66298e1c54
The false positive fixed by commitf831d6fc80("tsan: fix false positive during fd close") still happens episodically on the added more stressful test which does just open/close. I don't have a coherent explanation as to what exactly happens but the fix fixes the false positive on this test as well. The issue may be related to lost writes during asynchronous MADV_DONTNEED. I've debugged similar unexplainable false positive related to freed and reused memory and at the time the only possible explanation I found is that an asynchronous MADV_DONTNEED may lead to lost writes. That's why commit302ec7b9bc("tsan: add memory_limit_mb flag") added StopTheWorld around the memory flush, but unfortunately the commit does not capture these findings. Reviewed By: melver Differential Revision: https://reviews.llvm.org/D121363
29 lines
729 B
C++
29 lines
729 B
C++
// RUN: %clangxx_tsan -O1 %s -o %t && %env_tsan_opts=flush_memory_ms=1 %run %t 2>&1 | FileCheck %s
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#include "test.h"
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#include <fcntl.h>
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#include <sys/stat.h>
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#include <sys/types.h>
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#include <unistd.h>
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void *Thread(void *stop) {
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while (!__atomic_load_n((int *)stop, __ATOMIC_RELAXED))
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close(open("/dev/null", O_RDONLY));
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return 0;
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}
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int main() {
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int stop = 0;
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const int kThreads = 10;
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pthread_t th[kThreads];
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for (int i = 0; i < kThreads; i++)
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pthread_create(&th[i], 0, Thread, &stop);
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sleep(5);
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__atomic_store_n(&stop, 1, __ATOMIC_RELAXED);
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for (int i = 0; i < kThreads; i++)
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pthread_join(th[i], 0);
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fprintf(stderr, "DONE\n");
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}
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// CHECK-NOT: WARNING: ThreadSanitizer: data race
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// CHECK: DONE
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