Commits · 12c1a415eb8dc258a33f04d6a4df288e0cc4e200 · Kirill Smelkov / linux

11 Feb, 2021 5 commits

perf daemon: Add signalfd support · 12c1a415

Jiri Olsa authored Feb 08, 2021

Use a signalfd fd to track SIGCHLD signals as notifications for perf
session termination.

This way we don't need to actively check for child status, being
notified if there's change.
Suggested-by: Alexei Budankov <abudankov@huawei.com>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: https://lore.kernel.org/r/20210208200908.1019149-10-jolsa@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

12c1a415

perf daemon: Add background support · 88adb119

Jiri Olsa authored Feb 08, 2021

Add support to put the daemon process in the background.

It's now enabled by default and -f option is added to keep the daemon
process on the console for debugging.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexei Budankov <abudankov@huawei.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: https://lore.kernel.org/r/20210208200908.1019149-9-jolsa@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

88adb119

perf daemon: Add config file change check · 3cda0625

Jiri Olsa authored Feb 08, 2021

Add support to detect changes to the daemon's config file triggering a
re-read of the configuration when that happens.

Use a inotify file descriptor plugged into the main fdarray object for
polling.

Example:

  # cat ~/.perfconfig
  [daemon]
  base=/opt/perfdata

  [session-cycles]
  run = -m 10M -e cycles --overwrite --switch-output -a

Starting the daemon:

  # perf daemon start

Check sessions:

  # perf daemon
  [772262:daemon] base: /opt/perfdata
  [772263:cycles] perf record -m 10M -e cycles --overwrite --switch-output -a

Change '-m 10M' to '-m 20M', and check daemon log:

  # tail -f /opt/perfdata/output
  [2021-01-02 20:31:41.234045] daemon started (pid 772262)
  [2021-01-02 20:31:41.235072] reconfig: ruining session [cycles:772263]: -m 10M -e cycles --overwrite --switch-output -a
  [2021-01-02 20:32:08.310137] reconfig: session 'cycles' killed
  [2021-01-02 20:32:08.310847] reconfig: ruining session [cycles:772338]: -m 20M -e cycles --overwrite --switch-output -a

And the session list:

  # perf daemon
  [772262:daemon] base: /opt/perfdata
  [772338:cycles] perf record -m 20M -e cycles --overwrite --switch-output -a

Note the changed '-m 20M' option is in place.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexei Budankov <abudankov@huawei.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: https://lore.kernel.org/r/20210208200908.1019149-8-jolsa@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

3cda0625

perf daemon: Add config file support · c0666261

Jiri Olsa authored Feb 08, 2021

Adding support to configure daemon with config file.

Each client or server invocation of perf daemon needs to know the
base directory, where all sessions data is stored.

The base is defined with:

  daemon.base
    Base path for daemon data. All sessions data are stored under
    this path.

The daemon allows to create record sessions. Each session is a
record command spawned and monitored by perf daemon.

The session is defined with:

  session-<NAME>.run
    Defines new record session for daemon. The value is record's
    command line without the 'record' keyword.

Example:

  # cat ~/.perfconfig
  [daemon]
  base=/opt/perfdata

  [session-cycles]
  run = -m 10M -e cycles --overwrite --switch-output -a

  [session-sched]
  run = -m 20M -e sched:* --overwrite --switch-output -a

The example above defines '/opt/perfdata' as the base directory and 2
record sessions.

  # perf daemon start
  [2021-01-28 19:47:33.454413] daemon started (pid 16015)
  [2021-01-28 19:47:33.455910] reconfig: ruining session [cycles:16016]: -m 10M -e cycles --overwrite --switch-output -a
  [2021-01-28 19:47:33.456599] reconfig: ruining session [sched:16017]: -m 20M -e sched:* --overwrite --switch-output -a

  # ps -ef | grep perf
  ... perf daemon start
  ... /home/jolsa/.../perf record -m 20M -e cycles --overwrite --switch-output -a
  ... /home/jolsa/.../perf record -m 20M -e sched:* --overwrite --switch-output -a

The base directory is populated with:

  # find /opt/perfdata/
  /opt/perfdata/
  /opt/perfdata/control                    <- control socket
  /opt/perfdata/session-cycles             <- data for session 'cycles':
  /opt/perfdata/session-cycles/output      <-   perf record output
  /opt/perfdata/session-cycles/perf.data   <-   perf data
  /opt/perfdata/session-sched              <- ditto for session 'sched'
  /opt/perfdata/session-sched/output
  /opt/perfdata/session-sched/perf.data
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexei Budankov <abudankov@huawei.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: https://lore.kernel.org/r/20210208200908.1019149-7-jolsa@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

c0666261

perf daemon: Add client socket support · 90b0aad8

Jiri Olsa authored Feb 08, 2021

Add support for client socket side that will be used to send commands to
the daemon server socket.

This patch adds only the core support, all commands using this
functionality are coming in the following patches.

Committer notes:

Hat to patch patch it to deal with this in some systems:

  cc1: warnings being treated as errors
  builtin-daemon.c: In function 'send_cmd':  MKDIR    /tmp/build/perf/bench/

  builtin-daemon.c:1368: error: ignoring return value of 'fwrite', declared with attribute warn_unused_result
    MKDIR    /tmp/build/perf/tests/
  make[3]: *** [/tmp/build/perf/builtin-daemon.o] Error 1

And also to not leak the 'line' buffer allocated by getline(), since you
initialized line to NULL and len to zero, man page says:

  If *lineptr is set to NULL and *n is set 0 before the call,
  then getline() will allocate a buffer for storing the line.
  This buffer should be freed by the user program even if
  getline() failed.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexei Budankov <abudankov@huawei.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: https://lore.kernel.org/r/20210208200908.1019149-6-jolsa@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

90b0aad8

09 Feb, 2021 7 commits

perf daemon: Add server socket support · ed36b704

Jiri Olsa authored Feb 08, 2021

Add support to create a server socket that listens for client commands
and processes them.

This patch adds only the core support, all commands using this
functionality are coming in the following patches.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexei Budankov <abudankov@huawei.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: https://lore.kernel.org/r/20210208200908.1019149-5-jolsa@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

ed36b704

perf daemon: Add base option · 5631d100

Jiri Olsa authored Feb 08, 2021

Add a base option allowing the user to specify a base directory.  It
will have precedence over config file base definition coming in the
following patches.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexei Budankov <abudankov@huawei.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: https://lore.kernel.org/r/20210208200908.1019149-4-jolsa@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

5631d100

perf daemon: Add config option · fc1dcb1e

Jiri Olsa authored Feb 08, 2021

Add a config option and base functionality that takes the option
argument (if specified) and other system config locations and produces
an 'acting' config file path.

The actual config file processing is coming in following patches.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexei Budankov <abudankov@huawei.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: https://lore.kernel.org/r/20210208200908.1019149-3-jolsa@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

fc1dcb1e

perf daemon: Add daemon command · d450bc50

Jiri Olsa authored Feb 08, 2021

Add a daemon skeleton with a minimal base (non) functionality, covering
various setup in start command.

Add an initial perf-daemon.txt with basic info.

This is in response to pople asking for the possibility to be able run
record long running sessions on the background.

The patchset that starts with this adds support to configure and run
record sessions on background via new 'perf daemon' command.

This is useful for being able to use perf as a flight recorder that one
can interact with asking for events to be enabled or disabled, added or
removed, etc.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexei Budankov <abudankov@huawei.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: https://lore.kernel.org/r/20210208200908.1019149-2-jolsa@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

d450bc50

perf script: Simplify bool conversion · 8524711d

Yang Li authored Feb 08, 2021

  Fix the following coccicheck warning:
  ./tools/perf/builtin-script.c:2789:36-41: WARNING: conversion to bool
  not needed here
  ./tools/perf/builtin-script.c:3237:48-53: WARNING: conversion to bool
  not needed here
Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Yang Li <yang.lee@linux.alibaba.com>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: KP Singh <kpsingh@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Martin KaFai Lau <kafai@fb.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Song Liu <songliubraving@fb.com>
Cc: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/r/1612773936-98691-1-git-send-email-yang.lee@linux.alibaba.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

8524711d

perf arm64/s390: Fix printf conversion specifier for IP addresses · 6db59d35

Arnaldo Carvalho de Melo authored Feb 09, 2021

We need to use "%#" PRIx64 for u64 values, not "%lx". In arm64's and
s390x cases the compiler doesn't complain, but lets fix this in case
this code gets copied to a 32-bit arch, like with powerpc 32-bit that
got fixed in the previous patch.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Hewenliang <hewenliang4@huawei.com>
Cc: Hu Shiyuan <hushiyuan@huawei.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Richter <tmricht@linux.ibm.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

6db59d35

perf powerpc: Fix printf conversion specifier for IP addresses · 0f000f9c

Arnaldo Carvalho de Melo authored Feb 09, 2021

We need to use "%#" PRIx64 for u64 values, not "%lx", fixing this build
problem on powerpc 32-bit:

  72    13.69 ubuntu:18.04-x-powerpc        : FAIL powerpc-linux-gnu-gcc (Ubuntu 7.5.0-3ubuntu1~18.04) 7.5.0
    arch/powerpc/util/machine.c: In function 'arch__symbols__fixup_end':
    arch/powerpc/util/machine.c:23:12: error: format '%lx' expects argument of type 'long unsigned int', but argument 6 has type 'u64 {aka long long unsigned int}' [-Werror=format=]
      pr_debug4("%s sym:%s end:%#lx\n", __func__, p->name, p->end);
                ^
    /git/linux/tools/perf/util/debug.h:18:21: note: in definition of macro 'pr_fmt'
     #define pr_fmt(fmt) fmt
                         ^~~
    /git/linux/tools/perf/util/debug.h:33:29: note: in expansion of macro 'pr_debugN'
     #define pr_debug4(fmt, ...) pr_debugN(4, pr_fmt(fmt), ##__VA_ARGS__)
                                 ^~~~~~~~~
    /git/linux/tools/perf/util/debug.h:33:42: note: in expansion of macro 'pr_fmt'
     #define pr_debug4(fmt, ...) pr_debugN(4, pr_fmt(fmt), ##__VA_ARGS__)
                                              ^~~~~~
    arch/powerpc/util/machine.c:23:2: note: in expansion of macro 'pr_debug4'
      pr_debug4("%s sym:%s end:%#lx\n", __func__, p->name, p->end);
      ^~~~~~~~~
    cc1: all warnings being treated as errors
    /git/linux/tools/build/Makefile.build:139: recipe for target 'util' failed
    make[5]: *** [util] Error 2
    /git/linux/tools/build/Makefile.build:139: recipe for target 'powerpc' failed
    make[4]: *** [powerpc] Error 2
    /git/linux/tools/build/Makefile.build:139: recipe for target 'arch' failed
    make[3]: *** [arch] Error 2
  73    30.47 ubuntu:18.04-x-powerpc64      : Ok   powerpc64-linux-gnu-gcc (Ubuntu 7.5.0-3ubuntu1~18.04) 7.5.0

Fixes: 557c3ead ("perf powerpc: Fix gap between kernel end and module start")
Cc: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Kajol Jain <kjain@linux.ibm.com>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

0f000f9c

08 Feb, 2021 14 commits

perf script: Support filtering by hex address · 61d9fc44

Jin Yao authored Feb 07, 2021

'perf script' supports '-S' or '--symbol' options to only list the
records for these symbols. A symbol is typically a name or hex address.
If it's hex address, it is the start address of one symbol.

While it would be useful if we can filter trace records by any hex
address (not only the start address of symbol). So now we support
filtering trace records by more conditions, such as:

- symbol name
- start address of symbol
- any hexadecimal address
- address range

The comparison order is defined as:

1. symbol name comparison
2. symbol start address comparison.
3. any hexadecimal address comparison.
4. address range comparison.

The idea is if we can get a valid address from -S list, we add the
address to addr_list for address comparison otherwise we still leave
it to sym_list for symbol comparison.

Some examples:

  root@kbl-ppc:~# ./perf script -S ffffffff9a477308
            perf  8562 [000] 347303.578858:          1   cycles:  ffffffff9a477308 native_write_msr+0x8 ([kernel.kallsyms])
            perf  8562 [000] 347303.578860:          1   cycles:  ffffffff9a477308 native_write_msr+0x8 ([kernel.kallsyms])
            perf  8562 [000] 347303.578861:         11   cycles:  ffffffff9a477308 native_write_msr+0x8 ([kernel.kallsyms])
            perf  8562 [001] 347303.578903:          1   cycles:  ffffffff9a477308 native_write_msr+0x8 ([kernel.kallsyms])
            perf  8562 [001] 347303.578905:          1   cycles:  ffffffff9a477308 native_write_msr+0x8 ([kernel.kallsyms])
            perf  8562 [001] 347303.578906:         15   cycles:  ffffffff9a477308 native_write_msr+0x8 ([kernel.kallsyms])
            perf  8562 [002] 347303.578952:          1   cycles:  ffffffff9a477308 native_write_msr+0x8 ([kernel.kallsyms])
            perf  8562 [002] 347303.578953:          1   cycles:  ffffffff9a477308 native_write_msr+0x8 ([kernel.kallsyms])

Filter the traced records by hex address ffffffff9a477308.

  root@kbl-ppc:~# ./perf script -S ffffffff9a4dd4ce,ffffffff9a4d2de9,ffffffff9a6bf9f4
            perf  8562 [001] 347303.578911:     311706   cycles:  ffffffff9a6bf9f4 __kmalloc_node+0x204 ([kernel.kallsyms])
            perf  8562 [002] 347303.578960:     354477   cycles:  ffffffff9a4d2de9 sched_setaffinity+0x49 ([kernel.kallsyms])
            perf  8562 [003] 347303.579015:     450958   cycles:  ffffffff9a4dd4ce dequeue_task_fair+0x1ae ([kernel.kallsyms])

Filter the traced records by hex address ffffffff9a4dd4ce, ffffffff9a4d2de9, ffffffff9a6bf9f4.

  root@kbl-ppc:~# ./perf script -S ffffffff9a477309 --addr-range 16
            perf  8562 [000] 347303.578863:        291   cycles:  ffffffff9a47730a native_write_msr+0xa ([kernel.kallsyms])
            perf  8562 [001] 347303.578907:        411   cycles:  ffffffff9a47730a native_write_msr+0xa ([kernel.kallsyms])
            perf  8562 [002] 347303.578956:        462   cycles:  ffffffff9a47730f native_write_msr+0xf ([kernel.kallsyms])
            perf  8562 [003] 347303.579010:        497   cycles:  ffffffff9a47730f native_write_msr+0xf ([kernel.kallsyms])
            perf  8562 [004] 347303.579059:        429   cycles:  ffffffff9a47730f native_write_msr+0xf ([kernel.kallsyms])
            perf  8562 [005] 347303.579109:        408   cycles:  ffffffff9a47730a native_write_msr+0xa ([kernel.kallsyms])
            perf  8562 [006] 347303.579159:        460   cycles:  ffffffff9a47730f native_write_msr+0xf ([kernel.kallsyms])
            perf  8562 [007] 347303.579213:        436   cycles:  ffffffff9a47730f native_write_msr+0xf ([kernel.kallsyms])

Filter the traced records from address range [ffffffff9a477309, ffffffff9a477309 + 15].

  root@kbl-ppc:~# ./perf script -S "ffffffff9b163046,rcu_nmi_exit"
            perf  8562 [004] 347303.579060:      12013   cycles:  ffffffff9b163046 exc_nmi+0x166 ([kernel.kallsyms])
            perf  8562 [007] 347303.579214:      12138   cycles:  ffffffff9b165944 rcu_nmi_exit+0x34 ([kernel.kallsyms])

Filter by address + symbol
Signed-off-by: Jin Yao <yao.jin@linux.intel.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jin Yao <yao.jin@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20210207080935.31784-2-yao.jin@linux.intel.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

61d9fc44

perf intlist: Change 'struct intlist' int member to 'unsigned long' · 94253393

Jin Yao authored Feb 07, 2021

This is to let intlist support addresses as its payload.

One potential problem is it can't support negative number. But so far,
there is no such kind of use case.
Signed-off-by: Jin Yao <yao.jin@linux.intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jin Yao <yao.jin@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20210207080935.31784-1-yao.jin@linux.intel.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

94253393

perf stat: Use nftw() instead of ftw() · a81fbb87

Paul Cercueil authored Feb 08, 2021

ftw() has been obsolete for about 12 years now.

Committer notes:

Further notes provided by the patch author:

    "NOTE: Not runtime-tested, I have no idea what I need to do in perf
     to test this. But at least it compiles now with my uClibc-based
     toolchain."

I looked at the nftw()/ftw() man page and for the use made with cgroups
in 'perf stat' the end result is equivalent.

Fixes: bb1c15b6 ("perf stat: Support regex pattern in --for-each-cgroup")
Signed-off-by: Paul Cercueil <paul@crapouillou.net>
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: od@zcrc.me
Cc: stable@vger.kernel.org
Link: http://lore.kernel.org/lkml/20210208181157.1324550-1-paul@crapouillou.netSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>