The is_idle_sample() function actually does more than determining
whether sample come from idle task. Split the callchain part into
save_task_callchain() to make it clearer.
Also checking prev_pid from trace data looks preferred than just
checking sample->pid since it's possible, although rare, to have invalid
0 pid/tid on scheduling an exiting task.
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Acked-by: David Ahern <dsahern@gmail.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20161208144755.16673-2-namhyung@kernel.org
[ Remove some needless () in some return statements ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
make already provides the current working directory in a variable, so make
use of it instead of forking a shell. Also replace usage of PWD by
CURDIR. PWD is provided by most shells, but not all, so this makes the
build system more robust.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Michal Marek <mmarek@suse.com>
Arnaldo reported an unhelpful error message when running perf sched
timehist on a file that did not contain sched tracepoints:
[root@jouet ~]# perf sched timehist
No trace sample to read. Did you call 'perf record -R'?
[root@jouet ~]# perf evlist -v
cycles:ppp: size: 112, { sample_period, sample_freq }: 4000, sample_type: IP|TID|TIME|CALLCHAIN|CPU|PERIOD, disabled: 1, inherit: 1, mmap: 1, comm: 1, freq: 1, task: 1, precise_ip: 3, sample_id_all: 1, exclude_guest: 1, mmap2: 1, comm_exec: 1
Change the has_traces check to look for the sched_switch event. Analysis
for perf sched timehist requires at least this event.
Now when analyzing a file without sched tracepoints you get:
root@f21-vbox:/tmp$ perf sched timehist
No sched_switch events found. Have you run 'perf sched record'?
Signed-off-by: David Ahern <dsahern@gmail.com>
Reported-and-Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1480451988-43673-1-git-send-email-dsahern@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
The fixdep tool needs to be built before everything else, because it fixes
every object dependency file.
We handle this currently by making all objects to depend on fixdep, which is
error prone and is easily forgotten when new object is added.
Instead of this, this patch force fixdep tool to be built as the first target
in the separate make session. This way we don't need to handle extra fixdep
dependencies and we are certain there's no fixdep race with any parallel make
job.
Committer notes:
Testing it:
Before:
$ rm -rf /tmp/build/perf/ ; mkdir -p /tmp/build/perf ; make -k O=/tmp/build/perf -C tools/perf install-bin
make: Entering directory '/home/acme/git/linux/tools/perf'
BUILD: Doing 'make -j4' parallel build
Auto-detecting system features:
... dwarf: [ on ]
... dwarf_getlocations: [ on ]
... glibc: [ on ]
... gtk2: [ on ]
... libaudit: [ on ]
... libbfd: [ on ]
... libelf: [ on ]
... libnuma: [ on ]
... numa_num_possible_cpus: [ on ]
... libperl: [ on ]
... libpython: [ on ]
... libslang: [ on ]
... libcrypto: [ on ]
... libunwind: [ on ]
... libdw-dwarf-unwind: [ on ]
... zlib: [ on ]
... lzma: [ on ]
... get_cpuid: [ on ]
... bpf: [ on ]
GEN /tmp/build/perf/common-cmds.h
HOSTCC /tmp/build/perf/fixdep.o
HOSTLD /tmp/build/perf/fixdep-in.o
LINK /tmp/build/perf/fixdep
MKDIR /tmp/build/perf/pmu-events/
HOSTCC /tmp/build/perf/pmu-events/json.o
MKDIR /tmp/build/perf/pmu-events/
HOSTCC /tmp/build/perf/pmu-events/jsmn.o
HOSTCC /tmp/build/perf/pmu-events/jevents.o
HOSTLD /tmp/build/perf/pmu-events/jevents-in.o
PERF_VERSION = 4.9.rc8.g868cd5
CC /tmp/build/perf/perf-read-vdso32
<SNIP>
After:
$ rm -rf /tmp/build/perf/ ; mkdir -p /tmp/build/perf ; make -k O=/tmp/build/perf -C tools/perf install-bin
make: Entering directory '/home/acme/git/linux/tools/perf'
BUILD: Doing 'make -j4' parallel build
HOSTCC /tmp/build/perf/fixdep.o
HOSTLD /tmp/build/perf/fixdep-in.o
LINK /tmp/build/perf/fixdep
Auto-detecting system features:
... dwarf: [ on ]
... dwarf_getlocations: [ on ]
... glibc: [ on ]
... gtk2: [ on ]
... libaudit: [ on ]
... libbfd: [ on ]
... libelf: [ on ]
... libnuma: [ on ]
... numa_num_possible_cpus: [ on ]
... libperl: [ on ]
... libpython: [ on ]
... libslang: [ on ]
... libcrypto: [ on ]
... libunwind: [ on ]
... libdw-dwarf-unwind: [ on ]
... zlib: [ on ]
... lzma: [ on ]
... get_cpuid: [ on ]
... bpf: [ on ]
GEN /tmp/build/perf/common-cmds.h
MKDIR /tmp/build/perf/fd/
CC /tmp/build/perf/fd/array.o
LD /tmp/build/perf/fd/libapi-in.o
MKDIR /tmp/build/perf/fs/
CC /tmp/build/perf/event-parse.o
CC /tmp/build/perf/fs/fs.o
PERF_VERSION = 4.9.rc8.g57a92f
CC /tmp/build/perf/event-plugin.o
MKDIR /tmp/build/perf/fs/
CC /tmp/build/perf/fs/tracing_path.o
<SNIP>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1481030331-31944-3-git-send-email-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cancel builtin llvm and clang support when LLVM version is less than
3.9.0: following commits uses newer API.
Since Clang/LLVM's API is not guaranteed to be stable, add a
test-llvm-version.cpp feature checker, issue warning if LLVM found in
compiling environment is not tested yet.
Committer Notes:
Testing it:
Environment:
$ cat /etc/fedora-release
Fedora release 25 (Twenty Five)
$ rpm -q llvm-devel clang-devel
llvm-devel-3.8.0-1.fc25.x86_64
clang-devel-3.8.0-2.fc25.x86_64
$
Before:
$ make -k LIBCLANGLLVM=1 O=/tmp/build/perf -C tools/perf install-bin
make: Entering directory '/home/acme/git/linux/tools/perf'
BUILD: Doing 'make -j4' parallel build
Warning: tools/include/uapi/linux/bpf.h differs from kernel
Warning: tools/arch/arm/include/uapi/asm/kvm.h differs from kernel
INSTALL GTK UI
LINK /tmp/build/perf/perf
/tmp/build/perf/libperf.a(libperf-in.o): In function `perf::createCompilerInvocation(llvm::SmallVector<char const*, 16u>, llvm::StringRef&, clang::DiagnosticsEngine&)':
/home/acme/git/linux/tools/perf/util/c++/clang.cpp:56: undefined reference to `clang::tooling::newInvocation(clang::DiagnosticsEngine*, llvm::SmallVector<char const*, 16u> const&)'
/tmp/build/perf/libperf.a(libperf-in.o): In function `perf::getModuleFromSource(llvm::SmallVector<char const*, 16u>, llvm::StringRef, llvm::IntrusiveRefCntPtr<clang::vfs::FileSystem>)':
/home/acme/git/linux/tools/perf/util/c++/clang.cpp:68: undefined reference to `clang::CompilerInstance::CompilerInstance(std::shared_ptr<clang::PCHContainerOperations>, bool)'
/home/acme/git/linux/tools/perf/util/c++/clang.cpp:69: undefined reference to `clang::CompilerInstance::createDiagnostics(clang::DiagnosticConsumer*, bool)'
<SNIP>
After:
Makefile.config:807: No suitable libLLVM found, disabling builtin clang and llvm support. Please install llvm-dev(el) (>= 3.9.0)
Updating the environment to a locally built LLVM 4.0 + clang 3.9 (forgot
to git pull, duh) combo, all works as expected, it is properly detected
and built into the resulting perf binary.
Signed-off-by: Wang Nan <wangnan0@huawei.com>
Reported-and-Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexei Starovoitov <ast@fb.com>
Cc: He Kuang <hekuang@huawei.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Joe Stringer <joe@ovn.org>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
Link: http://lkml.kernel.org/r/20161206072230.7651-1-wangnan0@huawei.com
[ Change the warning message a bit (add 'suitable' and 'builtin'), clarifying it, see committer notes above ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
After this patch, perf utilizes builtin clang support to build BPF
script, no longer depend on external clang, but fallbacking to it
if for some reason the builtin compiling framework fails.
Test:
$ type clang
-bash: type: clang: not found
$ cat ~/.perfconfig
$ echo '#define LINUX_VERSION_CODE 0x040700' > ./test.c
$ cat ./tools/perf/tests/bpf-script-example.c >> ./test.c
$ ./perf record -v --dry-run -e ./test.c 2>&1 | grep builtin
bpf: successfull builtin compilation
$
Can't pass cflags so unable to include kernel headers now. Will be fixed
by following commits.
Committer notes:
Make sure '-v' comes before the '-e ./test.c' in the command line otherwise the
'verbose' variable will not be set when the bpf event is parsed and thus the
pr_debug indicating a 'successfull builtin compilation' will not be output, as
the debug level (1) will be less than what 'verbose' has at that point (0).
Signed-off-by: Wang Nan <wangnan0@huawei.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexei Starovoitov <ast@fb.com>
Cc: He Kuang <hekuang@huawei.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Joe Stringer <joe@ovn.org>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
Link: http://lkml.kernel.org/r/20161126070354.141764-16-wangnan0@huawei.com
[ Spell check/reflow successfull pr_debug string ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
getBPFObjectFromModule() is introduced to compile LLVM IR(Module)
to BPF object. Add new testcase for it.
Test result:
$ ./buildperf/perf test -v clang
51: builtin clang support :
51.1: builtin clang compile C source to IR :
--- start ---
test child forked, pid 21822
test child finished with 0
---- end ----
builtin clang support subtest 0: Ok
51.2: builtin clang compile C source to ELF object :
--- start ---
test child forked, pid 21823
test child finished with 0
---- end ----
builtin clang support subtest 1: Ok
Signed-off-by: Wang Nan <wangnan0@huawei.com>
Cc: Alexei Starovoitov <ast@fb.com>
Cc: He Kuang <hekuang@huawei.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Joe Stringer <joe@ovn.org>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
Link: http://lkml.kernel.org/r/20161126070354.141764-15-wangnan0@huawei.com
[ Remove redundant "Test" from entry descriptions ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Add basic clang support in clang.cpp and test__clang() testcase. The
first testcase checks if builtin clang is able to generate LLVM IR.
tests/clang.c is a proxy. Real testcase resides in
utils/c++/clang-test.cpp in c++ and exports C interface to perf test
subsystem.
Test result:
$ perf test -v clang
51: builtin clang support :
51.1: Test builtin clang compile C source to IR :
--- start ---
test child forked, pid 13215
test child finished with 0
---- end ----
Test builtin clang support subtest 0: Ok
Committer note:
Make sure you've enabled CLANG and LLVM builtin support by setting
the LIBCLANGLLVM variable on the make command line, e.g.:
make LIBCLANGLLVM=1 O=/tmp/build/perf -C tools/perf install-bin
Otherwise you'll get this when trying to do the 'perf test' call above:
# perf test clang
51: builtin clang support : Skip (not compiled in)
#
Signed-off-by: Wang Nan <wangnan0@huawei.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexei Starovoitov <ast@fb.com>
Cc: He Kuang <hekuang@huawei.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Joe Stringer <joe@ovn.org>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
Link: http://lkml.kernel.org/r/20161126070354.141764-11-wangnan0@huawei.com
[ Removed "Test" from descriptions, redundant and already removed from all the other entries ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Code move only; no functional change intended.
Committer notes:
Fix the build on Ubuntu 16.04 x86-64 cross-compiling to S/390, with this
set of auto-detected features:
... dwarf: [ on ]
... dwarf_getlocations: [ on ]
... glibc: [ on ]
... gtk2: [ OFF ]
... libaudit: [ OFF ]
... libbfd: [ OFF ]
... libelf: [ on ]
... libnuma: [ OFF ]
... numa_num_possible_cpus: [ OFF ]
... libperl: [ OFF ]
... libpython: [ OFF ]
... libslang: [ OFF ]
... libcrypto: [ OFF ]
... libunwind: [ OFF ]
... libdw-dwarf-unwind: [ on ]
... zlib: [ on ]
... lzma: [ OFF ]
... get_cpuid: [ OFF ]
... bpf: [ on ]
Where it was failing with:
CC /tmp/build/perf/util/time-utils.o
util/time-utils.c: In function 'parse_nsec_time':
util/time-utils.c:17:13: error: implicit declaration of function 'strtoul' [-Werror=implicit-function-declaration]
time_sec = strtoul(str, &end, 10);
^
util/time-utils.c:17:2: error: nested extern declaration of 'strtoul' [-Werror=nested-externs]
time_sec = strtoul(str, &end, 10);
^
util/time-utils.c: In function 'perf_time__parse_str':
util/time-utils.c:93:2: error: implicit declaration of function 'free' [-Werror=implicit-function-declaration]
free(str);
^
util/time-utils.c:93:2: error: incompatible implicit declaration of built-in function 'free' [-Werror]
util/time-utils.c:93:2: note: include '<stdlib.h>' or provide a declaration of 'free'
Do as suggested and add a '#include <stdlib.h>' to get the free() and strtoul()
declarations and fix the build.
Signed-off-by: David Ahern <dsahern@gmail.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1480439746-42695-3-git-send-email-dsahern@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Track freed memory as well as allocations and show the net in the
summary.
Committer notes:
Testing it:
# perf kmem record usleep 1
[ perf record: Woken up 0 times to write data ]
[ perf record: Captured and wrote 1.626 MB perf.data (4208 samples) ]
[root@jouet ~]# perf kmem stat --slab
SUMMARY (SLAB allocator)
========================
Total bytes requested: 234,011
Total bytes allocated: 234,504
Total bytes freed: 213,328 <------
Net total bytes allocated: 21,176
Total bytes wasted on internal fragmentation: 493
Internal fragmentation: 0.210231%
Cross CPU allocations: 4/1,963
#
Signed-off-by: David Ahern <dsahern@gmail.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1480110133-37039-1-git-send-email-dsahern@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Having "test" in almost all test descriptions is redundant, simplify it
removing and rewriting tests with such descriptions.
End result:
# perf test
1: vmlinux symtab matches kallsyms : Ok
2: Detect openat syscall event : Ok
3: Detect openat syscall event on all cpus : Ok
4: Read samples using the mmap interface : Ok
5: Parse event definition strings : Ok
6: PERF_RECORD_* events & perf_sample fields : Ok
7: Parse perf pmu format : Ok
8: DSO data read : Ok
9: DSO data cache : Ok
10: DSO data reopen : Ok
11: Roundtrip evsel->name : Ok
12: Parse sched tracepoints fields : Ok
13: syscalls:sys_enter_openat event fields : Ok
14: Setup struct perf_event_attr : Ok
15: Match and link multiple hists : Ok
16: 'import perf' in python : Ok
17: Breakpoint overflow signal handler : Ok
18: Breakpoint overflow sampling : Ok
19: Number of exit events of a simple workload : Ok
20: Software clock events period values : Ok
21: Object code reading : Ok
22: Sample parsing : Ok
23: Use a dummy software event to keep tracking: Ok
24: Parse with no sample_id_all bit set : Ok
25: Filter hist entries : Ok
26: Lookup mmap thread : Ok
27: Share thread mg : Ok
28: Sort output of hist entries : Ok
29: Cumulate child hist entries : Ok
30: Track with sched_switch : Ok
31: Filter fds with revents mask in a fdarray : Ok
32: Add fd to a fdarray, making it autogrow : Ok
33: kmod_path__parse : Ok
34: Thread map : Ok
35: LLVM search and compile :
35.1: Basic BPF llvm compile : Ok
35.2: kbuild searching : Ok
35.3: Compile source for BPF prologue generation: Ok
35.4: Compile source for BPF relocation : Ok
36: Session topology : Ok
37: BPF filter :
37.1: Basic BPF filtering : Ok
37.2: BPF prologue generation : Ok
37.3: BPF relocation checker : Ok
38: Synthesize thread map : Ok
39: Synthesize cpu map : Ok
40: Synthesize stat config : Ok
41: Synthesize stat : Ok
42: Synthesize stat round : Ok
43: Synthesize attr update : Ok
44: Event times : Ok
45: Read backward ring buffer : Ok
46: Print cpu map : Ok
47: Probe SDT events : Ok
48: is_printable_array : Ok
49: Print bitmap : Ok
50: perf hooks : Ok
51: x86 rdpmc : Ok
52: Convert perf time to TSC : Ok
53: DWARF unwind : Ok
54: x86 instruction decoder - new instructions : Ok
55: Intel cqm nmi context read : Skip
#
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-rx2lbfcrrio2yx1fxcljqy0e@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Perf hooks allow hooking user code at perf events. They can be used for
manipulation of BPF maps, taking snapshot and reporting results. In this
patch two perf hook points are introduced: record_start and record_end.
To avoid buggy user actions, a SIGSEGV signal handler is introduced into
'perf record'. It turns off perf hook if it causes a segfault and report
an error to help debugging.
A test case for perf hook is introduced.
Test result:
$ ./buildperf/perf test -v hook
50: Test perf hooks :
--- start ---
test child forked, pid 10311
SIGSEGV is observed as expected, try to recover.
Fatal error (SEGFAULT) in perf hook 'test'
test child finished with 0
---- end ----
Test perf hooks: Ok
Signed-off-by: Wang Nan <wangnan0@huawei.com>
Cc: Alexei Starovoitov <ast@fb.com>
Cc: He Kuang <hekuang@huawei.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Joe Stringer <joe@ovn.org>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
Link: http://lkml.kernel.org/r/20161126070354.141764-5-wangnan0@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Before this patch perf panics if kptr_restrict is set to 1 and perf is
owned by root with suid set:
$ whoami
wangnan
$ ls -l ./perf
-rwsr-xr-x 1 root root 19781908 Sep 21 19:29 /home/wangnan/perf
$ cat /proc/sys/kernel/kptr_restrict
1
$ cat /proc/sys/kernel/perf_event_paranoid
-1
$ ./perf record -a
Segmentation fault (core dumped)
$
The reason is that perf assumes it is allowed to read kptr from
/proc/kallsyms when euid is root, but in fact the kernel doesn't allow
reading kptr when euid and uid do not match with each other:
$ cp /bin/cat .
$ sudo chown root:root ./cat
$ sudo chmod u+s ./cat
$ cat /proc/kallsyms | grep do_fork
0000000000000000 T _do_fork <--- kptr is hidden even euid is root
$ sudo cat /proc/kallsyms | grep do_fork
ffffffff81080230 T _do_fork
See lib/vsprintf.c for kernel side code.
This patch fixes this problem by checking both uid and euid.
Signed-off-by: Wang Nan <wangnan0@huawei.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexei Starovoitov <ast@fb.com>
Cc: He Kuang <hekuang@huawei.com>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
Link: http://lkml.kernel.org/r/20161115040617.69788-3-wangnan0@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
On ubuntu the internal kernel version code is different from what can
be retrived from uname:
$ uname -r
4.4.0-47-generic
$ cat /lib/modules/`uname -r`/build/include/generated/uapi/linux/version.h
#define LINUX_VERSION_CODE 263192
#define KERNEL_VERSION(a,b,c) (((a) << 16) + ((b) << 8) + (c))
$ cat /lib/modules/`uname -r`/build/include/generated/utsrelease.h
#define UTS_RELEASE "4.4.0-47-generic"
#define UTS_UBUNTU_RELEASE_ABI 47
$ cat /proc/version_signature
Ubuntu 4.4.0-47.68-generic 4.4.24
The macro LINUX_VERSION_CODE is set to 4.4.24 (263192 == 0x40418), but
`uname -r` reports 4.4.0.
This mismatch causes LINUX_VERSION_CODE macro passed to BPF script become
an incorrect value, results in magic failure in BPF loading:
$ sudo ./buildperf/perf record -e ./tools/perf/tests/bpf-script-example.c ls
event syntax error: './tools/perf/tests/bpf-script-example.c'
\___ Failed to load program for unknown reason
According to Ubuntu document (https://wiki.ubuntu.com/Kernel/FAQ), the
correct kernel version can be retrived through /proc/version_signature, which
is ubuntu specific.
This patch checks the existance of /proc/version_signature, and returns
version number through parsing this file instead of uname. Version string
is untouched (value returns from uname) because `uname -r` is required
to be consistence with path of kbuild directory in /lib/module.
Signed-off-by: Wang Nan <wangnan0@huawei.com>
Cc: Alexei Starovoitov <ast@fb.com>
Cc: He Kuang <hekuang@huawei.com>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
Link: http://lkml.kernel.org/r/20161115040617.69788-2-wangnan0@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
