History log of /bionic/libc/bionic/pthread_join.cpp
Revision Date Author Comments
877ec6d90418ff1d6597147d355a2229fdffae7e 16-Nov-2013 Elliott Hughes <enh@google.com> Fix pthread_join.

Let the kernel keep pthread_internal_t::tid updated, including
across forks and for the main thread. This then lets us fix
pthread_join to only return after the thread has really exited.

Also fix the thread attributes of the main thread so we don't
unmap the main thread's stack (which is really owned by the
dynamic linker and contains things like environment variables),
which fixes crashes when joining with an exited main thread
and also fixes problems reported publicly with accessing environment
variables after the main thread exits (for which I've added a new
unit test).

In passing I also fixed a bug where if the clone(2) inside
pthread_create(3) fails, we'd unmap the child's stack and TLS (which
contains the mutex) and then try to unlock the mutex. Boom! It wasn't
until after I'd uploaded the fix for this that I came across a new
public bug reporting this exact failure.

Bug: 8206355
Bug: 11693195
Bug: https://code.google.com/p/android/issues/detail?id=57421
Bug: https://code.google.com/p/android/issues/detail?id=62392
Change-Id: I2af9cf6e8ae510a67256ad93cad891794ed0580b
0f020d18b138e24b1fe34074808e07ac412f35a4 06-Jun-2013 msg555 <msg555@gmail.com> 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
9d23e04c43dbb8480bea8be28b8a2f37423bec49 16-Feb-2013 Elliott Hughes <enh@google.com> Fix pthreads functions that should return ESRCH.

imgtec pointed out that pthread_kill(3) was broken, but most of the
other functions that ought to return ESRCH for invalid/exited threads
were equally broken.

Change-Id: I96347f6195549aee0c72dc39063e6c5d06d2e01f