Re: [PATCH 05/12] tracing: kdb: Use tracer_tracing_on/off() instead of setting per CPU disabled

Re: [PATCH 05/12] tracing: kdb: Use tracer_tracing_on/off() instead of setting per CPU disabled

[kernel test robot]

Hi Steven,

kernel test robot noticed the following build warnings:

[auto build test WARNING on trace/for-next]
[also build test WARNING on linus/master v6.15-rc4 next-20250502]
[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#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Steven-Rostedt/tracing-mmiotrace-Remove-reference-to-unused-per-CPU-data-pointer/20250503-050317
base:   https://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace for-next
patch link:    https://lore.kernel.org/r/20250502205348.643055437%40goodmis.org
patch subject: [PATCH 05/12] tracing: kdb: Use tracer_tracing_on/off() instead of setting per CPU disabled
config: arc-randconfig-002-20250503 (https://download.01.org/0day-ci/archive/20250505/202505051213.exaXF8qp-lkp@intel.com/config)
compiler: arc-linux-gcc (GCC) 11.5.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250505/202505051213.exaXF8qp-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202505051213.exaXF8qp-lkp@intel.com/

All warnings (new ones prefixed by >>):

   kernel/trace/trace_kdb.c: In function 'kdb_ftdump':
>> kernel/trace/trace_kdb.c:101:13: warning: unused variable 'cpu' [-Wunused-variable]
     101 |         int cpu;
         |             ^~~


vim +/cpu +101 kernel/trace/trace_kdb.c

955b61e5979847 Jason Wessel     2010-08-05   91  
955b61e5979847 Jason Wessel     2010-08-05   92  /*
955b61e5979847 Jason Wessel     2010-08-05   93   * kdb_ftdump - Dump the ftrace log buffer
955b61e5979847 Jason Wessel     2010-08-05   94   */
955b61e5979847 Jason Wessel     2010-08-05   95  static int kdb_ftdump(int argc, const char **argv)
955b61e5979847 Jason Wessel     2010-08-05   96  {
dbfe67334a1767 Douglas Anderson 2019-03-19   97  	int skip_entries = 0;
19063c776fe745 Jason Wessel     2010-08-05   98  	long cpu_file;
0c10cc2435115c Yuran Pereira    2024-10-28   99  	int err;
03197fc02b3566 Douglas Anderson 2019-03-19  100  	int cnt;
03197fc02b3566 Douglas Anderson 2019-03-19 @101  	int cpu;
955b61e5979847 Jason Wessel     2010-08-05  102  
19063c776fe745 Jason Wessel     2010-08-05  103  	if (argc > 2)
955b61e5979847 Jason Wessel     2010-08-05  104  		return KDB_ARGCOUNT;
955b61e5979847 Jason Wessel     2010-08-05  105  
0c10cc2435115c Yuran Pereira    2024-10-28  106  	if (argc && kstrtoint(argv[1], 0, &skip_entries))
0c10cc2435115c Yuran Pereira    2024-10-28  107  		return KDB_BADINT;
955b61e5979847 Jason Wessel     2010-08-05  108  
19063c776fe745 Jason Wessel     2010-08-05  109  	if (argc == 2) {
0c10cc2435115c Yuran Pereira    2024-10-28  110  		err = kstrtol(argv[2], 0, &cpu_file);
0c10cc2435115c Yuran Pereira    2024-10-28  111  		if (err || cpu_file >= NR_CPUS || cpu_file < 0 ||
19063c776fe745 Jason Wessel     2010-08-05  112  		    !cpu_online(cpu_file))
19063c776fe745 Jason Wessel     2010-08-05  113  			return KDB_BADINT;
19063c776fe745 Jason Wessel     2010-08-05  114  	} else {
ae3b5093ad6004 Steven Rostedt   2013-01-23  115  		cpu_file = RING_BUFFER_ALL_CPUS;
19063c776fe745 Jason Wessel     2010-08-05  116  	}
19063c776fe745 Jason Wessel     2010-08-05  117  
955b61e5979847 Jason Wessel     2010-08-05  118  	kdb_trap_printk++;
03197fc02b3566 Douglas Anderson 2019-03-19  119  
03197fc02b3566 Douglas Anderson 2019-03-19  120  	trace_init_global_iter(&iter);
03197fc02b3566 Douglas Anderson 2019-03-19  121  	iter.buffer_iter = buffer_iter;
03197fc02b3566 Douglas Anderson 2019-03-19  122  
6a4611f6bb763d Steven Rostedt   2025-05-02  123  	tracer_tracing_off(iter.tr);
03197fc02b3566 Douglas Anderson 2019-03-19  124  
03197fc02b3566 Douglas Anderson 2019-03-19  125  	/* A negative skip_entries means skip all but the last entries */
03197fc02b3566 Douglas Anderson 2019-03-19  126  	if (skip_entries < 0) {
03197fc02b3566 Douglas Anderson 2019-03-19  127  		if (cpu_file == RING_BUFFER_ALL_CPUS)
03197fc02b3566 Douglas Anderson 2019-03-19  128  			cnt = trace_total_entries(NULL);
03197fc02b3566 Douglas Anderson 2019-03-19  129  		else
03197fc02b3566 Douglas Anderson 2019-03-19  130  			cnt = trace_total_entries_cpu(NULL, cpu_file);
03197fc02b3566 Douglas Anderson 2019-03-19  131  		skip_entries = max(cnt + skip_entries, 0);
03197fc02b3566 Douglas Anderson 2019-03-19  132  	}
03197fc02b3566 Douglas Anderson 2019-03-19  133  
dbfe67334a1767 Douglas Anderson 2019-03-19  134  	ftrace_dump_buf(skip_entries, cpu_file);
03197fc02b3566 Douglas Anderson 2019-03-19  135  
6a4611f6bb763d Steven Rostedt   2025-05-02  136  	tracer_tracing_on(iter.tr);
03197fc02b3566 Douglas Anderson 2019-03-19  137  
955b61e5979847 Jason Wessel     2010-08-05  138  	kdb_trap_printk--;
955b61e5979847 Jason Wessel     2010-08-05  139  
955b61e5979847 Jason Wessel     2010-08-05  140  	return 0;
955b61e5979847 Jason Wessel     2010-08-05  141  }
955b61e5979847 Jason Wessel     2010-08-05  142  

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki