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[PATCH 2/4] perf ftrace: Factor out check_ftrace_capable()

Namhyung Kim posted 4 patches 1 year, 6 months ago
[PATCH 2/4] perf ftrace: Factor out check_ftrace_capable()
Posted by Namhyung Kim 1 year, 6 months ago 
The check is a common part of the ftrace commands, let's move it out.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
---
 tools/perf/builtin-ftrace.c | 44 +++++++++++++++++--------------------
 1 file changed, 20 insertions(+), 24 deletions(-)

diff --git a/tools/perf/builtin-ftrace.c b/tools/perf/builtin-ftrace.c
index 33c52ebda2fd..978608ecd89c 100644
--- a/tools/perf/builtin-ftrace.c
+++ b/tools/perf/builtin-ftrace.c
@@ -59,6 +59,22 @@ static void ftrace__workload_exec_failed_signal(int signo __maybe_unused,
 	done = true;
 }
 
+static int check_ftrace_capable(void)
+{
+	if (!(perf_cap__capable(CAP_PERFMON) ||
+	      perf_cap__capable(CAP_SYS_ADMIN))) {
+		pr_err("ftrace only works for %s!\n",
+#ifdef HAVE_LIBCAP_SUPPORT
+		"users with the CAP_PERFMON or CAP_SYS_ADMIN capability"
+#else
+		"root"
+#endif
+		);
+		return -1;
+	}
+	return 0;
+}
+
 static int __write_tracing_file(const char *name, const char *val, bool append)
 {
 	char *file;
@@ -586,18 +602,6 @@ static int __cmd_ftrace(struct perf_ftrace *ftrace)
 		.events = POLLIN,
 	};
 
-	if (!(perf_cap__capable(CAP_PERFMON) ||
-	      perf_cap__capable(CAP_SYS_ADMIN))) {
-		pr_err("ftrace only works for %s!\n",
-#ifdef HAVE_LIBCAP_SUPPORT
-		"users with the CAP_PERFMON or CAP_SYS_ADMIN capability"
-#else
-		"root"
-#endif
-		);
-		return -1;
-	}
-
 	select_tracer(ftrace);
 
 	if (reset_tracing_files(ftrace) < 0) {
@@ -902,18 +906,6 @@ static int __cmd_latency(struct perf_ftrace *ftrace)
 	};
 	int buckets[NUM_BUCKET] = { };
 
-	if (!(perf_cap__capable(CAP_PERFMON) ||
-	      perf_cap__capable(CAP_SYS_ADMIN))) {
-		pr_err("ftrace only works for %s!\n",
-#ifdef HAVE_LIBCAP_SUPPORT
-		"users with the CAP_PERFMON or CAP_SYS_ADMIN capability"
-#else
-		"root"
-#endif
-		);
-		return -1;
-	}
-
 	trace_fd = prepare_func_latency(ftrace);
 	if (trace_fd < 0)
 		goto out;
@@ -1220,6 +1212,10 @@ int cmd_ftrace(int argc, const char **argv)
 	signal(SIGCHLD, sig_handler);
 	signal(SIGPIPE, sig_handler);
 
+	ret = check_ftrace_capable();
+	if (ret < 0)
+		return -1;
+
 	ret = perf_config(perf_ftrace_config, &ftrace);
 	if (ret < 0)
 		return -1;
-- 
2.46.0.rc1.232.g9752f9e123-goog
Re: [PATCH 2/4] perf ftrace: Factor out check_ftrace_capable()
Posted by Ian Rogers 1 year, 6 months ago 
On Sun, Jul 28, 2024 at 5:41 PM Namhyung Kim <namhyung@kernel.org> wrote:
>
> The check is a common part of the ftrace commands, let's move it out.
>
> Signed-off-by: Namhyung Kim <namhyung@kernel.org>

The whole ifdefs and perf_cap__capable seemed wrong, not least as we'd
like the error message to be accurate not just when libcap is present,
so I sent out;
https://lore.kernel.org/lkml/20240729181931.2870851-1-irogers@google.com/
which I think can supersede this.

Thanks,
Ian

> ---
>  tools/perf/builtin-ftrace.c | 44 +++++++++++++++++--------------------
>  1 file changed, 20 insertions(+), 24 deletions(-)
>
> diff --git a/tools/perf/builtin-ftrace.c b/tools/perf/builtin-ftrace.c
> index 33c52ebda2fd..978608ecd89c 100644
> --- a/tools/perf/builtin-ftrace.c
> +++ b/tools/perf/builtin-ftrace.c
> @@ -59,6 +59,22 @@ static void ftrace__workload_exec_failed_signal(int signo __maybe_unused,
>         done = true;
>  }
>
> +static int check_ftrace_capable(void)
> +{
> +       if (!(perf_cap__capable(CAP_PERFMON) ||
> +             perf_cap__capable(CAP_SYS_ADMIN))) {
> +               pr_err("ftrace only works for %s!\n",
> +#ifdef HAVE_LIBCAP_SUPPORT
> +               "users with the CAP_PERFMON or CAP_SYS_ADMIN capability"
> +#else
> +               "root"
> +#endif
> +               );
> +               return -1;
> +       }
> +       return 0;
> +}
> +
>  static int __write_tracing_file(const char *name, const char *val, bool append)
>  {
>         char *file;
> @@ -586,18 +602,6 @@ static int __cmd_ftrace(struct perf_ftrace *ftrace)
>                 .events = POLLIN,
>         };
>
> -       if (!(perf_cap__capable(CAP_PERFMON) ||
> -             perf_cap__capable(CAP_SYS_ADMIN))) {
> -               pr_err("ftrace only works for %s!\n",
> -#ifdef HAVE_LIBCAP_SUPPORT
> -               "users with the CAP_PERFMON or CAP_SYS_ADMIN capability"
> -#else
> -               "root"
> -#endif
> -               );
> -               return -1;
> -       }
> -
>         select_tracer(ftrace);
>
>         if (reset_tracing_files(ftrace) < 0) {
> @@ -902,18 +906,6 @@ static int __cmd_latency(struct perf_ftrace *ftrace)
>         };
>         int buckets[NUM_BUCKET] = { };
>
> -       if (!(perf_cap__capable(CAP_PERFMON) ||
> -             perf_cap__capable(CAP_SYS_ADMIN))) {
> -               pr_err("ftrace only works for %s!\n",
> -#ifdef HAVE_LIBCAP_SUPPORT
> -               "users with the CAP_PERFMON or CAP_SYS_ADMIN capability"
> -#else
> -               "root"
> -#endif
> -               );
> -               return -1;
> -       }
> -
>         trace_fd = prepare_func_latency(ftrace);
>         if (trace_fd < 0)
>                 goto out;
> @@ -1220,6 +1212,10 @@ int cmd_ftrace(int argc, const char **argv)
>         signal(SIGCHLD, sig_handler);
>         signal(SIGPIPE, sig_handler);
>
> +       ret = check_ftrace_capable();
> +       if (ret < 0)
> +               return -1;
> +
>         ret = perf_config(perf_ftrace_config, &ftrace);
>         if (ret < 0)
>                 return -1;
> --
> 2.46.0.rc1.232.g9752f9e123-goog
>
Re: [PATCH 2/4] perf ftrace: Factor out check_ftrace_capable()
Posted by Namhyung Kim 1 year, 6 months ago 
Hi Ian,

On Mon, Jul 29, 2024 at 11:23 AM Ian Rogers <irogers@google.com> wrote:
>
> On Sun, Jul 28, 2024 at 5:41 PM Namhyung Kim <namhyung@kernel.org> wrote:
> >
> > The check is a common part of the ftrace commands, let's move it out.
> >
> > Signed-off-by: Namhyung Kim <namhyung@kernel.org>
>
> The whole ifdefs and perf_cap__capable seemed wrong, not least as we'd
> like the error message to be accurate not just when libcap is present,
> so I sent out;
> https://lore.kernel.org/lkml/20240729181931.2870851-1-irogers@google.com/
> which I think can supersede this.

Thanks for the change!  I'll reply to the patch.
Namhyung

>
> > ---
> >  tools/perf/builtin-ftrace.c | 44 +++++++++++++++++--------------------
> >  1 file changed, 20 insertions(+), 24 deletions(-)
> >
> > diff --git a/tools/perf/builtin-ftrace.c b/tools/perf/builtin-ftrace.c
> > index 33c52ebda2fd..978608ecd89c 100644
> > --- a/tools/perf/builtin-ftrace.c
> > +++ b/tools/perf/builtin-ftrace.c
> > @@ -59,6 +59,22 @@ static void ftrace__workload_exec_failed_signal(int signo __maybe_unused,
> >         done = true;
> >  }
> >
> > +static int check_ftrace_capable(void)
> > +{
> > +       if (!(perf_cap__capable(CAP_PERFMON) ||
> > +             perf_cap__capable(CAP_SYS_ADMIN))) {
> > +               pr_err("ftrace only works for %s!\n",
> > +#ifdef HAVE_LIBCAP_SUPPORT
> > +               "users with the CAP_PERFMON or CAP_SYS_ADMIN capability"
> > +#else
> > +               "root"
> > +#endif
> > +               );
> > +               return -1;
> > +       }
> > +       return 0;
> > +}
> > +
> >  static int __write_tracing_file(const char *name, const char *val, bool append)
> >  {
> >         char *file;
> > @@ -586,18 +602,6 @@ static int __cmd_ftrace(struct perf_ftrace *ftrace)
> >                 .events = POLLIN,
> >         };
> >
> > -       if (!(perf_cap__capable(CAP_PERFMON) ||
> > -             perf_cap__capable(CAP_SYS_ADMIN))) {
> > -               pr_err("ftrace only works for %s!\n",
> > -#ifdef HAVE_LIBCAP_SUPPORT
> > -               "users with the CAP_PERFMON or CAP_SYS_ADMIN capability"
> > -#else
> > -               "root"
> > -#endif
> > -               );
> > -               return -1;
> > -       }
> > -
> >         select_tracer(ftrace);
> >
> >         if (reset_tracing_files(ftrace) < 0) {
> > @@ -902,18 +906,6 @@ static int __cmd_latency(struct perf_ftrace *ftrace)
> >         };
> >         int buckets[NUM_BUCKET] = { };
> >
> > -       if (!(perf_cap__capable(CAP_PERFMON) ||
> > -             perf_cap__capable(CAP_SYS_ADMIN))) {
> > -               pr_err("ftrace only works for %s!\n",
> > -#ifdef HAVE_LIBCAP_SUPPORT
> > -               "users with the CAP_PERFMON or CAP_SYS_ADMIN capability"
> > -#else
> > -               "root"
> > -#endif
> > -               );
> > -               return -1;
> > -       }
> > -
> >         trace_fd = prepare_func_latency(ftrace);
> >         if (trace_fd < 0)
> >                 goto out;
> > @@ -1220,6 +1212,10 @@ int cmd_ftrace(int argc, const char **argv)
> >         signal(SIGCHLD, sig_handler);
> >         signal(SIGPIPE, sig_handler);
> >
> > +       ret = check_ftrace_capable();
> > +       if (ret < 0)
> > +               return -1;
> > +
> >         ret = perf_config(perf_ftrace_config, &ftrace);
> >         if (ret < 0)
> >                 return -1;
> > --
> > 2.46.0.rc1.232.g9752f9e123-goog
> >

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