Commit 2515e614 authored Apr 08, 2016 by Arnaldo Carvalho de Melo

perf tools: 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 when synthesizing events for pre-existing threads
by traversing /proc, 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       /tmp/build/perf/util/event.o
  util/event.c: In function '__event__synthesize_thread':
  util/event.c:466:2: error: 'readdir_r' is deprecated [-Werror=deprecated-declarations]
    while (!readdir_r(tasks, &dirent, &next) && next) {
    ^~~~~
  In file included from /usr/include/features.h:368:0,
                   from /usr/include/stdint.h:25,
                   from /usr/lib/gcc/x86_64-redhat-linux/6.0.0/include/stdint.h:9,
                   from /git/linux/tools/include/linux/types.h:6,
                   from util/event.c:1:
  /usr/include/dirent.h:189:12: note: declared here

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-i1vj7nyjp2p750rirxgrfd3c@git.kernel.org


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

parent 9f448cd3

tools/perf/util/event.c

+6 −6

Original line number	Diff line number	Diff line
		@@ -433,7 +433,7 @@ static int __event__synthesize_thread(union perf_event *comm_event,
		{
		char filename[PATH_MAX];
		DIR *tasks;
		struct dirent dirent, *next;
		struct dirent *dirent;
		pid_t tgid, ppid;
		int rc = 0;

		@@ -462,11 +462,11 @@ static int __event__synthesize_thread(union perf_event *comm_event,
		return 0;
		}

		while (!readdir_r(tasks, &dirent, &next) && next) {
		while ((dirent = readdir(tasks)) != NULL) {
		char *end;
		pid_t _pid;

		_pid = strtol(dirent.d_name, &end, 10);
		_pid = strtol(dirent->d_name, &end, 10);
		if (*end)
		continue;

		@@ -575,7 +575,7 @@ int perf_event__synthesize_threads(struct perf_tool *tool,
		{
		DIR *proc;
		char proc_path[PATH_MAX];
		struct dirent dirent, *next;
		struct dirent *dirent;
		union perf_event comm_event, mmap_event, *fork_event;
		int err = -1;

		@@ -600,9 +600,9 @@ int perf_event__synthesize_threads(struct perf_tool *tool,
		if (proc == NULL)
		goto out_free_fork;

		while (!readdir_r(proc, &dirent, &next) && next) {
		while ((dirent = readdir(proc)) != NULL) {
		char *end;
		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;