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* Make libthr async-signal-safe without costly signal masking. The guidlines Imtm2004-05-201-157/+65
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | followed are: Only 3 functions (pthread_cancel, pthread_setcancelstate, pthread_setcanceltype) are required to be async-signal-safe by POSIX. None of the rest of the pthread api is required to be async-signal-safe. This means that only the three mentioned functions are safe to use from inside signal handlers. However, there are certain system/libc calls that are cancellation points that a caller may call from within a signal handler, and since they are cancellation points calls have to be made into libthr to test for cancellation and exit the thread if necessary. So, the cancellation test and thread exit code paths must be async-signal-safe as well. A summary of the changes follows: o Almost all of the code paths that masked signals, as well as locking the pthread structure now lock only the pthread structure. o Signals are masked (and left that way) as soon as a thread enters pthread_exit(). o The active and dead threads locks now explicitly require that signals are masked. o Access to the isdead field of the pthread structure is protected by both the active and dead list locks for writing. Either one is sufficient for reading. o The thread state and type fields have been combined into one three-state switch to make it easier to read without requiring a lock. It doesn't need a lock for writing (and therefore for reading either) because only the current thread can write to it and it is an integer value. o The thread state field of the pthread structure has been eliminated. It was an unnecessary field that mostly duplicated the flags field, but required additional locking that would make a lot more code paths require signal masking. Any truly unique values (such as PS_DEAD) have been reborn as separate members of the pthread structure. o Since the mutex and condvar pthread functions are not async-signal-safe there is no need to muck about with the wait queues when handling a signal ... o ... which also removes the need for wrapping signal handlers and sigaction(2). o The condvar and mutex async-cancellation code had to be revised as a result of some of these changes, which resulted in semi-unrelated changes which would have been difficult to work on as a separate commit, so they are included as well. The only part of the changes I am worried about is related to locking for the pthread joining fields. But, I will take a closer look at them once this mega-patch is committed.
* Implement PThreads barriers and barrier attributes.mtm2004-02-191-0/+1
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* Change all instances of THR_LOCK/UNLOCK, etc to UMTX_*.mtm2003-07-061-2/+2
| | | | | It is a more acurate description of the locks they operate on.
* There's no need for _umtxtrylock to be a separate function.mtm2003-07-061-1/+2
| | | | Roll it into the pre-existing macro that's used to call it.
* Sweep through pthread locking and use the new locking primitives formtm2003-06-291-2/+2
| | | | libthr.
* _pthread_cancel() breaks the normal lock order of first locking themtm2003-05-251-4/+17
| | | | | | | | | | | | | joined and then the joiner thread. There isn't an easy (sane?) way to make it use the correct order without introducing races involving the target thread and finding which (active or dead) list it is on. So, after locking the canceled thread it will try to lock the joined thread and if it fails release the first lock and try again from the top. Introduce a new function, _spintrylock, which is simply a wrapper arround umtx_trylock(), to help accomplish this. Approved by: re/blanket libthr
* Make WARNS2 clean. The fixes mostly included:mtm2003-05-231-0/+1
| | | | | | | | o removed unused variables o explicit inclusion of header files o prototypes for externally defined functions Approved by: re/blanket libthr
* o Make the setting/checking of cancel state atomic withmtm2003-05-151-87/+111
| | | | | | | | | | | | | | respect to other threads and signal handlers by moving to the _thread_critical_enter/exit functions. o Introduce an static function, testcancel(), that is used by the other functions in this module. This allows it to make locking assumptions that the top-level functions can't. o Rework the code flow a bit to reduce indentation levels. Approved by: markm/mentor, re/blanket libthr Reviewed by: jeff
* - Define curthread as _get_curthread() and remove all direct calls tojeff2003-04-021-10/+0
| | | | | | | _get_curthread(). This is similar to the kernel's curthread. Doing this saves stack overhead and is more convenient to the programmer. - Pass the pointer to the newly created thread to _thread_init(). - Remove _get_curthread_slow().
* - Add libthr but don't hook it up to the regular build yet. This is anjeff2003-04-011-0/+205
adaptation of libc_r for the thr system call interface. This is beta quality code.
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