[PATCH v4 2/2] perf parse: Copy string to perf_evsel_config_term

Leo Yan
2020-01-08T14:20:57Z

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