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    Subject[PATCH 28/30] perf evsel: Provide a new constructor for tracepoints
    Date
    From: Arnaldo Carvalho de Melo <acme@redhat.com>

    The existing constructor receives a perf_event_attr filled with the
    event type and the config.

    To reduce the boilerplate for tracepoints, provide a new constructor,
    perf_evsel__newtp() that receives the tracepoint name and will open
    the debugfs file, call into libtraceevent new pevent_parse_format file
    to fill its ->tp_format member, so that users can then just call
    perf_evsel__field() to access its fields.

    Cc: David Ahern <dsahern@gmail.com>
    Cc: Frederic Weisbecker <fweisbec@gmail.com>
    Cc: Jiri Olsa <jolsa@redhat.com>
    Cc: Mike Galbraith <efault@gmx.de>
    Cc: Namhyung Kim <namhyung@gmail.com>
    Cc: Paul Mackerras <paulus@samba.org>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Stephane Eranian <eranian@google.com>
    Cc: Steven Rostedt <rostedt@goodmis.org>
    Link: http://lkml.kernel.org/n/tip-6du8dl1hz0y5l4cybodye7hn@git.kernel.org
    Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
    ---
    tools/perf/util/evsel.c | 88 +++++++++++++++++++++++++++++++++++++++++++---
    tools/perf/util/evsel.h | 5 +++
    2 files changed, 87 insertions(+), 6 deletions(-)

    diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
    index 1506ba0..00936ad 100644
    --- a/tools/perf/util/evsel.c
    +++ b/tools/perf/util/evsel.c
    @@ -10,6 +10,7 @@
    #include <byteswap.h>
    #include <linux/bitops.h>
    #include "asm/bug.h"
    +#include "debugfs.h"
    #include "event-parse.h"
    #include "evsel.h"
    #include "evlist.h"
    @@ -69,6 +70,72 @@ struct perf_evsel *perf_evsel__new(struct perf_event_attr *attr, int idx)
    return evsel;
    }

    +static struct event_format *event_format__new(const char *sys, const char *name)
    +{
    + int fd, n;
    + char *filename;
    + void *bf = NULL, *nbf;
    + size_t size = 0, alloc_size = 0;
    + struct event_format *format = NULL;
    +
    + if (asprintf(&filename, "%s/%s/%s/format", tracing_events_path, sys, name) < 0)
    + goto out;
    +
    + fd = open(filename, O_RDONLY);
    + if (fd < 0)
    + goto out_free_filename;
    +
    + do {
    + if (size == alloc_size) {
    + alloc_size += BUFSIZ;
    + nbf = realloc(bf, alloc_size);
    + if (nbf == NULL)
    + goto out_free_bf;
    + bf = nbf;
    + }
    +
    + n = read(fd, bf + size, BUFSIZ);
    + if (n < 0)
    + goto out_free_bf;
    + size += n;
    + } while (n > 0);
    +
    + pevent_parse_format(&format, bf, size, sys);
    +
    +out_free_bf:
    + free(bf);
    + close(fd);
    +out_free_filename:
    + free(filename);
    +out:
    + return format;
    +}
    +
    +struct perf_evsel *perf_evsel__newtp(const char *sys, const char *name, int idx)
    +{
    + struct perf_evsel *evsel = zalloc(sizeof(*evsel));
    +
    + if (evsel != NULL) {
    + struct perf_event_attr attr = {
    + .type = PERF_TYPE_TRACEPOINT,
    + };
    +
    + evsel->tp_format = event_format__new(sys, name);
    + if (evsel->tp_format == NULL)
    + goto out_free;
    +
    + attr.config = evsel->tp_format->id;
    + perf_evsel__init(evsel, &attr, idx);
    + evsel->name = evsel->tp_format->name;
    + }
    +
    + return evsel;
    +
    +out_free:
    + free(evsel);
    + return NULL;
    +}
    +
    const char *perf_evsel__hw_names[PERF_COUNT_HW_MAX] = {
    "cycles",
    "instructions",
    @@ -495,6 +562,10 @@ void perf_evsel__delete(struct perf_evsel *evsel)
    perf_evsel__exit(evsel);
    close_cgroup(evsel->cgrp);
    free(evsel->group_name);
    + if (evsel->tp_format && evsel->name == evsel->tp_format->name) {
    + evsel->name = NULL;
    + pevent_free_format(evsel->tp_format);
    + }
    free(evsel->name);
    free(evsel);
    }
    @@ -1002,14 +1073,19 @@ int perf_event__synthesize_sample(union perf_event *event, u64 type,
    return 0;
    }

    +struct format_field *perf_evsel__field(struct perf_evsel *evsel, const char *name)
    +{
    + return pevent_find_field(evsel->tp_format, name);
    +}
    +
    char *perf_evsel__strval(struct perf_evsel *evsel, struct perf_sample *sample,
    const char *name)
    {
    - struct format_field *field = pevent_find_field(evsel->tp_format, name);
    + struct format_field *field = perf_evsel__field(evsel, name);
    int offset;

    - if (!field)
    - return NULL;
    + if (!field)
    + return NULL;

    offset = field->offset;

    @@ -1024,11 +1100,11 @@ char *perf_evsel__strval(struct perf_evsel *evsel, struct perf_sample *sample,
    u64 perf_evsel__intval(struct perf_evsel *evsel, struct perf_sample *sample,
    const char *name)
    {
    - struct format_field *field = pevent_find_field(evsel->tp_format, name);
    + struct format_field *field = perf_evsel__field(evsel, name);
    u64 val;

    - if (!field)
    - return 0;
    + if (!field)
    + return 0;

    val = pevent_read_number(evsel->tp_format->pevent,
    sample->raw_data + field->offset, field->size);
    diff --git a/tools/perf/util/evsel.h b/tools/perf/util/evsel.h
    index 93876ba..bb445d1 100644
    --- a/tools/perf/util/evsel.h
    +++ b/tools/perf/util/evsel.h
    @@ -81,6 +81,7 @@ struct perf_evlist;
    struct perf_record_opts;

    struct perf_evsel *perf_evsel__new(struct perf_event_attr *attr, int idx);
    +struct perf_evsel *perf_evsel__newtp(const char *sys, const char *name, int idx);
    void perf_evsel__init(struct perf_evsel *evsel,
    struct perf_event_attr *attr, int idx);
    void perf_evsel__exit(struct perf_evsel *evsel);
    @@ -128,6 +129,10 @@ char *perf_evsel__strval(struct perf_evsel *evsel, struct perf_sample *sample,
    u64 perf_evsel__intval(struct perf_evsel *evsel, struct perf_sample *sample,
    const char *name);

    +struct format_field;
    +
    +struct format_field *perf_evsel__field(struct perf_evsel *evsel, const char *name);
    +
    #define perf_evsel__match(evsel, t, c) \
    (evsel->attr.type == PERF_TYPE_##t && \
    evsel->attr.config == PERF_COUNT_##c)
    --
    1.7.1


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