* Re: [PATCH] perf trace: Segfault when trying to trace events by cgroup
2020-10-19 7:43 ` [PATCH] perf trace: Segfault when trying to trace events by cgroup Stanislav Ivanichkin
@ 2020-10-23 2:48 ` Namhyung Kim
0 siblings, 0 replies; 2+ messages in thread
From: Namhyung Kim @ 2020-10-23 2:48 UTC (permalink / raw)
To: Stanislav Ivanichkin; +Cc: linux-kernel, Dmitry Monakhov, linux-perf-users
Hello,
On Tue, Oct 20, 2020 at 5:48 AM Stanislav Ivanichkin
<sivanichkin@yandex-team.ru> wrote:
>
> Hi,
>
> +linux-perf-users@
>
> Gentle ping for this patch
>
> Many Thanks
>
> --
> Stanislav Ivanichkin
>
> > On 9 Oct 2020, at 09:45, Stanislav Ivanichkin <sivanichkin@yandex-team.ru> wrote:
> >
> > # ./perf trace -e sched:sched_switch -G test -a sleep 1
> > perf: Segmentation fault
> > Obtained 11 stack frames.
> > ./perf(sighandler_dump_stack+0x43) [0x55cfdc636db3]
> > /lib/x86_64-linux-gnu/libc.so.6(+0x3efcf) [0x7fd23eecafcf]
> > ./perf(parse_cgroups+0x36) [0x55cfdc673f36]
> > ./perf(+0x3186ed) [0x55cfdc70d6ed]
> > ./perf(parse_options_subcommand+0x629) [0x55cfdc70e999]
> > ./perf(cmd_trace+0x9c2) [0x55cfdc5ad6d2]
> > ./perf(+0x1e8ae0) [0x55cfdc5ddae0]
> > ./perf(+0x1e8ded) [0x55cfdc5ddded]
> > ./perf(main+0x370) [0x55cfdc556f00]
> > /lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xe6) [0x7fd23eeadb96]
> > ./perf(_start+0x29) [0x55cfdc557389]
> > Segmentation fault
> >
> > It happens because "struct trace" in option->value is passed to
> > parse_cgroups function instead of "struct evlist".
> >
> > Signed-off-by: Stanislav Ivanichkin <sivanichkin@yandex-team.ru>
> > Reviewed-by: Dmitry Monakhov <dmtrmonakhov@yandex-team.ru>
It seems we should add this too:
Fixes: 9ea42ba4411ac ("perf trace: Support setting cgroups as targets")
> > ---
> > tools/perf/builtin-trace.c | 9 ++++++---
> > 1 file changed, 6 insertions(+), 3 deletions(-)
> >
> > diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
> > index bea461b6f937..cbc4de6840db 100644
> > --- a/tools/perf/builtin-trace.c
> > +++ b/tools/perf/builtin-trace.c
> > @@ -4651,9 +4651,12 @@ static int trace__parse_cgroups(const struct option *opt, const char *str, int u
> > {
> > struct trace *trace = opt->value;
> >
> > - if (!list_empty(&trace->evlist->core.entries))
> > - return parse_cgroups(opt, str, unset);
> > -
> > + if (!list_empty(&trace->evlist->core.entries)) {
> > + struct option o = OPT_CALLBACK('G', "cgroup", &trace->evlist,
> > + "name", "monitor event in cgroup name only",
> > + parse_cgroups);
Just make it simple and clear what parse_cgroups() expects:
struct option o = {
.value = &trace->evlist,
};
Or else, we can change parse_cgroups() to take evlist directly.
But it needs to change other callsites too.
Either is fine to me.
Thanks
Namhyung
> > + return parse_cgroups(&o, str, unset);
> > + }
> > trace->cgroup = evlist__findnew_cgroup(trace->evlist, str);
> >
> > return 0;
> > --
> > 2.17.1
> >
>
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