Messages in this thread | | | From | Ian Rogers <> | Date | Wed, 3 Apr 2024 09:01:56 -0700 | Subject | Re: [PATCH 1/1] perf annotate: Initialize 'arch' variable not to trip some -Werror=maybe-uninitialized |
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On Wed, Apr 3, 2024 at 8:16 AM Arnaldo Carvalho de Melo <acme@kernel.org> wrote: > > In some older distros the build is failing due to > -Werror=maybe-uninitialized, in this case we know that this isn't the > case because 'arch' gets initialized by evsel__get_arch(), so just init > it to NULL to silence those cases. > > E.g.: > > 32 17.12 opensuse:15.5 : FAIL gcc version 7.5.0 (SUSE Linux) > util/annotate.c: In function 'hist_entry__get_data_type': > util/annotate.c:2269:15: error: 'arch' may be used uninitialized in this function [-Werror=maybe-uninitialized] > struct arch *arch; > ^~~~ > cc1: all warnings being treated as errors > > 43 7.30 ubuntu:18.04-x-powerpc64el : FAIL gcc version 7.5.0 (Ubuntu 7.5.0-3ubuntu1~18.04) > util/annotate.c: In function 'hist_entry__get_data_type': > util/annotate.c:2351:36: error: 'arch' may be used uninitialized in this function [-Werror=maybe-uninitialized] > if (map__dso(ms->map)->kernel && arch__is(arch, "x86") && > ^~~~~~~~~~~~~~~~~~~~~ > cc1: all warnings being treated as errors > > Cc: Adrian Hunter <adrian.hunter@intel.com> > Cc: Ian Rogers <irogers@google.com> > Cc: Jiri Olsa <jolsa@kernel.org> > Cc: Namhyung Kim <namhyung@kernel.org> > Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This looks fine but I couldn't line up the errors with code in the tree. I was curious why the "maybe-uninitialized" was failing. Perhaps evsel__get_arch should set the out argument to NULL when an error occurs. This fix is also good but may potentially need repeating for other evsel__get_arch cases, so a fix in evsel__get_arch may be preferable.
Reviewed-by: Ian Rogers <irogers@google.com>
Thanks, Ian
> --- > tools/perf/util/annotate.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/tools/perf/util/annotate.c b/tools/perf/util/annotate.c > index b795f27f26024f35..f316e0b65897957a 100644 > --- a/tools/perf/util/annotate.c > +++ b/tools/perf/util/annotate.c > @@ -2266,7 +2266,7 @@ struct annotated_data_type *hist_entry__get_data_type(struct hist_entry *he) > { > struct map_symbol *ms = &he->ms; > struct evsel *evsel = hists_to_evsel(he->hists); > - struct arch *arch; > + struct arch *arch = NULL; > struct disasm_line *dl; > struct annotated_insn_loc loc; > struct annotated_op_loc *op_loc; > -- > 2.44.0 >
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