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    Subject[PATCH v4 2/2] perf parse: Copy string to perf_evsel_config_term
    Date
    perf with CoreSight fails to record trace data with command:

    perf record -e cs_etm/@tmc_etr0/u --per-thread ls
    failed to set sink "" on event cs_etm/@tmc_etr0/u with 21 (Is a
    directory)/perf/

    This failure is root caused with the commit 1dc925568f01 ("perf
    parse: Add a deep delete for parse event terms").

    The log shows, cs_etm fails to parse the sink attribution; cs_etm event
    relies on the event configuration to pass sink name, but the event
    specific configuration data cannot be passed properly with flow:

    get_config_terms()
    ADD_CONFIG_TERM(DRV_CFG, term->val.str);
    __t->val.str = term->val.str;
    `> __t->val.str is assigned to term->val.str;

    parse_events_terms__purge()
    parse_events_term__delete()
    zfree(&term->val.str);
    `> term->val.str is freed and assigned to NULL pointer;

    cs_etm_set_sink_attr()
    sink = __t->val.str;
    `> sink string has been freed.

    To fix this issue, in the function get_config_terms(), this patch
    changes to use strdup() for allocation a new duplicate string rather
    than directly assignment string pointer.

    This patch addes a new field 'free_str' in the data structure
    perf_evsel_config_term; 'free_str' is set to true when the union is used
    as a string pointer; thus it can tell perf_evsel__free_config_terms() to
    free the string.

    Fixes: 1dc925568f01 ("perf parse: Add a deep delete for parse event terms")
    Suggested-by: Jiri Olsa <jolsa@kernel.org>
    Signed-off-by: Leo Yan <leo.yan@linaro.org>
    ---
    tools/perf/util/evsel.c | 2 ++
    tools/perf/util/evsel_config.h | 1 +
    tools/perf/util/parse-events.c | 7 ++++++-
    3 files changed, 9 insertions(+), 1 deletion(-)

    diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
    index 5f27f6b7ed94..6b56b35876e7 100644
    --- a/tools/perf/util/evsel.c
    +++ b/tools/perf/util/evsel.c
    @@ -1265,6 +1265,8 @@ static void perf_evsel__free_config_terms(struct evsel *evsel)

    list_for_each_entry_safe(term, h, &evsel->config_terms, list) {
    list_del_init(&term->list);
    + if (term->free_str)
    + free(term->val.str);
    free(term);
    }
    }
    diff --git a/tools/perf/util/evsel_config.h b/tools/perf/util/evsel_config.h
    index 4e5b3ebf09cf..12af1bca0cad 100644
    --- a/tools/perf/util/evsel_config.h
    +++ b/tools/perf/util/evsel_config.h
    @@ -32,6 +32,7 @@ enum evsel_term_type {
    struct perf_evsel_config_term {
    struct list_head list;
    enum evsel_term_type type;
    + bool free_str;
    union {
    u64 num;
    char *str;
    diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
    index caf38518762f..3353e9e8b134 100644
    --- a/tools/perf/util/parse-events.c
    +++ b/tools/perf/util/parse-events.c
    @@ -1240,7 +1240,12 @@ do { \
    #define ADD_CONFIG_TERM_STR(__type, __val) \
    do { \
    ADD_CONFIG_TERM(__type); \
    - __t->val.str = __val; \
    + __t->val.str = strdup(__val); \
    + if (!__t->val.str) { \
    + zfree(&__t); \
    + return -ENOMEM; \
    + } \
    + __t->free_str = true; \
    } while (0)

    struct parse_events_term *term;
    --
    2.17.1
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