Re: [PATCH] Revert "perf cs-etm: Move definition of 'traceid_list' global variable from header file"

Andrey Zhizhikin
2020-11-20T12:16:36Z

On Fri, Nov 20, 2020 at 12:19 PM Leo Yan <leo.yan@linaro.org> wrote:
>
> On Fri, Nov 20, 2020 at 10:54:22AM +0100, Andrey Zhizhikin wrote:
> > On Fri, Nov 20, 2020 at 8:39 AM Salvatore Bonaccorso <carnil@debian.org> wrote:
> > >
> > > This reverts commit 168200b6d6ea0cb5765943ec5da5b8149701f36a upstream.
> > > (but only from 4.19.y)
> >
> > This revert would fail the build of 4.19.y with gcc10, I believe the
> > original commit was introduced to address exactly this case. If this
> > is intended behavior that 4.19.y is not compiled with newer gcc
> > versions - then this revert is OK.
>
> The original commit has a dependency for commit 95c6fe970a01 ("perf
> cs-etm: Change tuple from traceID-CPU# to traceID-metadata"). If the
> commit 95c6fe970a01 is not backported on v4.19.y, then I think reverting
> in this patch is the right way to do.

Commit 95c6fe970a01 (perf cs-etm: Change tuple from traceID-CPU# to
traceID-metadata) did not change a definition of traceid_list in
tools/perf/util/cs-etm.h header file rather a comment above it.

Definition of traceid_list in tools/perf/util/cs-etm.h header file was
done in commit cd8bfd8c973ea (perf tools: Add processing of coresight
metadata) which appears in all branches starting from linux-4.16.y.

The issue with this definition of traceid_list in header file would
break perf builds with newer gcc versions if this commit would be
reverted, so I believe that than rather reverting - commit
95c6fe970a01 ("perf
cs-etm: Change tuple from traceID-CPU# to traceID-metadata") should be
backported onto 4.19.y instead.

Or am I missing something else here?

>
> Thanks,
> Leo
>
> > > The original commit introduces a build failure as seen on Debian buster
> > > when compiled with gcc (Debian 8.3.0-6) 8.3.0:
> > >
> > > $ LC_ALL=C.UTF-8 ARCH=x86 make perf
> > > [...]
> > > Warning: Kernel ABI header at 'tools/include/uapi/linux/bpf.h' differs from latest version at 'include/uapi/linux/bpf.h'
> > > CC util/cs-etm-decoder/cs-etm-decoder.o
> > > CC util/intel-pt.o
> > > util/cs-etm-decoder/cs-etm-decoder.c: In function 'cs_etm_decoder__buffer_packet':
> > > util/cs-etm-decoder/cs-etm-decoder.c:287:24: error: 'traceid_list' undeclared (first use in this function); did you mean 'trace_event'?
> > > inode = intlist__find(traceid_list, trace_chan_id);
> > > ^~~~~~~~~~~~
> > > trace_event
> > > util/cs-etm-decoder/cs-etm-decoder.c:287:24: note: each undeclared identifier is reported only once for each function it appears in
> > > make[6]: *** [/build/linux-stable/tools/build/Makefile.build:97: util/cs-etm-decoder/cs-etm-decoder.o] Error 1
> > > make[5]: *** [/build/linux-stable/tools/build/Makefile.build:139: cs-etm-decoder] Error 2
> > > make[5]: *** Waiting for unfinished jobs....
> > > make[4]: *** [/build/linux-stable/tools/build/Makefile.build:139: util] Error 2
> > > make[3]: *** [Makefile.perf:633: libperf-in.o] Error 2
> > > make[2]: *** [Makefile.perf:206: sub-make] Error 2
> > > make[1]: *** [Makefile:70: all] Error 2
> > > make: *** [Makefile:77: perf] Error 2
> > >
> > > Link: https://lore.kernel.org/stable/20201114083501.GA468764@eldamar.lan/
> > > Cc: Leo Yan <leo.yan@linaro.org>
> > > Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
> > > Cc: Jiri Olsa <jolsa@redhat.com>
> > > Cc: Mark Rutland <mark.rutland@arm.com>
> > > Cc: Namhyung Kim <namhyung@kernel.org>
> > > Cc: Peter Zijlstra <peterz@infradead.org>
> > > Cc: Suzuki Poulouse <suzuki.poulose@arm.com>
> > > Cc: Tor Jeremiassen <tor@ti.com>
> > > Cc: linux-arm-kernel@lists.infradead.org
> > > Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
> > > Cc: Guenter Roeck <linux@roeck-us.net>
> > > Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> > > Cc: <stable@vger.kernel.org> # 4.19.y
> > > Signed-off-by: Salvatore Bonaccorso <carnil@debian.org>
> > > ---
> > > tools/perf/util/cs-etm.c | 3 ---
> > > tools/perf/util/cs-etm.h | 3 +++
> > > 2 files changed, 3 insertions(+), 3 deletions(-)
> > >
> > > diff --git a/tools/perf/util/cs-etm.c b/tools/perf/util/cs-etm.c
> > > index ad33b99f5d21..7b5e15cc6b71 100644
> > > --- a/tools/perf/util/cs-etm.c
> > > +++ b/tools/perf/util/cs-etm.c
> > > @@ -87,9 +87,6 @@ struct cs_etm_queue {
> > > struct cs_etm_packet *packet;
> > > };
> > >
> > > -/* RB tree for quick conversion between traceID and metadata pointers */
> > > -static struct intlist *traceid_list;
> > > -
> > > static int cs_etm__update_queues(struct cs_etm_auxtrace *etm);
> > > static int cs_etm__process_timeless_queues(struct cs_etm_auxtrace *etm,
> > > pid_t tid, u64 time_);
> > > diff --git a/tools/perf/util/cs-etm.h b/tools/perf/util/cs-etm.h
> > > index c7ef97b198c7..37f8d48179ca 100644
> > > --- a/tools/perf/util/cs-etm.h
> > > +++ b/tools/perf/util/cs-etm.h
> > > @@ -53,6 +53,9 @@ enum {
> > > CS_ETMV4_PRIV_MAX,
> > > };
> > >
> > > +/* RB tree for quick conversion between traceID and CPUs */
> > > +struct intlist *traceid_list;
> > > +
> > > #define KiB(x) ((x) * 1024)
> > > #define MiB(x) ((x) * 1024 * 1024)
> > >
> > > --
> > > 2.29.2
> > >
> >
> >
> > --
> > Regards,
> > Andrey.

--
Regards,
Andrey.