linux-kernel - [PATCH v4 2/2] perf parse: Copy string to perf_evsel_config

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Message-Id: <20200108142010.11269-2-leo.yan@linaro.org>
Date:   Wed,  8 Jan 2020 22:20:10 +0800
From:   Leo Yan <leo.yan@...aro.org>
To:     Arnaldo Carvalho de Melo <acme@...hat.com>,
        Jiri Olsa <jolsa@...nel.org>,
        Mathieu Poirier <mathieu.poirier@...aro.org>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Ian Rogers <irogers@...gle.com>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Andi Kleen <ak@...ux.intel.com>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Mike Leach <mike.leach@...aro.org>
Cc:     Leo Yan <leo.yan@...aro.org>
Subject: [PATCH v4 2/2] perf parse: Copy string to perf_evsel_config_term

perf with CoreSight fails to record trace data with command:

  perf record -e cs_etm/@..._etr0/u --per-thread ls
  failed to set sink "" on event cs_etm/@..._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@...nel.org>
Signed-off-by: Leo Yan <leo.yan@...aro.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