Handles spurious wake-ups in pthread_join()
Removed 'join_count' from pthread_internal_t and switched to using the flag PTHREAD_ATTR_FLAG_JOINED to indicate if a thread is being joined. Combined with a switch to a while loop in pthread_join, this fixes spurious wake-ups but prevents a thread from being joined multiple times. This is fine for two reasons: 1) The pthread_join specification allows for undefined behavior when multiple threads try to join a single thread. 2) There is no thread safe way to allow multiple threads to join a single thread with the pthread interface. The second thread calling pthread_join could be pre-empted until the thread is destroyed and its handle reused for a different thread. Therefore multi-join is always an error. Bug: https://code.google.com/p/android/issues/detail?id=52255 Change-Id: I8b6784d47620ffdcdbfb14524e7402e21d46c5f7
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@@ -40,7 +40,7 @@ int pthread_detach(pthread_t t) {
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return EINVAL; // Already detached.
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}
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if (thread->join_count > 0) {
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if (thread->attr.flags & PTHREAD_ATTR_FLAG_JOINED) {
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return 0; // Already being joined; silently do nothing, like glibc.
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}
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