[TSan] Add a runtime flag to print full thread creation stacks up to the main thread

[Enna1]

Summary

Currently, we only print how threads involved in data race are created from their parent threads.
Add a runtime flag 'print_full_thread_history' to print thread creation stacks for the threads involved in the data race and their ancestors up to the main thread.

[dvyukov]

clang-format: please reformat the code

Please also fix clang-format warnings.

compiler-rt/lib/tsan/rtl/tsan_flags.inc

84

Asan has print_full_thread_history flag, use the same name.

compiler-rt/lib/tsan/rtl/tsan_rtl_report.cpp

837

Can't this be done in 1 loop and w/o worklist?
Just iterating over all threads and then taking and adding parents until we reach main thread.

compiler-rt/test/tsan/report_full_thread_create_stack.cpp

41 ↗

(On Diff #416902)

Please add actual thread numbers. They must be stable, right.

[Enna1]

Address review comments. PTAL, thanks!

[dvyukov]

compiler-rt/lib/tsan/rtl/tsan_rtl_report.cpp

830

Humm... It looks like it's doing a different thing now as compared to the previous version (add one vs all parents). What is the intended behavior? If the current version is wrong, please extend the test to catch it.
I expected to see something along the following lines:

Tid tid = rep_desc->threads[i]->parent_tid;
while (tid != tid == kMainTid && tid != kInvalidTid) {
  rep.AddThread(tid);
  tid = ctx->thread_registry.GetThreadLocked(tid)->parent;
}

[Enna1]

compiler-rt/lib/tsan/rtl/tsan_rtl_report.cpp

830

emm, I think the code of this version does the same thing as the previous version?
rep_desc->threads.Size() is changed when we call rep.AddThread() to add new thread into rep
Say in one iteration of for loop, we add threads[i]->parent_tid into rep, and in the next iteration of for loop, we add threads[i]->parent_tid->parent_tid into rep.
Maybe this version is confusing, I' happy to change code as you expected :)

[Enna1]

compiler-rt/lib/tsan/rtl/tsan_rtl_report.cpp

830

Sorry, I misunderstand, I will update patch.

[dvyukov]

compiler-rt/lib/tsan/rtl/tsan_rtl_report.cpp

830

You are right. The code is fine as is, no need to change.

[Enna1]

Thanks for your review. I don't have commit accesss, Can you commit this for me? Thanks!

compiler-rt/lib/tsan/rtl/tsan_flags.inc

 TSAN_FLAG(const char *, suppressions, "", "Suppressions file name.")
 TSAN_FLAG(bool, ignore_interceptors_accesses, SANITIZER_MAC ? true : false,
           "Ignore reads and writes from all interceptors.")
 TSAN_FLAG(bool, ignore_noninstrumented_modules, SANITIZER_MAC ? true : false,
           "Interceptors should only detect races when called from instrumented "
           "modules.")
 TSAN_FLAG(bool, shared_ptr_interceptor, true,
           "Track atomic reference counting in libc++ shared_ptr and weak_ptr.")
+TSAN_FLAG(bool, print_full_thread_history, false,
+          "If set, prints thread creation stacks for the threads involved in "
+          "the report and their ancestors up to the main thread.")

compiler-rt/lib/tsan/rtl/tsan_rtl_report.cpp

void ReportRace(ThreadState *thr, RawShadow *shadow_mem, Shadow cur, Shadow old,
   for (uptr i = 0; i < kMop; i++) {
     ThreadContext *tctx = static_cast<ThreadContext *>(
         ctx->thread_registry.GetThreadLocked(tids[i]));
     rep.AddThread(tctx);
   }
 
   rep.AddLocation(addr_min, addr_max - addr_min);
 
+  if (flags()->print_full_thread_history) {
+    const ReportDesc *rep_desc = rep.GetReport();
+    for (uptr i = 0; i < rep_desc->threads.Size(); i++) {
+      Tid parent_tid = rep_desc->threads[i]->parent_tid;
+      if (parent_tid == kMainTid || parent_tid == kInvalidTid)
+        continue;
+      ThreadContext *parent_tctx = static_cast<ThreadContext *>(
+          ctx->thread_registry.GetThreadLocked(parent_tid));
+      rep.AddThread(parent_tctx);
+    }
+  }
+
 #if !SANITIZER_GO
   if (!((typ0 | typ1) & kAccessFree) &&
       s[1].epoch() <= thr->last_sleep_clock.Get(s[1].sid()))
     rep.AddSleep(thr->last_sleep_stack_id);
 #endif
   OutputReport(thr, rep);
 }
 

compiler-rt/test/tsan/print_full_thread_history.cpp

+// RUN: %clangxx_tsan -O1 %s -o %t && %env_tsan_opts=print_full_thread_history=true %deflake %run %t 2>&1 | FileCheck %s
+
+#include "test.h"
+
+int Global;
+
+void *Thread2(void *x) {
+  barrier_wait(&barrier);
+  Global++;
+  return NULL;
+}
+
+void *Thread3(void *x) {
+  Global--;
+  barrier_wait(&barrier);
+  return NULL;
+}
+
+void *Thread1(void *x) {
+  pthread_t t[2];
+  pthread_create(&t[0], NULL, Thread2, NULL);
+  pthread_create(&t[1], NULL, Thread3, NULL);
+  pthread_join(t[0], NULL);
+  pthread_join(t[1], NULL);
+  return NULL;
+}
+
+int main() {
+  barrier_init(&barrier, 2);
+  pthread_t t;
+  pthread_create(&t, NULL, Thread1, NULL);
+  pthread_join(t, NULL);
+  return 0;
+}
+
+// CHECK: WARNING: ThreadSanitizer: data race
+// CHECK:        Thread T2 {{.*}} created by thread T1 at
+// CHECK:        Thread T3 {{.*}} created by thread T1 at:
+// CHECK:        Thread T1 {{.*}} created by main thread at:
+// CHECK: SUMMARY: ThreadSanitizer: data race{{.*}}