Commit 510e5287 authored by Ian Rogers's avatar Ian Rogers Committed by Namhyung Kim
Browse files

perf thread_map: Skip exited threads when scanning /proc 



Scanning /proc is inherently racy. Scanning /proc/pid/task within that
is also racy as the pid can terminate. Rather than failing in
__thread_map__new_all_cpus, skip pids for such failures.

Signed-off-by: default avatarIan Rogers <irogers@google.com>
Cc: James Clark <james.clark@arm.com>
Cc: Justin Stitt <justinstitt@google.com>
Cc: Bill Wendling <morbo@google.com>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Yang Jihong <yangjihong1@huawei.com>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Athira Jajeev <atrajeev@linux.vnet.ibm.com>
Cc: llvm@lists.linux.dev
Signed-off-by: default avatarNamhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/r/20240221034155.1500118-2-irogers@google.com
parent b6968f9b

tools/perf/util/thread_map.c

+4 −5
Original line number Diff line number Diff line
@@ -109,9 +109,10 @@ static struct perf_thread_map *__thread_map__new_all_cpus(uid_t uid) 


		snprintf(path, sizeof(path), "/proc/%d/task", pid);

		items = scandir(path, &namelist, filter, NULL);

		if (items <= 0)

			goto out_free_closedir;



		if (items <= 0) {

			pr_debug("scandir for %d returned empty, skipping\n", pid);

			continue;

		}

		while (threads->nr + items >= max_threads) {

			max_threads *= 2;

			grow = true;
@@ -152,8 +153,6 @@ static struct perf_thread_map *__thread_map__new_all_cpus(uid_t uid) 
	for (i = 0; i < items; i++)

		zfree(&namelist[i]);

	free(namelist);



out_free_closedir:

	zfree(&threads);

	goto out_closedir;

}