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    Subject[tip:perf/core] ftrace/perf: Check sample types only for sampling events
    Commit-ID:  0a74c5b3d20d2a8693848b6ae4f1a97624f5b781
    Gitweb: http://git.kernel.org/tip/0a74c5b3d20d2a8693848b6ae4f1a97624f5b781
    Author: Jiri Olsa <jolsa@kernel.org>
    AuthorDate: Wed, 16 Mar 2016 15:34:29 +0100
    Committer: Ingo Molnar <mingo@kernel.org>
    CommitDate: Thu, 31 Mar 2016 10:30:45 +0200

    ftrace/perf: Check sample types only for sampling events

    Currently we check sample type for ftrace:function events
    even if it's not created as a sampling event. That prevents
    creating ftrace_function event in counting mode.

    Make sure we check sample types only for sampling events.

    Before:
    $ sudo perf stat -e ftrace:function ls
    ...

    Performance counter stats for 'ls':

    <not supported> ftrace:function

    0.001983662 seconds time elapsed

    After:
    $ sudo perf stat -e ftrace:function ls
    ...

    Performance counter stats for 'ls':

    44,498 ftrace:function

    0.037534722 seconds time elapsed

    Suggested-by: Namhyung Kim <namhyung@kernel.org>
    Signed-off-by: Jiri Olsa <jolsa@kernel.org>
    Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
    Acked-by: Steven Rostedt <rostedt@goodmis.org>
    Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
    Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
    Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
    Cc: Jiri Olsa <jolsa@redhat.com>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Stephane Eranian <eranian@google.com>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: Vince Weaver <vincent.weaver@maine.edu>
    Link: http://lkml.kernel.org/r/1458138873-1553-2-git-send-email-jolsa@kernel.org
    Signed-off-by: Ingo Molnar <mingo@kernel.org>
    ---
    kernel/trace/trace_event_perf.c | 3 +++
    1 file changed, 3 insertions(+)

    diff --git a/kernel/trace/trace_event_perf.c b/kernel/trace/trace_event_perf.c
    index 00df25f..e11108f 100644
    --- a/kernel/trace/trace_event_perf.c
    +++ b/kernel/trace/trace_event_perf.c
    @@ -47,6 +47,9 @@ static int perf_trace_event_perm(struct trace_event_call *tp_event,
    if (perf_paranoid_tracepoint_raw() && !capable(CAP_SYS_ADMIN))
    return -EPERM;

    + if (!is_sampling_event(p_event))
    + return 0;
    +
    /*
    * We don't allow user space callchains for function trace
    * event, due to issues with page faults while tracing page
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      Last update: 2016-03-31 11:41    [W:2.387 / U:0.008 seconds]
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