[PATCH 3.16 357/366] perf tools: Use readdir() instead of deprecated readdir_r()

Ben Hutchings
2018-11-11T20:31:01Z

From: Arnaldo Carvalho de Melo <acme@redhat.com>

commit bfc279f3d233150ff260e9e93012e14f86810648 upstream.

The readdir() function is thread safe as long as just one thread uses a
DIR, which is the case when parsing tracepoint event definitions, to
avoid breaking the build with glibc-2.23.90 (upcoming 2.24), use it
instead of readdir_r().

See: http://man7.org/linux/man-pages/man3/readdir.3.html

"However, in modern implementations (including the glibc implementation),
concurrent calls to readdir() that specify different directory streams
are thread-safe. In cases where multiple threads must read from the
same directory stream, using readdir() with external synchronization is
still preferable to the use of the deprecated readdir_r(3) function."

Noticed while building on a Fedora Rawhide docker container.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-wddn49r6bz6wq4ee3dxbl7lo@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
tools/perf/util/parse-events.c | 60 +++++++++++++++++-----------------
1 file changed, 30 insertions(+), 30 deletions(-)

--- a/tools/perf/util/parse-events.c
+++ b/tools/perf/util/parse-events.c
@@ -123,11 +123,11 @@ static struct event_symbol event_symbols
#define PERF_EVENT_TYPE(config) __PERF_EVENT_FIELD(config, TYPE)
#define PERF_EVENT_ID(config) __PERF_EVENT_FIELD(config, EVENT)

-#define for_each_subsystem(sys_dir, sys_dirent, sys_next) \
- while (!readdir_r(sys_dir, &sys_dirent, &sys_next) && sys_next) \
- if (sys_dirent.d_type == DT_DIR && \
- (strcmp(sys_dirent.d_name, ".")) && \
- (strcmp(sys_dirent.d_name, "..")))
+#define for_each_subsystem(sys_dir, sys_dirent) \
+ while ((sys_dirent = readdir(sys_dir)) != NULL) \
+ if (sys_dirent->d_type == DT_DIR && \
+ (strcmp(sys_dirent->d_name, ".")) && \
+ (strcmp(sys_dirent->d_name, "..")))

static int tp_event_has_id(struct dirent *sys_dir, struct dirent *evt_dir)
{
@@ -144,12 +144,12 @@ static int tp_event_has_id(struct dirent
return 0;
}

-#define for_each_event(sys_dirent, evt_dir, evt_dirent, evt_next) \
- while (!readdir_r(evt_dir, &evt_dirent, &evt_next) && evt_next) \
- if (evt_dirent.d_type == DT_DIR && \
- (strcmp(evt_dirent.d_name, ".")) && \
- (strcmp(evt_dirent.d_name, "..")) && \
- (!tp_event_has_id(&sys_dirent, &evt_dirent)))
+#define for_each_event(sys_dirent, evt_dir, evt_dirent) \
+ while ((evt_dirent = readdir(evt_dir)) != NULL) \
+ if (evt_dirent->d_type == DT_DIR && \
+ (strcmp(evt_dirent->d_name, ".")) && \
+ (strcmp(evt_dirent->d_name, "..")) && \
+ (!tp_event_has_id(sys_dirent, evt_dirent)))

#define MAX_EVENT_LENGTH 512

@@ -158,7 +158,7 @@ struct tracepoint_path *tracepoint_id_to
{
struct tracepoint_path *path = NULL;
DIR *sys_dir, *evt_dir;
- struct dirent *sys_next, *evt_next, sys_dirent, evt_dirent;
+ struct dirent *sys_dirent, *evt_dirent;
char id_buf[24];
int fd;
u64 id;
@@ -172,18 +172,18 @@ struct tracepoint_path *tracepoint_id_to
if (!sys_dir)
return NULL;

- for_each_subsystem(sys_dir, sys_dirent, sys_next) {
+ for_each_subsystem(sys_dir, sys_dirent) {

snprintf(dir_path, MAXPATHLEN, "%s/%s", tracing_events_path,
- sys_dirent.d_name);
+ sys_dirent->d_name);
evt_dir = opendir(dir_path);
if (!evt_dir)
continue;

- for_each_event(sys_dirent, evt_dir, evt_dirent, evt_next) {
+ for_each_event(sys_dirent, evt_dir, evt_dirent) {

snprintf(evt_path, MAXPATHLEN, "%s/%s/id", dir_path,
- evt_dirent.d_name);
+ evt_dirent->d_name);
fd = open(evt_path, O_RDONLY);
if (fd < 0)
continue;
@@ -208,9 +208,9 @@ struct tracepoint_path *tracepoint_id_to
free(path);
return NULL;
}
- strncpy(path->system, sys_dirent.d_name,
+ strncpy(path->system, sys_dirent->d_name,
MAX_EVENT_LENGTH);
- strncpy(path->name, evt_dirent.d_name,
+ strncpy(path->name, evt_dirent->d_name,
MAX_EVENT_LENGTH);
return path;
}
@@ -1003,7 +1003,7 @@ void print_tracepoint_events(const char
bool name_only)
{
DIR *sys_dir, *evt_dir;
- struct dirent *sys_next, *evt_next, sys_dirent, evt_dirent;
+ struct dirent *sys_dirent, *evt_dirent;
char evt_path[MAXPATHLEN];
char dir_path[MAXPATHLEN];

@@ -1016,29 +1016,29 @@ void print_tracepoint_events(const char
if (!sys_dir)
return;

- for_each_subsystem(sys_dir, sys_dirent, sys_next) {
+ for_each_subsystem(sys_dir, sys_dirent) {
if (subsys_glob != NULL &&
- !strglobmatch(sys_dirent.d_name, subsys_glob))
+ !strglobmatch(sys_dirent->d_name, subsys_glob))
continue;

snprintf(dir_path, MAXPATHLEN, "%s/%s", tracing_events_path,
- sys_dirent.d_name);
+ sys_dirent->d_name);
evt_dir = opendir(dir_path);
if (!evt_dir)
continue;

- for_each_event(sys_dirent, evt_dir, evt_dirent, evt_next) {
+ for_each_event(sys_dirent, evt_dir, evt_dirent) {
if (event_glob != NULL &&
- !strglobmatch(evt_dirent.d_name, event_glob))
+ !strglobmatch(evt_dirent->d_name, event_glob))
continue;

if (name_only) {
- printf("%s:%s ", sys_dirent.d_name, evt_dirent.d_name);
+ printf("%s:%s ", sys_dirent->d_name, evt_dirent->d_name);
continue;
}

snprintf(evt_path, MAXPATHLEN, "%s:%s",
- sys_dirent.d_name, evt_dirent.d_name);
+ sys_dirent->d_name, evt_dirent->d_name);
printf(" %-50s [%s]\n", evt_path,
event_type_descriptors[PERF_TYPE_TRACEPOINT]);
}
@@ -1054,7 +1054,7 @@ void print_tracepoint_events(const char
int is_valid_tracepoint(const char *event_string)
{
DIR *sys_dir, *evt_dir;
- struct dirent *sys_next, *evt_next, sys_dirent, evt_dirent;
+ struct dirent *sys_dirent, *evt_dirent;
char evt_path[MAXPATHLEN];
char dir_path[MAXPATHLEN];

@@ -1065,17 +1065,17 @@ int is_valid_tracepoint(const char *even
if (!sys_dir)
return 0;

- for_each_subsystem(sys_dir, sys_dirent, sys_next) {
+ for_each_subsystem(sys_dir, sys_dirent) {

snprintf(dir_path, MAXPATHLEN, "%s/%s", tracing_events_path,
- sys_dirent.d_name);
+ sys_dirent->d_name);
evt_dir = opendir(dir_path);
if (!evt_dir)
continue;

- for_each_event(sys_dirent, evt_dir, evt_dirent, evt_next) {
+ for_each_event(sys_dirent, evt_dir, evt_dirent) {
snprintf(evt_path, MAXPATHLEN, "%s:%s",
- sys_dirent.d_name, evt_dirent.d_name);
+ sys_dirent->d_name, evt_dirent->d_name);
if (!strcmp(evt_path, event_string)) {
closedir(evt_dir);
closedir(sys_dir);