Implement zero system call thread switching. Performance of

thread switches should be on par with that under scheduler
activations.

  o Timing is achieved through the use of a fixed interval
    timer (ITIMER_PROF) to count scheduling ticks instead
    of retrieving the time-of-day upon every thread switch
    and calculating elapsed real time.

  o Polling for I/O readiness is performed once for each
    scheduling tick instead of every thread switch.

  o The non-signal saving/restoring versions of setjmp/longjmp
    are used to save and restore thread contexts.  This may
    allow the removal of _THREAD_SAFE macros from setjmp()
    and longjmp() - needs more investigation.

Change signal handling so that signals are handled in the
context of the thread that is receiving the signal.  When
signals are dispatched to a thread, a special signal handling
frame is created on top of the target threads stack.  The
frame contains the threads saved state information and a new
context in which the thread can run.  The applications signal
handler is invoked through a wrapper routine that knows how
to restore the threads saved state and unwind to previous
frames.

Fix interruption of threads due to signals.  Some states
were being improperly interrupted while other states were
not being interrupted.  This should fix several PRs.

Signal handlers, which are invoked as a result of a process
signal (not by pthread_kill()), are now called with the
code (or siginfo_t if SA_SIGINFO was set in sa_flags) and
sigcontext_t as received from the process signal handler.

Modify the search for a thread to which a signal is delivered.
The search algorithm is now:

  o First thread found in sigwait() with signal in wait mask.
  o First thread found sigsuspend()'d on the signal.
  o Current thread if signal is unmasked.
  o First thread found with signal unmasked.

Collapse machine dependent support into macros defined in
pthread_private.h.  These should probably eventually be moved
into separate MD files.

Change the range of settable priorities to be compliant with
POSIX (0-31).  The threads library uses higher priorities
internally for real-time threads (not yet implemented) and
threads executing signal handlers.  Real-time threads and
threads running signal handlers add 64 and 32, respectively,
to a threads base priority.

Some other small changes and cleanups.

PR:		17757 18559 21943
Reviewed by:	jasone

1 files changed, 48 insertions, 16 deletions

diff --git a/lib/libkse/thread/thr_mutex.c b/lib/libkse/thread/thr_mutex.c
index b8877f8..f7662c7 100644
--- a/lib/libkse/thread/thr_mutex.c
+++ b/lib/libkse/thread/thr_mutex.c
@@ -79,7 +79,7 @@ static spinlock_t static_init_lock = _SPINLOCK_INITIALIZER;
 int
 _mutex_reinit(pthread_mutex_t * mutex)
 {
-	int ret = 0;
+	int	ret = 0;
 
 	if (mutex == NULL)
 		ret = EINVAL;
@@ -113,7 +113,7 @@ pthread_mutex_init(pthread_mutex_t * mutex,
 	int		protocol;
 	int		ceiling;
 	pthread_mutex_t	pmutex;
-	int             ret = 0;
+	int		ret = 0;
 
 	if (mutex == NULL)
 		ret = EINVAL;
@@ -203,7 +203,7 @@ pthread_mutex_init(pthread_mutex_t * mutex,
 int
 pthread_mutex_destroy(pthread_mutex_t * mutex)
 {
-	int ret = 0;
+	int	ret = 0;
 
 	if (mutex == NULL || *mutex == NULL)
 		ret = EINVAL;
@@ -245,7 +245,7 @@ pthread_mutex_destroy(pthread_mutex_t * mutex)
 static int
 init_static(pthread_mutex_t *mutex)
 {
-	int ret;
+	int	ret;
 
 	_SPINLOCK(&static_init_lock);
 
@@ -262,7 +262,7 @@ init_static(pthread_mutex_t *mutex)
 int
 pthread_mutex_trylock(pthread_mutex_t * mutex)
 {
-	int             ret = 0;
+	int	ret = 0;
 
 	if (mutex == NULL)
 		ret = EINVAL;
@@ -400,7 +400,7 @@ pthread_mutex_trylock(pthread_mutex_t * mutex)
 int
 pthread_mutex_lock(pthread_mutex_t * mutex)
 {
-	int             ret = 0;
+	int	ret = 0;
 
 	if (mutex == NULL)
 		ret = EINVAL;
@@ -610,9 +610,8 @@ pthread_mutex_lock(pthread_mutex_t * mutex)
 		 * Check to see if this thread was interrupted and
 		 * is still in the mutex queue of waiting threads:
 		 */
-		if (_thread_run->interrupted != 0) {
+		if (_thread_run->interrupted != 0)
 			mutex_queue_remove(*mutex, _thread_run);
-		}
 
 		/* Unlock the mutex structure: */
 		_SPINUNLOCK(&(*mutex)->lock);
@@ -647,7 +646,7 @@ _mutex_cv_unlock(pthread_mutex_t * mutex)
 int
 _mutex_cv_lock(pthread_mutex_t * mutex)
 {
-	int ret;
+	int	ret;
 	if ((ret = pthread_mutex_lock(mutex)) == 0)
 		(*mutex)->m_refcount--;
 	return (ret);
@@ -656,7 +655,7 @@ _mutex_cv_lock(pthread_mutex_t * mutex)
 static inline int
 mutex_self_trylock(pthread_mutex_t mutex)
 {
-	int ret = 0;
+	int	ret = 0;
 
 	switch (mutex->m_type) {
 
@@ -723,7 +722,7 @@ mutex_self_lock(pthread_mutex_t mutex)
 static inline int
 mutex_unlock_common(pthread_mutex_t * mutex, int add_reference)
 {
-	int ret = 0;
+	int	ret = 0;
 
 	if (mutex == NULL || *mutex == NULL) {
 		ret = EINVAL;
@@ -1369,6 +1368,38 @@ _mutex_unlock_private(pthread_t pthread)
 	}
 }
 
+void
+_mutex_lock_backout(pthread_t pthread)
+{
+	struct pthread_mutex	*mutex;
+
+	/*
+	 * Defer signals to protect the scheduling queues from
+	 * access by the signal handler:
+	 */
+	_thread_kern_sig_defer();
+	if (pthread->state == PS_MUTEX_WAIT) {
+		mutex = pthread->data.mutex;
+
+		/* Lock the mutex structure: */
+		_SPINLOCK(&mutex->lock);
+
+		mutex_queue_remove(mutex, pthread);
+
+		/* This thread is no longer waiting for the mutex: */
+		mutex->m_owner->data.mutex = NULL;
+
+		/* Unlock the mutex structure: */
+		_SPINUNLOCK(&mutex->lock);
+
+	}
+	/*
+	 * Undefer and handle pending signals, yielding if
+	 * necessary:
+	 */
+	_thread_kern_sig_undefer();
+}
+
 /*
  * Dequeue a waiting thread from the head of a mutex queue in descending
  * priority order.
@@ -1379,7 +1410,7 @@ mutex_queue_deq(pthread_mutex_t mutex)
 	pthread_t pthread;
 
 	while ((pthread = TAILQ_FIRST(&mutex->m_queue)) != NULL) {
-		TAILQ_REMOVE(&mutex->m_queue, pthread, qe);
+		TAILQ_REMOVE(&mutex->m_queue, pthread, sqe);
 		pthread->flags &= ~PTHREAD_FLAGS_IN_MUTEXQ;
 
 		/*
@@ -1400,7 +1431,7 @@ static inline void
 mutex_queue_remove(pthread_mutex_t mutex, pthread_t pthread)
 {
 	if ((pthread->flags & PTHREAD_FLAGS_IN_MUTEXQ) != 0) {
-		TAILQ_REMOVE(&mutex->m_queue, pthread, qe);
+		TAILQ_REMOVE(&mutex->m_queue, pthread, sqe);
 		pthread->flags &= ~PTHREAD_FLAGS_IN_MUTEXQ;
 	}
 }
@@ -1413,18 +1444,19 @@ mutex_queue_enq(pthread_mutex_t mutex, pthread_t pthread)
 {
 	pthread_t tid = TAILQ_LAST(&mutex->m_queue, mutex_head);
 
+	PTHREAD_ASSERT_NOT_IN_SYNCQ(pthread);
 	/*
 	 * For the common case of all threads having equal priority,
 	 * we perform a quick check against the priority of the thread
 	 * at the tail of the queue.
 	 */
 	if ((tid == NULL) || (pthread->active_priority <= tid->active_priority))
-		TAILQ_INSERT_TAIL(&mutex->m_queue, pthread, qe);
+		TAILQ_INSERT_TAIL(&mutex->m_queue, pthread, sqe);
 	else {
 		tid = TAILQ_FIRST(&mutex->m_queue);
 		while (pthread->active_priority <= tid->active_priority)
-			tid = TAILQ_NEXT(tid, qe);
-		TAILQ_INSERT_BEFORE(tid, pthread, qe);
+			tid = TAILQ_NEXT(tid, sqe);
+		TAILQ_INSERT_BEFORE(tid, pthread, sqe);
 	}
 	pthread->flags |= PTHREAD_FLAGS_IN_MUTEXQ;
 }