Commit Graph

14 Commits

Author SHA1 Message Date
Mike Makonnen
b9662ddd18 Teach recent changes in the umtx structure in the kernel to the libthr
initialiazer.

Found by:	tinderbox
2003-06-03 09:31:33 +00:00
Mike Makonnen
ca1c469cc7 Decouple the thread stack [de]allocating functions from the 'dead threads list'
lock. It's not really necessary and we don't need the added complexity
or potential for deadlocks.

Approved by:	re/blanket libthr
2003-05-26 00:37:07 +00:00
Mike Makonnen
12c407a424 Return gracefully, rather than aborting, when the maximum concurrent
threads per process has been reached. Return EAGAIN, as per spec.

Approved by:	re/blanket libthr
2003-05-25 22:40:57 +00:00
Mike Makonnen
d39d651258 _pthread_cancel() breaks the normal lock order of first locking the
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
2003-05-25 08:48:11 +00:00
Mike Makonnen
71d09bc86a Start locking up the active and dead threads lists. The active threads
list is protected by a spinlock_t, but the dead list uses a pthread_mutex
because it is necessary to synchronize other threads with the garbage
collector thread. Lock/Unlock macros are used so it's easier to make
changes to the locks in the future.

The 'dead thread list' lock is intended to replace the gc mutex.
This doesn't have any practical ramifications. It simply makes it
clearer what the purpose of the lock is. The gc will use this lock,
instead of the gc mutex, to synchronize access to the dead list with
other threads.

Modify _pthread_exit() to use these two new locks instead of GIANT_LOCK,
and also to properly lock and protect thread state changes,
especially with respect to a joining thread.

The gc thread was also re-arranged to be more organized and less nested.

_pthread_join() was also modified to use the thread list locks. However,
locking and unlocking here needs special care because a thread could find
itself in a position where it's joining an exiting thread that is
waiting on the dead list lock, which this thread (joiner) holds. If the
joiner doesn't take care to lock *and* unlock in the same order they
(the joiner and the joinee) could deadlock against each other.

Approved by:	re/blanket libthr
2003-05-25 08:31:33 +00:00
Mike Makonnen
6a1899ed5c The libthr code makes use of higher-level primitives (pthread_mutex_t and
pthread_cond_t) internaly in addition to the low-level spinlock_t. The
garbage collector mutex and condition variable are two such examples. This
might lead to critical sections nested within critical sections. Implement
a reference counting mechanism so that signals are masked only on the first
entry and unmasked on the last exit.

I'm not sure I like the idea of nested critical sections, but if
the library is going to use the pthread primitives it might be necessary.

Approved by:	re/blanket libthr
2003-05-25 07:58:22 +00:00
Mike Makonnen
59a47b31d0 Add two functions: _spinlock_pthread() and _spinunlock_pthread()
that take the address of a struct pthread as their first argument.
_spin[un]lock() just become wrappers arround these two functions.
These new functions are for use in situations where curthread can't be
used. One example is _thread_retire(), where we invalidate the array index
curthread uses to get its pointer..

Approved by:	re/blanket libthr
2003-05-23 23:39:31 +00:00
Mike Makonnen
b32a99e5f4 EDOOFUS
Prevent one thread from messing up another thread's saved signal
mask by saving it in struct pthread instead of leaving it as a
global variable. D'oh!

Approved by:	re/blanket libthr
2003-05-23 10:28:13 +00:00
Mike Makonnen
7d9d7ca2ed Make WARNS2 clean. The fixes mostly included:
o removed unused variables
	o explicit inclusion of header files
	o prototypes for externally defined functions

Approved by:    re/blanket libthr
2003-05-23 09:48:20 +00:00
Mike Makonnen
c984b5a72a msg1 2003-05-12 10:34:01 +00:00
Jake Burkholder
55ad402a8f - Pass a ucontext_t to _set_curthread. If non-NULL the new thread is set
as curthread in the new context, so that it will be set automatically when
  the thread is switched to.  This fixes a race where we'd run for a little
  while with curthread unset in _thread_start.

Reviewed by:	jeff
2003-04-03 03:34:50 +00:00
Jeff Roberson
26f52e2f8b - Define curthread as _get_curthread() and remove all direct calls to
_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().
2003-04-02 03:05:39 +00:00
Jeff Roberson
360a519459 - Restore old mutex code from libc_r. It is more standards compliant.
This was changed because originally we were blocking on the umtx and
   allowing the kernel to do the queueing.  It was decided that the
   lib should queue and start the threads in the order it decides and the
   umtx code would just be used like spinlocks.
2003-04-01 22:39:31 +00:00
Jeff Roberson
bb535300dd - Add libthr but don't hook it up to the regular build yet. This is an
adaptation of libc_r for the thr system call interface.  This is beta
   quality code.
2003-04-01 03:46:29 +00:00