Re: [PATCH 5/7] perf session: don't rely on evlist in pipe mode

David Carrillo-Cisneros
2017-04-11T18:59:22Z

Only the second one is needed. file is already checked for the first one.

On Tue, Apr 11, 2017 at 11:44 AM, Arnaldo Carvalho de Melo
<acme@kernel.org> wrote:
> Em Tue, Apr 11, 2017 at 03:40:50PM -0300, Arnaldo Carvalho de Melo escreveu:
>> Em Tue, Apr 11, 2017 at 03:40:14PM -0300, Arnaldo Carvalho de Melo escreveu:
>> > Em Mon, Apr 10, 2017 at 01:14:30PM -0700, David Carrillo-Cisneros escreveu:
>> > > Session sets a number parameters that rely on evlist. These parameters
>> > > are not used in pipe-mode and should not be set, since evlist is
>> > > unavailable. Fix that.
>> >
>> > Ditching this one as well, until further investigation, well, file must
>> > be null in this case...
>
> This should be enough, right?
>
> diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
> index db554b7461b8..37cf4e6abf9f 100644
> --- a/tools/perf/util/session.c
> +++ b/tools/perf/util/session.c
> @@ -144,7 +144,7 @@ struct perf_session *perf_session__new(struct perf_data_file *file,
> * set session attributes that are present in perf.data
> * but not in pipe-mode.
> */
> - if (!file->is_pipe) {
> + if (!file || !file->is_pipe) {
> perf_session__set_id_hdr_size(session);
> perf_session__set_comm_exec(session);
> }
> @@ -166,7 +166,7 @@ struct perf_session *perf_session__new(struct perf_data_file *file,
> * In pipe-mode, evlist is empty until PERF_RECORD_HEADER_ATTR is
> * processed, so perf_evlist__sample_id_all is not meaningful here.
> */
> - if (!file->is_pipe && tool && tool->ordering_requires_timestamps &&
> + if ((!file || !file->is_pipe) && tool && tool->ordering_requires_timestamps &&
> tool->ordered_events && !perf_evlist__sample_id_all(session->evlist)) {
> dump_printf("WARNING: No sample_id_all support, falling back to unordered processing\n");
> tool->ordered_events = false;
>
>> Ah, this is the problem:
>>
>> [root@jouet ~]# perf top
>> perf: Segmentation fault
>> -------- backtrace --------
>> perf[0x57eddb]
>> /lib64/libc.so.6(+0x35990)[0x7fb435d06990]
>> perf(perf_session__new+0xb7)[0x4eb547]
>> perf(cmd_top+0xde9)[0x44ce89]
>> perf[0x49953f]
>> perf[0x499831]
>> perf(main+0x252)[0x428dd2]
>> /lib64/libc.so.6(__libc_start_main+0xf1)[0x7fb435cf1401]
>> perf(_start+0x2a)[0x4292da]
>> [0x0]
>> [root@jouet ~]#
>>
>> > [acme@jouet linux]$ git bisect bad
>> > 5d71c27204d51492abe9fc69064fd36a0bda410b is the first bad commit
>> > commit 5d71c27204d51492abe9fc69064fd36a0bda410b
>> > Author: David Carrillo-Cisneros <davidcc@google.com>
>> > Date: Mon Apr 10 13:14:30 2017 -0700
>> >
>> > perf session: Don't rely on evlist in pipe mode
>> >
>> > Session sets a number parameters that rely on evlist. These parameters
>> > are not used in pipe-mode and should not be set, since evlist is
>> > unavailable. Fix that.
>> >
>> > Signed-off-by: David Carrillo-Cisneros <davidcc@google.com>
>> > Acked-by: Jiri Olsa <jolsa@kernel.org>
>> > Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
>> > Cc: Andi Kleen <ak@linux.intel.com>
>> > Cc: He Kuang <hekuang@huawei.com>
>> > Cc: Masami Hiramatsu <mhiramat@kernel.org>
>> > Cc: Paul Turner <pjt@google.com>
>> > Cc: Peter Zijlstra <peterz@infradead.org>
>> > Cc: Simon Que <sque@chromium.org>
>> > Cc: Stephane Eranian <eranian@google.com>
>> > Cc: Wang Nan <wangnan0@huawei.com>
>> > Link: http://lkml.kernel.org/r/20170410201432.24807-6-davidcc@google.com
>> > Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
>> >
>> > :040000 040000 7df28fe9d7c9d962b78c0532f4961caea2737b59 34e4fed0042b1401c1a1a247d8ae40df17f9d272 M tools
>> > [acme@jouet linux]$
>> >
>> > > Signed-off-by: David Carrillo-Cisneros <davidcc@google.com>
>> > > ---
>> > > tools/perf/util/session.c | 16 +++++++++++++---
>> > > 1 file changed, 13 insertions(+), 3 deletions(-)
>> > >
>> > > diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
>> > > index a25302bc55a8..db554b7461b8 100644
>> > > --- a/tools/perf/util/session.c
>> > > +++ b/tools/perf/util/session.c
>> > > @@ -140,8 +140,14 @@ struct perf_session *perf_session__new(struct perf_data_file *file,
>> > > if (perf_session__open(session) < 0)
>> > > goto out_close;
>> > >
>> > > - perf_session__set_id_hdr_size(session);
>> > > - perf_session__set_comm_exec(session);
>> > > + /*
>> > > + * set session attributes that are present in perf.data
>> > > + * but not in pipe-mode.
>> > > + */
>> > > + if (!file->is_pipe) {
>> > > + perf_session__set_id_hdr_size(session);
>> > > + perf_session__set_comm_exec(session);
>> > > + }
>> > > }
>> > > } else {
>> > > session->machines.host.env = &perf_env;
>> > > @@ -156,7 +162,11 @@ struct perf_session *perf_session__new(struct perf_data_file *file,
>> > > pr_warning("Cannot read kernel map\n");
>> > > }
>> > >
>> > > - if (tool && tool->ordering_requires_timestamps &&
>> > > + /*
>> > > + * In pipe-mode, evlist is empty until PERF_RECORD_HEADER_ATTR is
>> > > + * processed, so perf_evlist__sample_id_all is not meaningful here.
>> > > + */
>> > > + if (!file->is_pipe && tool && tool->ordering_requires_timestamps &&
>> > > tool->ordered_events && !perf_evlist__sample_id_all(session->evlist)) {
>> > > dump_printf("WARNING: No sample_id_all support, falling back to unordered processing\n");
>> > > tool->ordered_events = false;
>> > > --
>> > > 2.12.2.715.g7642488e1d-goog