* [PATCH v2] perf ftrace: Detect whether ftrace is enabled on system
@ 2024-09-11 10:01 Changbin Du
2024-09-11 10:15 ` James Clark
0 siblings, 1 reply; 4+ messages in thread
From: Changbin Du @ 2024-09-11 10:01 UTC (permalink / raw)
To: Peter Zijlstra, Ingo Molnar, Arnaldo Carvalho de Melo,
Namhyung Kim
Cc: Mark Rutland, Alexander Shishkin, Jiri Olsa, Ian Rogers,
Adrian Hunter, Liang, Kan, linux-perf-users, linux-kernel,
Changbin Du
To make error messages more accurate, this change detects whether ftrace is
enabled on system by checking trace file "set_ftrace_pid".
Before:
~ # perf ftrace
failed to reset ftrace
After:
~ # perf ftrace
ftrace is not supported on this system
Signed-off-by: Changbin Du <changbin.du@huawei.com>
v2: rebase on perf-tools-next.
---
tools/perf/builtin-ftrace.c | 23 +++++++++++++++++++++++
1 file changed, 23 insertions(+)
diff --git a/tools/perf/builtin-ftrace.c b/tools/perf/builtin-ftrace.c
index 88a87bf387d2..abcdc49b7a98 100644
--- a/tools/perf/builtin-ftrace.c
+++ b/tools/perf/builtin-ftrace.c
@@ -80,6 +80,24 @@ static bool check_ftrace_capable(void)
return false;
}
+static bool is_ftrace_supported(void)
+{
+ char *file;
+ bool supported = false;
+
+ file = get_tracing_file("set_ftrace_pid");
+ if (!file) {
+ pr_debug("cannot get tracing file set_ftrace_pid\n");
+ return false;
+ }
+
+ if (!access(file, F_OK))
+ supported = true;
+
+ put_tracing_file(file);
+ return supported;
+}
+
static int __write_tracing_file(const char *name, const char *val, bool append)
{
char *file;
@@ -1583,6 +1601,11 @@ int cmd_ftrace(int argc, const char **argv)
if (!check_ftrace_capable())
return -1;
+ if (!is_ftrace_supported()) {
+ pr_err("ftrace is not supported on this system\n");
+ return -ENOTSUP;
+ }
+
ret = perf_config(perf_ftrace_config, &ftrace);
if (ret < 0)
return -1;
--
2.34.1
^ permalink raw reply related [flat|nested] 4+ messages in thread* Re: [PATCH v2] perf ftrace: Detect whether ftrace is enabled on system
2024-09-11 10:01 [PATCH v2] perf ftrace: Detect whether ftrace is enabled on system Changbin Du
@ 2024-09-11 10:15 ` James Clark
2024-09-11 12:31 ` Arnaldo Carvalho de Melo
0 siblings, 1 reply; 4+ messages in thread
From: James Clark @ 2024-09-11 10:15 UTC (permalink / raw)
To: Changbin Du
Cc: Mark Rutland, Alexander Shishkin, Jiri Olsa, Ian Rogers,
Adrian Hunter, Liang, Kan, linux-perf-users, linux-kernel,
Peter Zijlstra, Ingo Molnar, Arnaldo Carvalho de Melo,
Namhyung Kim
On 11/09/2024 11:01, Changbin Du wrote:
> To make error messages more accurate, this change detects whether ftrace is
> enabled on system by checking trace file "set_ftrace_pid".
>
> Before:
> ~ # perf ftrace
> failed to reset ftrace
>
> After:
> ~ # perf ftrace
> ftrace is not supported on this system
>
> Signed-off-by: Changbin Du <changbin.du@huawei.com>
>
> v2: rebase on perf-tools-next.
> ---
> tools/perf/builtin-ftrace.c | 23 +++++++++++++++++++++++
> 1 file changed, 23 insertions(+)
>
> diff --git a/tools/perf/builtin-ftrace.c b/tools/perf/builtin-ftrace.c
> index 88a87bf387d2..abcdc49b7a98 100644
> --- a/tools/perf/builtin-ftrace.c
> +++ b/tools/perf/builtin-ftrace.c
> @@ -80,6 +80,24 @@ static bool check_ftrace_capable(void)
> return false;
> }
>
> +static bool is_ftrace_supported(void)
> +{
> + char *file;
> + bool supported = false;
> +
> + file = get_tracing_file("set_ftrace_pid");
> + if (!file) {
> + pr_debug("cannot get tracing file set_ftrace_pid\n");
> + return false;
> + }
> +
> + if (!access(file, F_OK))
> + supported = true;
> +
> + put_tracing_file(file);
> + return supported;
> +}
> +
> static int __write_tracing_file(const char *name, const char *val, bool append)
> {
> char *file;
> @@ -1583,6 +1601,11 @@ int cmd_ftrace(int argc, const char **argv)
> if (!check_ftrace_capable())
> return -1;
>
> + if (!is_ftrace_supported()) {
> + pr_err("ftrace is not supported on this system\n");
> + return -ENOTSUP;
> + }
> +
> ret = perf_config(perf_ftrace_config, &ftrace);
> if (ret < 0)
> return -1;
Reviewed-by: James Clark <james.clark@linaro.org>
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH v2] perf ftrace: Detect whether ftrace is enabled on system
2024-09-11 10:15 ` James Clark
@ 2024-09-11 12:31 ` Arnaldo Carvalho de Melo
2024-09-12 9:54 ` duchangbin
0 siblings, 1 reply; 4+ messages in thread
From: Arnaldo Carvalho de Melo @ 2024-09-11 12:31 UTC (permalink / raw)
To: James Clark
Cc: Changbin Du, Mark Rutland, Alexander Shishkin, Jiri Olsa,
Ian Rogers, Adrian Hunter, Liang, Kan, linux-perf-users,
linux-kernel, Peter Zijlstra, Ingo Molnar, Namhyung Kim
On Wed, Sep 11, 2024 at 11:15:19AM +0100, James Clark wrote:
> On 11/09/2024 11:01, Changbin Du wrote:
> > To make error messages more accurate, this change detects whether ftrace is
> > enabled on system by checking trace file "set_ftrace_pid".
<SNIP>
> > @@ -1583,6 +1601,11 @@ int cmd_ftrace(int argc, const char **argv)
> > if (!check_ftrace_capable())
> > return -1;
> > + if (!is_ftrace_supported()) {
> > + pr_err("ftrace is not supported on this system\n");
> > + return -ENOTSUP;
> > + }
> > +
> > ret = perf_config(perf_ftrace_config, &ftrace);
> > if (ret < 0)
> > return -1;
>
> Reviewed-by: James Clark <james.clark@linaro.org>
Applied and added these comments:
Committer testing:
Doing it in an unprivileged toolbox container on Fedora 40:
Before:
acme@number:~/git/perf-tools-next$ toolbox enter perf
⬢[acme@toolbox perf-tools-next]$ sudo su -
⬢[root@toolbox ~]# ~acme/bin/perf ftrace
failed to reset ftrace
⬢[root@toolbox ~]#
After this patch:
⬢[root@toolbox ~]# ~acme/bin/perf ftrace
ftrace is not supported on this system
⬢[root@toolbox ~]#
Maybe we could check if we are in such as situation, inside an
unprivileged container, and provide a HINT line?
Reviewed-by: James Clark <james.clark@linaro.org>
Signed-off-by: Changbin Du <changbin.du@huawei.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH v2] perf ftrace: Detect whether ftrace is enabled on system
2024-09-11 12:31 ` Arnaldo Carvalho de Melo
@ 2024-09-12 9:54 ` duchangbin
0 siblings, 0 replies; 4+ messages in thread
From: duchangbin @ 2024-09-12 9:54 UTC (permalink / raw)
To: Arnaldo Carvalho de Melo
Cc: James Clark, duchangbin, Mark Rutland, Alexander Shishkin,
Jiri Olsa, Ian Rogers, Adrian Hunter, Liang, Kan,
linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org,
Peter Zijlstra, Ingo Molnar, Namhyung Kim
On Wed, Sep 11, 2024 at 09:31:02AM -0300, Arnaldo Carvalho de Melo wrote:
> On Wed, Sep 11, 2024 at 11:15:19AM +0100, James Clark wrote:
> > On 11/09/2024 11:01, Changbin Du wrote:
> > > To make error messages more accurate, this change detects whether ftrace is
> > > enabled on system by checking trace file "set_ftrace_pid".
>
> <SNIP>
>
> > > @@ -1583,6 +1601,11 @@ int cmd_ftrace(int argc, const char **argv)
> > > if (!check_ftrace_capable())
> > > return -1;
> > > + if (!is_ftrace_supported()) {
> > > + pr_err("ftrace is not supported on this system\n");
> > > + return -ENOTSUP;
> > > + }
> > > +
> > > ret = perf_config(perf_ftrace_config, &ftrace);
> > > if (ret < 0)
> > > return -1;
> >
> > Reviewed-by: James Clark <james.clark@linaro.org>
>
> Applied and added these comments:
>
> Committer testing:
>
> Doing it in an unprivileged toolbox container on Fedora 40:
>
> Before:
>
> acme@number:~/git/perf-tools-next$ toolbox enter perf
> ⬢[acme@toolbox perf-tools-next]$ sudo su -
> ⬢[root@toolbox ~]# ~acme/bin/perf ftrace
> failed to reset ftrace
> ⬢[root@toolbox ~]#
>
> After this patch:
>
> ⬢[root@toolbox ~]# ~acme/bin/perf ftrace
> ftrace is not supported on this system
> ⬢[root@toolbox ~]#
>
> Maybe we could check if we are in such as situation, inside an
> unprivileged container, and provide a HINT line?
>
I think we could check the mount status of tracefs first, and then check whether
the ftrace node exists. If there's a permission issue in container, maybe we
should also check the errno of access().
> Reviewed-by: James Clark <james.clark@linaro.org>
> Signed-off-by: Changbin Du <changbin.du@huawei.com>
> Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
--
Cheers,
Changbin Du
^ permalink raw reply [flat|nested] 4+ messages in thread
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2024-09-11 10:01 [PATCH v2] perf ftrace: Detect whether ftrace is enabled on system Changbin Du
2024-09-11 10:15 ` James Clark
2024-09-11 12:31 ` Arnaldo Carvalho de Melo
2024-09-12 9:54 ` duchangbin
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