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charset=us-ascii Content-Disposition: inline In-Reply-To: <20240319101000.4dbe0cc5@gandalf.local.home> On Tue, Mar 19, 2024 at 10:10:00AM -0400, Steven Rostedt wrote: > On Tue, 19 Mar 2024 10:19:09 +0300 > Dan Carpenter wrote: > > > Hello Masami Hiramatsu (Google), > > > > Commit 25f00e40ce79 ("tracing/probes: Support $argN in return probe > > (kprobe and fprobe)") from Mar 4, 2024 (linux-next), leads to the > > following Smatch static checker warning: > > > > kernel/trace/trace_probe.c:856 store_trace_entry_data() > > error: uninitialized symbol 'val'. > > > > kernel/trace/trace_probe.c > > 846 return; > > 847 > > 848 for (i = 0; i < earg->size; i++) { > > 849 struct fetch_insn *code = &earg->code[i]; > > 850 > > 851 switch (code->op) { > > 852 case FETCH_OP_ARG: > > 853 val = regs_get_kernel_argument(regs, code->param); > > 854 break; > > 855 case FETCH_OP_ST_EDATA: > > --> 856 *(unsigned long *)((unsigned long)edata + code->offset) = val; > > > > Probably the earg->code[i] always has FETCH_OP_ARG before > > FETCH_OP_ST_EDATA but Smatch isn't smart enough to figure that out... > > Looks that way: > > case FETCH_OP_END: > earg->code[i].op = FETCH_OP_ARG; > earg->code[i].param = argnum; > earg->code[i + 1].op = FETCH_OP_ST_EDATA; > earg->code[i + 1].offset = offset; > return offset; > > But probably should still initialize val to zero or have a WARN_ON() if > that doesn't happen. > Most people use the GCC extension to initialize everything to zero so initializing to zero really has zero cost. I always recomend people to do it. regards, dan carpenter