perf parse events: Demystify memory allocations

List heads are currently allocated way down the function chain in
__add_event and add_tracepoint and then freed when the scanner code
calls parse_events_update_lists.

Be more explicit with where memory is allocated and who should free it. With
this patch the list_head is allocated in the scanner code and freed when the
scanner code calls parse_events_update_lists.

Signed-off-by: David Ahern <dsahern@gmail.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1372793245-4136-7-git-send-email-dsahern@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 16 insertions, 36 deletions

diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
index bcf83ee97e92..e85376999efc 100644
--- a/tools/perf/util/parse-events.c
+++ b/tools/perf/util/parse-events.c
@@ -264,40 +264,29 @@ const char *event_type(int type)
 
 
 
-static int __add_event(struct list_head **_list, int *idx,
+static int __add_event(struct list_head *list, int *idx,
 		       struct perf_event_attr *attr,
 		       char *name, struct cpu_map *cpus)
 {
 	struct perf_evsel *evsel;
-	struct list_head *list = *_list;
-
-	if (!list) {
-		list = malloc(sizeof(*list));
-		if (!list)
-			return -ENOMEM;
-		INIT_LIST_HEAD(list);
-	}
 
 	event_attr_init(attr);
 
 	evsel = perf_evsel__new(attr, (*idx)++);
-	if (!evsel) {
-		free(list);
+	if (!evsel)
 		return -ENOMEM;
-	}
 
 	evsel->cpus = cpus;
 	if (name)
 		evsel->name = strdup(name);
 	list_add_tail(&evsel->node, list);
-	*_list = list;
 	return 0;
 }
 
-static int add_event(struct list_head **_list, int *idx,
+static int add_event(struct list_head *list, int *idx,
 		     struct perf_event_attr *attr, char *name)
 {
-	return __add_event(_list, idx, attr, name, NULL);
+	return __add_event(list, idx, attr, name, NULL);
 }
 
 static int parse_aliases(char *str, const char *names[][PERF_EVSEL__MAX_ALIASES], int size)
@@ -318,7 +307,7 @@ static int parse_aliases(char *str, const char *names[][PERF_EVSEL__MAX_ALIASES]
 	return -1;
 }
 
-int parse_events_add_cache(struct list_head **list, int *idx,
+int parse_events_add_cache(struct list_head *list, int *idx,
 			   char *type, char *op_result1, char *op_result2)
 {
 	struct perf_event_attr attr;
@@ -379,31 +368,21 @@ int parse_events_add_cache(struct list_head **list, int *idx,
 	return add_event(list, idx, &attr, name);
 }
 
-static int add_tracepoint(struct list_head **listp, int *idx,
+static int add_tracepoint(struct list_head *list, int *idx,
 			  char *sys_name, char *evt_name)
 {
 	struct perf_evsel *evsel;
-	struct list_head *list = *listp;
-
-	if (!list) {
-		list = malloc(sizeof(*list));
-		if (!list)
-			return -ENOMEM;
-		INIT_LIST_HEAD(list);
-	}
 
 	evsel = perf_evsel__newtp(sys_name, evt_name, (*idx)++);
-	if (!evsel) {
-		free(list);
+	if (!evsel)
 		return -ENOMEM;
-	}
 
 	list_add_tail(&evsel->node, list);
-	*listp = list;
+
 	return 0;
 }
 
-static int add_tracepoint_multi_event(struct list_head **list, int *idx,
+static int add_tracepoint_multi_event(struct list_head *list, int *idx,
 				      char *sys_name, char *evt_name)
 {
 	char evt_path[MAXPATHLEN];
@@ -435,7 +414,7 @@ static int add_tracepoint_multi_event(struct list_head **list, int *idx,
 	return ret;
 }
 
-static int add_tracepoint_event(struct list_head **list, int *idx,
+static int add_tracepoint_event(struct list_head *list, int *idx,
 				char *sys_name, char *evt_name)
 {
 	return strpbrk(evt_name, "*?") ?
@@ -443,7 +422,7 @@ static int add_tracepoint_event(struct list_head **list, int *idx,
 	       add_tracepoint(list, idx, sys_name, evt_name);
 }
 
-static int add_tracepoint_multi_sys(struct list_head **list, int *idx,
+static int add_tracepoint_multi_sys(struct list_head *list, int *idx,
 				    char *sys_name, char *evt_name)
 {
 	struct dirent *events_ent;
@@ -475,7 +454,7 @@ static int add_tracepoint_multi_sys(struct list_head **list, int *idx,
 	return ret;
 }
 
-int parse_events_add_tracepoint(struct list_head **list, int *idx,
+int parse_events_add_tracepoint(struct list_head *list, int *idx,
 				char *sys, char *event)
 {
 	int ret;
@@ -530,7 +509,7 @@ do {					\
 	return 0;
 }
 
-int parse_events_add_breakpoint(struct list_head **list, int *idx,
+int parse_events_add_breakpoint(struct list_head *list, int *idx,
 				void *ptr, char *type)
 {
 	struct perf_event_attr attr;
@@ -611,7 +590,7 @@ static int config_attr(struct perf_event_attr *attr,
 	return 0;
 }
 
-int parse_events_add_numeric(struct list_head **list, int *idx,
+int parse_events_add_numeric(struct list_head *list, int *idx,
 			     u32 type, u64 config,
 			     struct list_head *head_config)
 {
@@ -644,7 +623,7 @@ static char *pmu_event_name(struct list_head *head_terms)
 	return NULL;
 }
 
-int parse_events_add_pmu(struct list_head **list, int *idx,
+int parse_events_add_pmu(struct list_head *list, int *idx,
 			 char *name, struct list_head *head_config)
 {
 	struct perf_event_attr attr;
@@ -687,6 +666,7 @@ void parse_events__set_leader(char *name, struct list_head *list)
 	leader->group_name = name ? strdup(name) : NULL;
 }
 
+/* list_event is assumed to point to malloc'ed memory */
 void parse_events_update_lists(struct list_head *list_event,
 			       struct list_head *list_all)
 {