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From "William A. Rowe, Jr." <wr...@rowe-clan.net>
Subject [PATCH] Thread Locks and SMP boxes
Date Wed, 30 Jul 2003 16:21:21 GMT
Attached is a patch that appears to be as close as thread-safe
(but altogether not reentrant) as I can accomplish.

The existing unix/thread_mutex.c code is neither thread-safe
nor reentrant when using the 'nested' (default) thread mutexes.
The bug is most often expressed on SMP boxes, where they
are so massively parallel that the subtle flaws of modifying the
mutex object AFTER we have released the lock become very

Examples include a number of error (45) Deadlock Avoided
alerts using Apache2/mod_ssl on Solaris, where there are both
internal thread locks and global locks which contain a nested
thread lock.

Many more eyes on this code would be welcomed, I expect to
discover that we repeat this mistake elsewhere in the mutex

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