[zanussi-trace:ftrace/synth-fixes-v4 4/5] kernel/trace/trace_events_synth.c:1508:6: warning: variable 'save_argv' is used uninitialized whenever 'if' condition is true

[zanussi-trace:ftrace/synth-fixes-v4 4/5] kernel/trace/trace_events_synth.c:1508:6: warning: variable 'save_argv' is used uninitialized whenever 'if' condition is true

[kernel test robot]

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tree:   https://git.kernel.org/pub/scm/linux/kernel/git/zanussi/linux-trace.git ftrace/synth-fixes-v4
head:   6cb978ea1a56e76f723fb7aee74422b0766db8e9
commit: 10708db9327a6db3e8cdd9639504923e6629ae85 [4/5] tracing: Add a backward-compatibility check for synthetic event creation
config: powerpc-randconfig-r023-20201217 (attached as .config)
compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project cee1e7d14f4628d6174b33640d502bff3b54ae45)
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 powerpc cross compiling tool for clang build
        # apt-get install binutils-powerpc-linux-gnu
        # https://git.kernel.org/pub/scm/linux/kernel/git/zanussi/linux-trace.git/commit/?id=10708db9327a6db3e8cdd9639504923e6629ae85
        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/synth-fixes-v4
        git checkout 10708db9327a6db3e8cdd9639504923e6629ae85
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=powerpc 

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

All warnings (new ones prefixed by >>):

>> kernel/trace/trace_events_synth.c:1508:6: warning: variable 'save_argv' is used uninitialized whenever 'if' condition is true [-Wsometimes-uninitialized]
           if (!argc)
               ^~~~~
   kernel/trace/trace_events_synth.c:1564:12: note: uninitialized use occurs here
           argv_free(save_argv);
                     ^~~~~~~~~
   kernel/trace/trace_events_synth.c:1508:2: note: remove the 'if' if its condition is always false
           if (!argc)
           ^~~~~~~~~~
   kernel/trace/trace_events_synth.c:1496:33: note: initialize the variable 'save_argv' to silence this warning
           char *name, **argv, **save_argv;
                                          ^
                                           = NULL
>> kernel/trace/trace_events_synth.c:1508:6: warning: variable 'buf' is used uninitialized whenever 'if' condition is true [-Wsometimes-uninitialized]
           if (!argc)
               ^~~~~
   kernel/trace/trace_events_synth.c:1566:9: note: uninitialized use occurs here
           return buf;
                  ^~~
   kernel/trace/trace_events_synth.c:1508:2: note: remove the 'if' if its condition is always false
           if (!argc)
           ^~~~~~~~~~
   kernel/trace/trace_events_synth.c:1500:11: note: initialize the variable 'buf' to silence this warning
           char *buf;
                    ^
                     = NULL
   2 warnings generated.


vim +1508 kernel/trace/trace_events_synth.c

  1492	
  1493	static char *insert_semicolons(const char *raw_command)
  1494	{
  1495		int i, argc, consumed = 0, n_fields = 0, semis_added = 0;
  1496		char *name, **argv, **save_argv;
  1497		int ret = -EINVAL;
  1498		struct seq_buf s;
  1499		bool added_semi;
  1500		char *buf;
  1501	
  1502		argc = 0;
  1503	
  1504		argv = argv_split(GFP_KERNEL, raw_command, &argc);
  1505		if (!argv)
  1506			return NULL;
  1507	
> 1508		if (!argc)
  1509			goto out;
  1510	
  1511		name = argv[0];
  1512		save_argv = argv;
  1513		argv++;
  1514		argc--;
  1515	
  1516		buf = kzalloc(MAX_DYNEVENT_CMD_LEN, GFP_KERNEL);
  1517		if (!buf) {
  1518			ret = -ENOMEM;
  1519			goto err;
  1520		}
  1521	
  1522		seq_buf_init(&s, buf, MAX_DYNEVENT_CMD_LEN);
  1523	
  1524		seq_buf_puts(&s, name);
  1525		seq_buf_putc(&s, ' ');
  1526	
  1527		if (name[0] == '\0' || argc < 1)
  1528			goto err;
  1529	
  1530		for (i = 0; i < argc - 1; i++) {
  1531			if (strcmp(argv[i], ";") == 0) {
  1532				seq_buf_puts(&s, " ; ");
  1533				continue;
  1534			}
  1535	
  1536			if (n_fields == SYNTH_FIELDS_MAX)
  1537				goto err;
  1538	
  1539			ret = save_synth_field(argc - i, &argv[i], &consumed,
  1540					       &s, &added_semi);
  1541			if (ret)
  1542				goto err;
  1543	
  1544			if (added_semi)
  1545				semis_added++;
  1546	
  1547			i += consumed - 1;
  1548		}
  1549	
  1550		if (i < argc && strcmp(argv[i], ";") != 0)
  1551			goto err;
  1552	
  1553		if (!semis_added) {
  1554			kfree(buf);
  1555			buf = NULL;
  1556			goto out;
  1557		}
  1558	
  1559		if (WARN_ON_ONCE(!seq_buf_buffer_left(&s)))
  1560			goto err;
  1561	
  1562		buf[s.len] = '\0';
  1563	 out:
  1564		argv_free(save_argv);
  1565	
  1566		return buf;
  1567	 err:
  1568		kfree(buf);
  1569		buf = ERR_PTR(ret);
  1570	
  1571		goto out;
  1572	}
  1573	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org

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