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/c... 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(a)intel.com&gt; All warnings (new ones prefixed by >>): 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 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 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