --no-tags zanussi-trace ftrace/masami-hitcount-v0
        git checkout 2b0a73549f8fb4115c06639c75a4b7abd7825aaa
        # 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 SHELL=/bin/bash kernel/trace/

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 >>):

>> kernel/trace/trace_events_hist.c:4354:9: warning: variable 'n_hitcount' is uninitialized when used here [-Wuninitialized]
                           if (!n_hitcount++)
                                ^~~~~~~~~~
   kernel/trace/trace_events_hist.c:4335:35: note: initialize the variable 'n_hitcount' to silence this warning
           unsigned int i, j = 1, n_hitcount;
                                            ^
                                             = 0
   1 warning generated.


vim +/n_hitcount +4354 kernel/trace/trace_events_hist.c

  4331	
  4332	static int create_val_fields(struct hist_trigger_data *hist_data,
  4333				     struct trace_event_file *file)
  4334	{
  4335		unsigned int i, j = 1, n_hitcount;
  4336		char *fields_str, *field_str;
  4337		int ret;
  4338	
  4339		ret = create_hitcount_val(hist_data);
  4340		if (ret)
  4341			goto out;
  4342	
  4343		fields_str = hist_data->attrs->vals_str;
  4344		if (!fields_str)
  4345			goto out;
  4346	
  4347		for (i = 0, j = 1; i < TRACING_MAP_VALS_MAX &&
  4348			     j < TRACING_MAP_VALS_MAX; i++) {
  4349			field_str = strsep(&fields_str, ",");
  4350			if (!field_str)
  4351				break;
  4352	
  4353			if (strcmp(field_str, "hitcount") == 0) {
> 4354				if (!n_hitcount++)
  4355					continue;
  4356			}
  4357	
  4358			ret = create_val_field(hist_data, j++, file, field_str);
  4359			if (ret)
  4360				goto out;
  4361		}
  4362	
  4363		if (fields_str && (strcmp(fields_str, "hitcount") != 0))
  4364			ret = -EINVAL;
  4365	 out:
  4366		return ret;
  4367	}
  4368	

-- 
0-DAY CI Kernel Test Service
https://01.org/lkp