Add more coordination between the watchdog thread and the test thread.
This is to resolve the racing betwen the watchdog failure reporting and test iterations.
PiperOrigin-RevId: 854343112
diff --git a/centipede/runner.cc b/centipede/runner.cc
index d47b2f2..fbf5a2b 100644
--- a/centipede/runner.cc
+++ b/centipede/runner.cc
@@ -48,6 +48,7 @@
#include <vector>
#include "absl/base/nullability.h"
+#include "absl/base/optimization.h"
#include "./centipede/byte_array_mutator.h"
#include "./centipede/dispatcher_flag_helper.h"
#include "./centipede/execution_metadata.h"
@@ -99,6 +100,26 @@
return tv.tv_sec * kUsecInSec + tv.tv_usec;
}
+// Atomic flags to make sure that (a) watchdog failure is reported only for
+// the current input, and (b) only one thread is handling watchdog failures.
+
+// True if the watchdog thread is detecting failures, false otherwise.
+static std::atomic<bool> watchdog_thread_busy = false;
+// True if a watchdog failure is found, false otherwise.
+static std::atomic<bool> watchdog_failure_found = false;
+
+static void WaitWatchdogThreadIdle() {
+ while (ABSL_PREDICT_FALSE(watchdog_thread_busy.load())) {
+ if (ABSL_PREDICT_FALSE(watchdog_failure_found.load())) {
+ // A failure is found - wait for the process to terminate.
+ sleep(1); // NOLINT
+ } else {
+ // Busy-wait for the detection.
+ sleep(0); // NOLINT
+ }
+ }
+}
+
static void CheckWatchdogLimits() {
const uint64_t curr_time = time(nullptr);
struct Resource {
@@ -142,11 +163,7 @@
};
for (const auto &resource : resources) {
if (resource.limit != 0 && resource.value > resource.limit) {
- // Allow only one invocation to handle a failure: needed because we call
- // this function periodically in `WatchdogThread()`, but also call it in
- // `RunOneInput()` after all the work is done.
- static std::atomic<bool> already_handling_failure = false;
- if (!already_handling_failure.exchange(true)) {
+ if (!watchdog_failure_found.exchange(true)) {
if (resource.ignore_report) {
fprintf(stderr,
"========= %s exceeded: %" PRIu64 " > %" PRIu64
@@ -192,7 +209,9 @@
// No calls to ResetInputTimer() yet: input execution hasn't started.
if (state->input_start_time == 0) continue;
+ watchdog_thread_busy = true;
CheckWatchdogLimits();
+ watchdog_thread_busy = false;
}
}
@@ -376,6 +395,7 @@
if (fuzztest::internal::state->input_start_time.exchange(0) != 0) {
PostProcessSancov(target_return_value == -1);
}
+ WaitWatchdogThreadIdle();
state->stats.post_time_usec = UsecSinceLast();
state->stats.peak_rss_mb = GetPeakRSSMb();
}
