Re: [PATCH v5] function_graph: Enable funcgraph-args and funcgraph-retaddr to work simultaneously

[kernel test robot <lkp@intel.com>]

Hi Donglin,

kernel test robot noticed the following build warnings:

[auto build test WARNING on v6.18-rc5]
[also build test WARNING on linus/master]
[cannot apply to trace/for-next next-20251113]
[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/Donglin-Peng/function_graph-Enable-funcgraph-args-and-funcgraph-retaddr-to-work-simultaneously/20251113-153332
base:   v6.18-rc5
patch link:    https://lore.kernel.org/r/20251113072938.333657-1-dolinux.peng%40gmail.com
patch subject: [PATCH v5] function_graph: Enable funcgraph-args and funcgraph-retaddr to work simultaneously
config: sparc64-randconfig-001-20251113 (https://download.01.org/0day-ci/archive/20251114/202511140224.loIXI9Us-lkp@intel.com/config)
compiler: clang version 20.1.8 (https://github.com/llvm/llvm-project 87f0227cb60147a26a1eeb4fb06e3b505e9c7261)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251114/202511140224.loIXI9Us-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/202511140224.loIXI9Us-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> kernel/trace/trace_functions_graph.c:146:19: warning: variable 'args_offs' set but not used [-Wunused-but-set-variable]
     146 |         int nr_args = 0, args_offs = 0;
         |                          ^
   kernel/trace/trace_functions_graph.c:169:20: warning: variable 'retaddr' is uninitialized when used here [-Wuninitialized]
     169 |                 entry->args[0] = retaddr;
         |                                  ^~~~~~~
   kernel/trace/trace_functions_graph.c:143:23: note: initialize the variable 'retaddr' to silence this warning
     143 |         unsigned long retaddr;
         |                              ^
         |                               = 0
   2 warnings generated.


vim +/args_offs +146 kernel/trace/trace_functions_graph.c

   132	
   133	static void
   134	print_graph_duration(struct trace_array *tr, unsigned long long duration,
   135			     struct trace_seq *s, u32 flags);
   136	
   137	static int __graph_entry(struct trace_array *tr, struct ftrace_graph_ent *trace,
   138				 unsigned int trace_ctx, struct ftrace_regs *fregs)
   139	{
   140		struct ring_buffer_event *event;
   141		struct trace_buffer *buffer = tr->array_buffer.buffer;
   142		struct ftrace_graph_ent_entry *entry;
   143		unsigned long retaddr;
   144		int size = sizeof(*entry);
   145		int type = TRACE_GRAPH_ENT;
 > 146		int nr_args = 0, args_offs = 0;
   147	
   148		if (IS_ENABLED(CONFIG_FUNCTION_GRAPH_RETADDR) &&
   149			tracer_flags_is_set(TRACE_GRAPH_PRINT_RETADDR)) {
   150			retaddr = ftrace_graph_top_ret_addr(current);
   151			type = TRACE_GRAPH_RETADDR_ENT;
   152			nr_args += 1;
   153		}
   154	
   155		/* If fregs is defined, add FTRACE_REGS_MAX_ARGS long size words */
   156		if (!!fregs)
   157			nr_args += FTRACE_REGS_MAX_ARGS;
   158	
   159		size += nr_args * sizeof(long);
   160		event = trace_buffer_lock_reserve(buffer, type, size, trace_ctx);
   161		if (!event)
   162			return 0;
   163	
   164		entry = ring_buffer_event_data(event);
   165		entry->graph_ent = *trace;
   166	
   167		/* Store the retaddr in args[0] */
   168		if (type == TRACE_GRAPH_RETADDR_ENT) {
   169			entry->args[0] = retaddr;
   170			args_offs += 1;
   171		}
   172	

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