[PATCH] D52330: SafeStack: Fix flaky test (PR39001)

[Vlad Tsyrklevich via Phabricator via llvm-commits]

vlad.tsyrklevich created this revision.
vlad.tsyrklevich added reviewers: jmorse, eugenis, vitalybuka.
Herald added subscribers: Sanitizers, llvm-commits, jfb, delcypher.

pthread_join() can return before a thread finishes exit()ing in the
kernel and a subsequent tgkill() can report the thread still alive.
Update the pthread-cleanup.c test to sleep and retry if it hits this
possible flake.

Thanks to Jeremy Morse for reporting.


Repository:
  rCRT Compiler Runtime

https://reviews.llvm.org/D52330

Files:
  test/safestack/pthread-cleanup.c


Index: test/safestack/pthread-cleanup.c
===================================================================
--- test/safestack/pthread-cleanup.c
+++ test/safestack/pthread-cleanup.c
@@ -29,18 +29,26 @@
   if (pthread_join(t1, &t1_buffer))
     abort();
 
+  // Stack has not yet been deallocated
   memset(t1_buffer, 0, kBufferSize);
 
   if (arg == 0)
     return 0;
 
-  if (pthread_create(&t2, NULL, start, NULL))
-    abort();
-  // Second thread destructor cleans up the first thread's stack.
-  if (pthread_join(t2, NULL))
-    abort();
-
-  // should segfault here
-  memset(t1_buffer, 0, kBufferSize);
+  for (int i = 0; i < 3; i++) {
+    if (pthread_create(&t2, NULL, start, NULL))
+      abort();
+    // Second thread destructor cleans up the first thread's stack.
+    if (pthread_join(t2, NULL))
+      abort();
+
+    // Should segfault here
+    memset(t1_buffer, 0, kBufferSize);
+
+    // PR39001: Re-try in the rare case that pthread_join() returns before the
+    // thread finishes exiting in the kernel--hence the tgkill() check for t1
+    // returns that it's alive despite pthread_join() returning.
+    sleep(1);
+  }
   return 0;
 }


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D52330.166379.patch
Type: text/x-patch
Size: 1160 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20180920/3f092006/attachment.bin>