Merge branch 'jk/lsan-race-ignore-false-positive'

CI jobs that run threaded programs under LSan has been giving false
positives from time to time, which has been worked around.

This is an alternative to the jk/lsan-race-with-barrier topic with
much smaller change to the production code.

* jk/lsan-race-ignore-false-positive:
  test-lib: ignore leaks in the sanitizer's thread code
  test-lib: check leak logs for presence of DEDUP_TOKEN
  test-lib: simplify leak-log checking
  test-lib: rely on logs to detect leaks
  Revert barrier-based LSan threading race workaround

Author: gitster

Makefile

@@ -141,10 +141,6 @@ include shared.mak
 #
 # Define NO_PTHREADS if you do not have or do not want to use Pthreads.
 #
-# Define THREAD_BARRIER_PTHREAD if your system has pthread_barrier_t. Barrier
-# support is optional and is only helpful when building with SANITIZE=leak, as
-# it is used to eliminate some races in the leak-checker.
-#
 # Define NO_PREAD if you have a problem with pread() system call (e.g.
 # cygwin1.dll before v1.5.22).
 #
@@ -2083,9 +2079,6 @@ ifdef NO_PTHREADS
 else
 	BASIC_CFLAGS += $(PTHREAD_CFLAGS)
 	EXTLIBS += $(PTHREAD_LIBS)
-	ifdef THREAD_BARRIER_PTHREAD
-		BASIC_CFLAGS += -DTHREAD_BARRIER_PTHREAD
-	endif
 endif
 
 ifdef HAVE_PATHS_H

builtin/grep.c

@@ -101,9 +101,6 @@ static pthread_cond_t cond_write;
 /* Signalled when we are finished with everything. */
 static pthread_cond_t cond_result;
 
-/* Synchronize the start of all threads */
-static maybe_thread_barrier_t start_barrier;
-
 static int skip_first_line;
 
 static void add_work(struct grep_opt *opt, struct grep_source *gs)
@@ -201,8 +198,6 @@ static void *run(void *arg)
 	int hit = 0;
 	struct grep_opt *opt = arg;
 
-	maybe_thread_barrier_wait(&start_barrier);
-
 	while (1) {
 		struct work_item *w = get_work();
 		if (!w)
@@ -234,7 +229,6 @@ static void start_threads(struct grep_opt *opt)
 	pthread_cond_init(&cond_add, NULL);
 	pthread_cond_init(&cond_write, NULL);
 	pthread_cond_init(&cond_result, NULL);
-	maybe_thread_barrier_init(&start_barrier, NULL, num_threads + 1);
 	grep_use_locks = 1;
 	enable_obj_read_lock();
 
@@ -254,7 +248,6 @@ static void start_threads(struct grep_opt *opt)
 			die(_("grep: failed to create thread: %s"),
 			    strerror(err));
 	}
-	maybe_thread_barrier_wait(&start_barrier);
 }
 
 static int wait_all(void)
@@ -291,7 +284,6 @@ static int wait_all(void)
 	pthread_cond_destroy(&cond_add);
 	pthread_cond_destroy(&cond_write);
 	pthread_cond_destroy(&cond_result);
-	maybe_thread_barrier_destroy(&start_barrier);
 	grep_use_locks = 0;
 	disable_obj_read_lock();
 

builtin/index-pack.c

@@ -185,8 +185,6 @@ static pthread_mutex_t deepest_delta_mutex;
 
 static pthread_key_t key;
 
-static maybe_thread_barrier_t start_barrier;
-
 static inline void lock_mutex(pthread_mutex_t *mutex)
 {
 	if (threads_active)
@@ -211,7 +209,6 @@ static void init_thread(void)
 	if (show_stat)
 		pthread_mutex_init(&deepest_delta_mutex, NULL);
 	pthread_key_create(&key, NULL);
-	maybe_thread_barrier_init(&start_barrier, NULL, nr_threads);
 	CALLOC_ARRAY(thread_data, nr_threads);
 	for (i = 0; i < nr_threads; i++) {
 		thread_data[i].pack_fd = xopen(curr_pack, O_RDONLY);
@@ -234,7 +231,6 @@ static void cleanup_thread(void)
 	for (i = 0; i < nr_threads; i++)
 		close(thread_data[i].pack_fd);
 	pthread_key_delete(key);
-	maybe_thread_barrier_destroy(&start_barrier);
 	free(thread_data);
 }
 
@@ -1104,8 +1100,6 @@ static int compare_ref_delta_entry(const void *a, const void *b)
 
 static void *threaded_second_pass(void *data)
 {
-	if (threads_active)
-		maybe_thread_barrier_wait(&start_barrier);
 	if (data)
 		set_thread_data(data);
 	for (;;) {

ci/lib.sh

@@ -385,7 +385,6 @@ linux-musl)
 	;;
 linux-leaks|linux-reftable-leaks)
 	export SANITIZE=leak
-	export THREAD_BARRIER_PTHREAD=1
 	;;
 linux-asan-ubsan)
 	export SANITIZE=address,undefined

t/test-lib.sh

@@ -80,6 +80,7 @@ prepend_var ASAN_OPTIONS : detect_leaks=0
 export ASAN_OPTIONS
 
 prepend_var LSAN_OPTIONS : $GIT_SAN_OPTIONS
+prepend_var LSAN_OPTIONS : exitcode=0
 prepend_var LSAN_OPTIONS : fast_unwind_on_malloc=0
 export LSAN_OPTIONS
 
@@ -339,17 +340,6 @@ case "$TRASH_DIRECTORY" in
  *) TRASH_DIRECTORY="$TEST_OUTPUT_DIRECTORY/$TRASH_DIRECTORY" ;;
 esac
 
-# Utility functions using $TEST_RESULTS_* variables
-nr_san_dir_leaks_ () {
-	# stderr piped to /dev/null because the directory may have
-	# been "rmdir"'d already.
-	find "$TEST_RESULTS_SAN_DIR" \
-		-type f \
-		-name "$TEST_RESULTS_SAN_FILE_PFX.*" 2>/dev/null |
-	xargs grep -lv "Unable to get registers from thread" |
-	wc -l
-}
-
 # If --stress was passed, run this test repeatedly in several parallel loops.
 if test "$GIT_TEST_STRESS_STARTED" = "done"
 then
@@ -1180,8 +1170,15 @@ test_atexit_handler () {
 }
 
 check_test_results_san_file_empty_ () {
-	test -z "$TEST_RESULTS_SAN_FILE" ||
-	test "$(nr_san_dir_leaks_)" = 0
+	test -z "$TEST_RESULTS_SAN_FILE" && return 0
+
+	# stderr piped to /dev/null because the directory may have
+	# been "rmdir"'d already.
+	! find "$TEST_RESULTS_SAN_DIR" \
+		-type f \
+		-name "$TEST_RESULTS_SAN_FILE_PFX.*" 2>/dev/null |
+	xargs grep ^DEDUP_TOKEN |
+	grep -qv sanitizer::GetThreadStackTopAndBottom
 }
 
 check_test_results_san_file_ () {

thread-utils.h

@@ -53,22 +53,5 @@ int dummy_pthread_init(void *);
 int online_cpus(void);
 int init_recursive_mutex(pthread_mutex_t*);
 
-#ifdef THREAD_BARRIER_PTHREAD
-#define maybe_thread_barrier_t pthread_barrier_t
-#define maybe_thread_barrier_init pthread_barrier_init
-#define maybe_thread_barrier_wait pthread_barrier_wait
-#define maybe_thread_barrier_destroy pthread_barrier_destroy
-#else
-#define maybe_thread_barrier_t int
-static inline int maybe_thread_barrier_init(maybe_thread_barrier_t *b UNUSED,
-					    void *attr UNUSED,
-					    unsigned nr UNUSED)
-{
-	errno = ENOSYS;
-	return -1;
-}
-#define maybe_thread_barrier_wait(barrier)
-#define maybe_thread_barrier_destroy(barrier)
-#endif
 
 #endif /* THREAD_COMPAT_H */