Mike Makonnen 4cd18a22d5 Make libthr async-signal-safe without costly signal masking. The guidlines I ... 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.		2004-05-20 12:06:16 +00:00
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arch	Make NULL a (void*)0 whereever possible, and fix the warnings(-Werror)	2004-03-05 08:10:19 +00:00
sys	- Adjust the makefiles so we have a per architecture makefile.	2003-04-01 07:07:38 +00:00
thread	Make libthr async-signal-safe without costly signal masking. The guidlines I	2004-05-20 12:06:16 +00:00
Makefile	Relink libc_r.a, libc_r.so and libc_r_p.so from libthr to libkse.	2003-09-27 23:27:19 +00:00