[PATCH 1/1] perf annotate: Initialize 'arch' variable not to trip some -Werror=maybe-uninitialized

[PATCH 1/1] perf annotate: Initialize 'arch' variable not to trip some -Werror=maybe-uninitialized

[Arnaldo Carvalho de Melo]

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>
---
 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

Re: [PATCH 1/1] perf annotate: Initialize 'arch' variable not to trip some -Werror=maybe-uninitialized

[Ian Rogers]

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
>

Re: [PATCH 1/1] perf annotate: Initialize 'arch' variable not to trip some -Werror=maybe-uninitialized

[Arnaldo Carvalho de Melo]

On Wed, Apr 03, 2024 at 09:01:56AM -0700, Ian Rogers wrote:
> 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>

Trying with this on top, i.e. what you suggests:

From 70e6fd996ce7f9c9adbb30640ed666025bf6f1e4 Mon Sep 17 00:00:00 2001
From: Arnaldo Carvalho de Melo <acme@redhat.com>
Date: Wed, 3 Apr 2024 16:49:54 -0300
Subject: [PATCH 1/1] WIP

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/util/annotate.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/tools/perf/util/annotate.c b/tools/perf/util/annotate.c
index f316e0b65897957a..35235147b111e788 100644
--- a/tools/perf/util/annotate.c
+++ b/tools/perf/util/annotate.c
@@ -838,8 +838,10 @@ static int evsel__get_arch(struct evsel *evsel, struct arch **parch)
 	struct arch *arch;
 	int err;
 
-	if (!arch_name)
+	if (!arch_name) {
+		*parch = NULL;
 		return errno;
+	}
 
 	*parch = arch = arch__find(arch_name);
 	if (arch == NULL) {
@@ -2266,7 +2268,7 @@ 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 = NULL;
+	struct arch *arch;
 	struct disasm_line *dl;
 	struct annotated_insn_loc loc;
 	struct annotated_op_loc *op_loc;
-- 
2.44.0

Re: [PATCH 1/1] perf annotate: Initialize 'arch' variable not to trip some -Werror=maybe-uninitialized

[Namhyung Kim]

On Wed, Apr 3, 2024 at 12:52 PM Arnaldo Carvalho de Melo
<acme@kernel.org> wrote:
>
> On Wed, Apr 03, 2024 at 09:01:56AM -0700, Ian Rogers wrote:
> > 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>
>
> Trying with this on top, i.e. what you suggests:
>
> From 70e6fd996ce7f9c9adbb30640ed666025bf6f1e4 Mon Sep 17 00:00:00 2001
> From: Arnaldo Carvalho de Melo <acme@redhat.com>
> Date: Wed, 3 Apr 2024 16:49:54 -0300
> Subject: [PATCH 1/1] WIP
>
> Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Acked-by: Namhyung Kim <namhyung@kernel.org>

Thanks,
Namhyung


> ---
>  tools/perf/util/annotate.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/tools/perf/util/annotate.c b/tools/perf/util/annotate.c
> index f316e0b65897957a..35235147b111e788 100644
> --- a/tools/perf/util/annotate.c
> +++ b/tools/perf/util/annotate.c
> @@ -838,8 +838,10 @@ static int evsel__get_arch(struct evsel *evsel, struct arch **parch)
>         struct arch *arch;
>         int err;
>
> -       if (!arch_name)
> +       if (!arch_name) {
> +               *parch = NULL;
>                 return errno;
> +       }
>
>         *parch = arch = arch__find(arch_name);
>         if (arch == NULL) {
> @@ -2266,7 +2268,7 @@ 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 = NULL;
> +       struct arch *arch;
>         struct disasm_line *dl;
>         struct annotated_insn_loc loc;
>         struct annotated_op_loc *op_loc;
> --
> 2.44.0
>

Re: [PATCH 1/1] perf annotate: Initialize 'arch' variable not to trip some -Werror=maybe-uninitialized

[Arnaldo Carvalho de Melo]

On Wed, Apr 03, 2024 at 09:01:56AM -0700, Ian Rogers wrote:
> 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>

Yeah, your suggestion is better and I just tested, satisfies the
compilers that were emitting this warning.

I stamped a:

Suggested-by: Ian Rogers <irogers@google.com>

and kept your Reviewed-by, ok?

- Arnaldo

Re: [PATCH 1/1] perf annotate: Initialize 'arch' variable not to trip some -Werror=maybe-uninitialized

[Ian Rogers]

On Wed, Apr 3, 2024 at 2:03 PM Arnaldo Carvalho de Melo <acme@kernel.org> wrote:
>
> On Wed, Apr 03, 2024 at 09:01:56AM -0700, Ian Rogers wrote:
> > 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>
>
> Yeah, your suggestion is better and I just tested, satisfies the
> compilers that were emitting this warning.
>
> I stamped a:
>
> Suggested-by: Ian Rogers <irogers@google.com>
>
> and kept your Reviewed-by, ok?

Sure :-)

Thanks,
Ian

> - Arnaldo