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Date: Wed, 20 Mar 2024 12:32:50 -0300
From: Arnaldo Carvalho de Melo <acme@kernel.org>
To: Ian Rogers <irogers@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@redhat.com>,
	Namhyung Kim <namhyung@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Jiri Olsa <jolsa@kernel.org>,
	Adrian Hunter <adrian.hunter@intel.com>,
	linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 1/2] perf: Suggest inbuilt commands for unknown command
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On Wed, Mar 20, 2024 at 12:20:20PM -0300, Arnaldo Carvalho de Melo wrote:
> On Wed, Mar 20, 2024 at 08:12:56AM -0700, Ian Rogers wrote:
> > Ah, the change:
> > 
> > -               static int done_help;
> > +               int done_help;
> > 
> > created an uninitialized use. Compiler warning/sanitizers? Anyway,
> > done_help needs hoisting out of the loop and initializing to zero, or
> > being made static again (ugh).
> 
> ⬢[acme@toolbox perf-tools-next]$ git diff
> diff --git a/tools/perf/perf.c b/tools/perf/perf.c
> index c719e6ccd9e27778..f9532b20e87cbf05 100644
> --- a/tools/perf/perf.c
> +++ b/tools/perf/perf.c
> @@ -459,7 +459,7 @@ static int libperf_print(enum libperf_print_level level,
>  
>  int main(int argc, const char **argv)
>  {
> -       int err;
> +       int err, done_help = 0;
>         const char *cmd;
>         char sbuf[STRERR_BUFSIZE];
>  
> @@ -558,8 +558,6 @@ int main(int argc, const char **argv)
>         pthread__block_sigwinch();
>  
>         while (1) {
> -               int done_help;
> -
>                 run_argv(&argc, &argv);
>  
>                 if (errno != ENOENT)
> ⬢[acme@toolbox perf-tools-next]$ perf raccord
>   Fatal: Out of memory, realloc failed
> ⬢[acme@toolbox perf-tools-next]$
> 
> Then:
> 
> diff --git a/tools/perf/perf.c b/tools/perf/perf.c
> index c719e6ccd9e27778..54f62aa6612bc290 100644
> --- a/tools/perf/perf.c
> +++ b/tools/perf/perf.c
> @@ -558,7 +558,7 @@ int main(int argc, const char **argv)
>         pthread__block_sigwinch();
>  
>         while (1) {
> -               int done_help;
> +               static int done_help;
>  
>                 run_argv(&argc, &argv);
>  
> ⬢[acme@toolbox perf-tools-next]$ perf raccord
>   Fatal: Out of memory, realloc failed
> ⬢[acme@toolbox perf-tools-next]$

That main_cmds variable is uninitialized, which ends up making
add_cmdname() to explode, are you sure this is working on your side?

Further clarifying, this is without considering the second patch, I
haven't got to it yet, from what I recall from the description it
shouldn't matter tho.

- Arnaldo

⬢[acme@toolbox perf-tools-next]$ git diff
diff --git a/tools/perf/perf.c b/tools/perf/perf.c
index c719e6ccd9e27778..164b3c78baff4204 100644
--- a/tools/perf/perf.c
+++ b/tools/perf/perf.c
@@ -558,7 +558,7 @@ int main(int argc, const char **argv)
        pthread__block_sigwinch();
 
        while (1) {
-               int done_help;
+               static int done_help;
 
                run_argv(&argc, &argv);
 
@@ -566,7 +566,7 @@ int main(int argc, const char **argv)
                        break;
 
                if (!done_help) {
-                       struct cmdnames main_cmds;
+                       struct cmdnames main_cmds = { 0, };
 
                        for (unsigned int i = 0; i < ARRAY_SIZE(commands); i++) {
                                add_cmdname(&main_cmds,
⬢[acme@toolbox perf-tools-next]$ perf raccord
perf: 'raccord' is not a perf-command. See 'perf --help'.
⬢[acme@toolbox perf-tools-next]$