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

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 */