Fix the wrapper function around signals so that a signal handling

thread on one of the mutex or condition variable queues is removed
from those queues before the real signal handler is called.

5 files changed, 57 insertions, 58 deletions

diff --git a/lib/libthr/thread/thr_cond.c b/lib/libthr/thread/thr_cond.c
index 00dbb25..367a54e 100644
--- a/lib/libthr/thread/thr_cond.c
+++ b/lib/libthr/thread/thr_cond.c
@@ -419,24 +419,15 @@ _cond_wait_backout(pthread_t pthread)
 	if (cond == NULL)
 		return;
 
-	COND_LOCK(cond);
-
 	/* Process according to condition variable type: */
 	switch (cond->c_type) {
 	/* Fast condition variable: */
 	case COND_TYPE_FAST:
-		_thread_critical_enter(curthread);
-
 		cond_queue_remove(cond, pthread);
-
-		_thread_critical_exit(curthread);
 		break;
-
 	default:
 		break;
 	}
-
-	COND_UNLOCK(cond);
 }
 
 /*
diff --git a/lib/libthr/thread/thr_mutex.c b/lib/libthr/thread/thr_mutex.c
index 722772b..ec0ffc9 100644
--- a/lib/libthr/thread/thr_mutex.c
+++ b/lib/libthr/thread/thr_mutex.c
@@ -1284,20 +1284,7 @@ _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();*/
-
-	/* XXX - Necessary to obey lock order */
-	UMTX_LOCK(&pthread->lock);
 	mutex = pthread->data.mutex;
-	UMTX_UNLOCK(&pthread->lock);
-
-	_SPINLOCK(&mutex->lock);
-
-	_thread_critical_enter(pthread);
 	if ((pthread->flags & PTHREAD_FLAGS_IN_MUTEXQ) != 0) {
 
 		mutex_queue_remove(mutex, pthread);
@@ -1306,14 +1293,6 @@ _mutex_lock_backout(pthread_t pthread)
 		pthread->data.mutex = NULL;
 
 	}
-	/*
-	 * Undefer and handle pending signals, yielding if
-	 * necessary:
-	 */
-	/* _thread_kern_sig_undefer(); */
-
-	_thread_critical_exit(pthread);
-	_SPINUNLOCK(&mutex->lock);
 }
 
 /*
@@ -1426,14 +1405,13 @@ get_mcontested(pthread_mutex_t mutexp)
 {
 	int error;
 
-	_thread_critical_enter(curthread);
-
 	/*
 	 * Put this thread on the mutex's list of waiting threads.
 	 * The lock on the thread ensures atomic (as far as other
 	 * threads are concerned) setting of the thread state with
 	 * it's status on the mutex queue.
 	 */
+	_thread_critical_enter(curthread);
 	mutex_queue_enq(mutexp, curthread);
 	do {
 		PTHREAD_SET_STATE(curthread, PS_MUTEX_WAIT);
@@ -1443,10 +1421,8 @@ get_mcontested(pthread_mutex_t mutexp)
 		error = _thread_suspend(curthread, NULL);
 		if (error != 0 && error != EAGAIN && error != EINTR)
 			PANIC("Cannot suspend on mutex.");
-
 		_SPINLOCK(&mutexp->lock);
 		_thread_critical_enter(curthread);
 	} while ((curthread->flags & PTHREAD_FLAGS_IN_MUTEXQ) != 0);
-
 	_thread_critical_exit(curthread);
 }
diff --git a/lib/libthr/thread/thr_private.h b/lib/libthr/thread/thr_private.h
index 41078a5..67ef7e0 100644
--- a/lib/libthr/thread/thr_private.h
+++ b/lib/libthr/thread/thr_private.h
@@ -782,6 +782,7 @@ int	_pthread_mutexattr_settype(pthread_mutexattr_t *, int);
 int	_pthread_once(pthread_once_t *, void (*) (void));
 pthread_t _pthread_self(void);
 int	_pthread_setspecific(pthread_key_t, const void *);
+int	_spintrylock(spinlock_t *);
 void    _thread_exit(char *, int, char *);
 void    _thread_exit_cleanup(void);
 void    *_thread_cleanup(pthread_t);
diff --git a/lib/libthr/thread/thr_sig.c b/lib/libthr/thread/thr_sig.c
index a9f7f83..48b3388 100644
--- a/lib/libthr/thread/thr_sig.c
+++ b/lib/libthr/thread/thr_sig.c
@@ -36,6 +36,8 @@
 #include <setjmp.h>
 #include <errno.h>
 #include <pthread.h>
+#include <stdlib.h>
+
 #include "thr_private.h"
 
 /* #define DEBUG_SIGNAL */
@@ -116,13 +118,10 @@ void
 _thread_sig_wrapper(int sig, siginfo_t *info, void *context)
 {
 	struct pthread_state_data psd;
+	struct sigaction *actp;
 	__siginfohandler_t *handler;
-
-	GIANT_LOCK(curthread);
-	/* Save the thread's previous state. */
-	psd.psd_wait_data = curthread->data;
-	psd.psd_state = curthread->state;
-	psd.psd_flags = curthread->flags;
+	struct umtx *up;
+	spinlock_t *sp;
 
 	/*
 	 * Do a little cleanup handling for those threads in
@@ -130,33 +129,54 @@ _thread_sig_wrapper(int sig, siginfo_t *info, void *context)
 	 * for these threads are temporarily blocked until
 	 * after cleanup handling.
 	 */
-	switch (psd.psd_state) {
+	switch (curthread->state) {
 	case PS_COND_WAIT:
+		/*
+		 * Cache the address, since it will not be available
+		 * after it has been backed out.
+		 */
+		up = &curthread->data.cond->c_lock;
+
+		UMTX_LOCK(up);
+		_thread_critical_enter(curthread);
 		_cond_wait_backout(curthread);
-		psd.psd_state = PS_RUNNING;
+		UMTX_UNLOCK(up);
 		break;
-
 	case PS_MUTEX_WAIT:
+		/*
+		 * Cache the address, since it will not be available
+		 * after it has been backed out.
+		 */
+		sp = &curthread->data.mutex->lock;
+
+		_SPINLOCK(sp);
+		_thread_critical_enter(curthread);
 		_mutex_lock_backout(curthread);
-		psd.psd_state = PS_RUNNING;
+		_SPINUNLOCK(sp);
 		break;
-
 	default:
+		/*
+		 * We need to lock the thread to read it's flags.
+		 */
+		_thread_critical_enter(curthread);
 		break;
 	}
 
-	if (_thread_sigact[sig -1].sa_handler != NULL) {
-		GIANT_UNLOCK(curthread);
-		handler = (__siginfohandler_t *)
-			_thread_sigact[sig - 1].sa_handler;
-		handler(sig, info, (ucontext_t *)context);
-		GIANT_LOCK(curthread);
-	}
+	/*
+	 * We save the flags now so that any modifications done as part
+	 * of the backout are reflected when the flags are restored.
+	 */
+	psd.psd_flags = curthread->flags;
 
-        /* Restore the signal frame. */
-	curthread->data = psd.psd_wait_data;
-	curthread->state = psd.psd_state;
-	curthread->flags = psd.psd_flags &
-	    (PTHREAD_FLAGS_PRIVATE | PTHREAD_FLAGS_TRACE);
-	GIANT_UNLOCK(curthread);
+	PTHREAD_SET_STATE(curthread, PS_RUNNING);
+	_thread_critical_exit(curthread);
+	actp = proc_sigact_sigaction(sig);
+	handler = (__siginfohandler_t *)actp->sa_handler;
+	handler(sig, info, (ucontext_t *)context);
+
+        /* Restore the thread's flags, and make it runnable */
+	_thread_critical_enter(curthread);
+	curthread->flags = psd.psd_flags;
+	PTHREAD_NEW_STATE(curthread, PS_RUNNING);
+	_thread_critical_exit(curthread);
 }
diff --git a/lib/libthr/thread/thr_spinlock.c b/lib/libthr/thread/thr_spinlock.c
index 259977a..322d2e7 100644
--- a/lib/libthr/thread/thr_spinlock.c
+++ b/lib/libthr/thread/thr_spinlock.c
@@ -64,6 +64,17 @@ _spinlock(spinlock_t *lck)
 		abort();
 }
 
+int
+_spintrylock(spinlock_t *lck)
+{
+	int error;
+
+	error = umtx_lock((struct umtx *)lck, curthread->thr_id);
+	if (error != 0 && error != EBUSY)
+		abort();
+	return (error);
+}
+
 /*
  * Lock a location for the running thread. Yield to allow other
  * threads to run if this thread is blocked because the lock is