perf thread_map: Use readdir() instead of deprecated readdir_r()

The readdir() function is thread safe as long as just one thread uses a
DIR, which is the case in thread_map, so, 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-del8h2a0f40z75j4r42l96l0@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 4 insertions, 4 deletions

diff --git a/tools/perf/util/thread_map.c b/tools/perf/util/thread_map.c
index 08afc6909953..267112b4e3db 100644
--- a/tools/perf/util/thread_map.c
+++ b/tools/perf/util/thread_map.c
@@ -94,7 +94,7 @@ struct thread_map *thread_map__new_by_uid(uid_t uid)
         DIR *proc;
         int max_threads = 32, items, i;
         char path[256];
-        struct dirent dirent, *next, **namelist = NULL;
+        struct dirent *dirent, **namelist = NULL;
         struct thread_map *threads = thread_map__alloc(max_threads);
 
         if (threads == NULL)
@@ -107,16 +107,16 @@ struct thread_map *thread_map__new_by_uid(uid_t uid)
         threads->nr = 0;
         atomic_set(&threads->refcnt, 1);
 
-        while (!readdir_r(proc, &dirent, &next) && next) {
+        while ((dirent = readdir(proc)) != NULL) {
                 char *end;
                 bool grow = false;
                 struct stat st;
-                pid_t pid = strtol(dirent.d_name, &end, 10);
+                pid_t pid = strtol(dirent->d_name, &end, 10);
 
                 if (*end) /* only interested in proper numerical dirents */
                         continue;
 
-                snprintf(path, sizeof(path), "/proc/%s", dirent.d_name);
+                snprintf(path, sizeof(path), "/proc/%s", dirent->d_name);
 
                 if (stat(path, &st) != 0)
                         continue;