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author | Peter Maydell <peter.maydell@linaro.org> | 2018-11-05 13:55:38 +0000 |
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committer | Paolo Bonzini <pbonzini@redhat.com> | 2018-11-06 21:35:06 +0100 |
commit | a458774ad711bceabefbf01e8f0b91d86ec72e0c (patch) | |
tree | 1bffb5098e9418dc2688d2c137b3f82189486a5f /hw/misc | |
parent | ca95173c7fb64a1544b1f560766976425659e5e4 (diff) | |
download | qemu-a458774ad711bceabefbf01e8f0b91d86ec72e0c.zip qemu-a458774ad711bceabefbf01e8f0b91d86ec72e0c.tar.gz qemu-a458774ad711bceabefbf01e8f0b91d86ec72e0c.tar.bz2 |
util/qemu-thread-posix: Fix qemu_thread_atexit* for OSX
Our current implementation of qemu_thread_atexit* is broken on OSX.
This is because it works by cerating a piece of thread-specific
data with pthread_key_create() and using the destructor function
for that data to run the notifier function passed to it by
the caller of qemu_thread_atexit_add(). The expected use case
is that the caller uses a __thread variable as the notifier,
and uses the callback to clean up information that it is
keeping per-thread in __thread variables.
Unfortunately, on OSX this does not work, because on OSX
a __thread variable may be destroyed (freed) before the
pthread_key_create() destructor runs. (POSIX imposes no
ordering constraint here; the OSX implementation happens
to implement __thread variables in terms of pthread_key_create((),
whereas Linux uses different mechanisms that mean the __thread
variables will still be present when the pthread_key_create()
destructor is run.)
Fix this by switching to a scheme similar to the one qemu-thread-win32
uses for qemu_thread_atexit: keep the thread's notifiers on a
__thread variable, and run the notifiers on calls to
qemu_thread_exit() and on return from the start routine passed
to qemu_thread_start(). We do this with the pthread_cleanup_push()
API.
We take advantage of the qemu_thread_atexit_add() API
permission not to run thread notifiers on process exit to
avoid having to special case the main thread.
Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20181105135538.28025-3-peter.maydell@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'hw/misc')
0 files changed, 0 insertions, 0 deletions