1 files changed, 227 insertions, 72 deletions

diff --git a/lib/libc_r/uthread/uthread_sig.c b/lib/libc_r/uthread/uthread_sig.c
index e73d5a2..1e5ee63 100644
--- a/lib/libc_r/uthread/uthread_sig.c
+++ b/lib/libc_r/uthread/uthread_sig.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1995 John Birrell <jb@cimlogic.com.au>.
+ * Copyright (c) 1995-1998 John Birrell <jb@cimlogic.com.au>
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -38,16 +38,79 @@
 #include <pthread.h>
 #include "pthread_private.h"
 
+/* Static variables: */
+static int	volatile yield_on_unlock_dead		= 0;
+static int	volatile yield_on_unlock_thread	= 0;
+static long	volatile thread_dead_lock		= 0;
+static long	volatile thread_link_list_lock		= 0;
+
+/* Lock the thread list: */
+void
+_lock_thread_list()
+{
+	/* Lock the thread list: */
+	_spinlock(&thread_link_list_lock);
+}
+
+/* Lock the dead thread list: */
+void
+_lock_dead_thread_list()
+{
+	/* Lock the dead thread list: */
+	_spinlock(&thread_dead_lock);
+}
+
+/* Lock the thread list: */
+void
+_unlock_thread_list()
+{
+	/* Unlock the thread list: */
+	_atomic_unlock(&thread_link_list_lock);
+
+	/*
+	 * Check if a scheduler interrupt occurred while the thread
+	 * list was locked:
+	 */
+	if (yield_on_unlock_thread) {
+		/* Reset the interrupt flag: */
+		yield_on_unlock_thread = 0;
+
+		/* This thread has overstayed it's welcome: */
+		sched_yield();
+	}
+}
+
+/* Lock the dead thread list: */
+void
+_unlock_dead_thread_list()
+{
+	/* Unlock the dead thread list: */
+	_atomic_unlock(&thread_dead_lock);
+
+	/*
+	 * Check if a scheduler interrupt occurred while the dead
+	 * thread list was locked:
+	 */
+	if (yield_on_unlock_dead) {
+		/* Reset the interrupt flag: */
+		yield_on_unlock_dead = 0;
+
+		/* This thread has overstayed it's welcome: */
+		sched_yield();
+	}
+}
+
 void
 _thread_sig_handler(int sig, int code, struct sigcontext * scp)
 {
 	char            c;
 	int             i;
+	int		dispatch = 0;
 	pthread_t       pthread;
 
 	/*
 	 * Check if the pthread kernel has unblocked signals (or is about to)
-	 * and was on its way into a _thread_sys_select when the current
+	 * and was on its way into a _select when the current
 	 * signal interrupted it: 
 	 */
 	if (_thread_kern_in_select) {
@@ -57,51 +120,65 @@ _thread_sig_handler(int sig, int code, struct sigcontext * scp)
 		/*
 		 * Write the signal number to the kernel pipe so that it will
 		 * be ready to read when this signal handler returns. This
-		 * means that the _thread_sys_select call will complete
+		 * means that the _select call will complete
 		 * immediately. 
 		 */
-		if (_thread_sys_write(_thread_kern_pipe[1], &c, 1) != 1) {
-		}
+		_thread_sys_write(_thread_kern_pipe[1], &c, 1);
 	}
+
 	/* Check if the signal requires a dump of thread information: */
-	if (sig == SIGINFO) {
+	if (sig == SIGINFO)
 		/* Dump thread information to file: */
 		_thread_dump_info();
-	} else {
-		/* Handle depending on signal type: */
-		switch (sig) {
-		/* Interval timer used for timeslicing: */
-		case SIGVTALRM:
+
+	/* Check if an interval timer signal: */
+	else if (sig == SIGVTALRM) {
+		/* Check if the scheduler interrupt has come at an
+		 * unfortunate time which one of the threads is
+		 * modifying the thread list:
+		 */
+		if (thread_link_list_lock)
 			/*
-			 * Don't add the signal to any thread.  Just want to
-			 * call the scheduler:
+			 * Set a flag so that the thread that has
+			 * the lock yields when it unlocks the
+			 * thread list:
 			 */
-			break;
+			yield_on_unlock_thread = 1;
 
-		/* Child termination: */
-		case SIGCHLD:
+		/* Check if the scheduler interrupt has come at an
+		 * unfortunate time which one of the threads is
+		 * modifying the dead thread list:
+		 */
+		if (thread_dead_lock)
 			/*
-			 * Enter a loop to process each thread in the linked
-			 * list:
+			 * Set a flag so that the thread that has
+			 * the lock yields when it unlocks the
+			 * dead thread list:
 			 */
-			for (pthread = _thread_link_list; pthread != NULL;
-			     pthread = pthread->nxt) {
-				/*
-				 * Add the signal to the set of pending
-				 * signals:
-				 */
-				pthread->sigpend[sig] += 1;
-				if (pthread->state == PS_WAIT_WAIT) {
-					/* Reset the error: */
-					/* There should be another flag so that this is not required! ### */
-					_thread_seterrno(pthread, 0);
-
-					/* Change the state of the thread to run: */
-					PTHREAD_NEW_STATE(pthread,PS_RUNNING);
-				}
-			}
+			yield_on_unlock_dead = 1;
+
+		/*
+		 * Check if the kernel has not been interrupted while
+		 * executing scheduler code:
+		 */
+		else if (!_thread_kern_in_sched) {
+			/*
+			 * Schedule the next thread. This function is not
+			 * expected to return because it will do a longjmp
+			 * instead. 
+			 */
+			_thread_kern_sched(scp);
 
 			/*
+			 * This point should not be reached, so abort the
+			 * process: 
+			 */
+			PANIC("Returned to signal function from scheduler");
+		}
+	} else {
+		/* Check if a child has terminated: */
+		if (sig == SIGCHLD) {
+			/*
 			 * Go through the file list and set all files
 			 * to non-blocking again in case the child
 			 * set some of them to block. Sigh.
@@ -109,59 +186,137 @@ _thread_sig_handler(int sig, int code, struct sigcontext * scp)
 			for (i = 0; i < _thread_dtablesize; i++) {
 				/* Check if this file is used: */
 				if (_thread_fd_table[i] != NULL) {
-					/* Set the file descriptor to non-blocking: */
-					_thread_sys_fcntl(i, F_SETFL, _thread_fd_table[i]->flags | O_NONBLOCK);
+					/*
+					 * Set the file descriptor to
+					 * non-blocking:
+					 */
+					_thread_sys_fcntl(i, F_SETFL,
+					    _thread_fd_table[i]->flags |
+					    O_NONBLOCK);
 				}
 			}
-			break;
+		}
 
-		/* Signals specific to the running thread: */
-		case SIGBUS:
-		case SIGEMT:
-		case SIGFPE:
-		case SIGILL:
-		case SIGPIPE:
-		case SIGSEGV:
-		case SIGSYS:
-			/* Add the signal to the set of pending signals: */
-			_thread_run->sigpend[sig] += 1;
-			break;
+		/*
+		 * POSIX says that pending SIGCONT signals are
+		 * discarded when one of there signals occurs.
+		 */
+		if (sig == SIGTSTP || sig == SIGTTIN || sig == SIGTTOU) {
+			/*
+			 * Enter a loop to discard pending SIGCONT
+			 * signals:
+			 */
+			for (pthread = _thread_link_list;
+			    pthread != NULL;
+			    pthread = pthread->nxt)
+				sigdelset(&pthread->sigpend,SIGCONT);
+		}
 
-		/* Signals to send to all threads: */
-		default:
+		/* Check if the signal is not being ignored: */
+		if (_thread_sigact[sig - 1].sa_handler != SIG_IGN)
 			/*
 			 * Enter a loop to process each thread in the linked
 			 * list: 
 			 */
 			for (pthread = _thread_link_list; pthread != NULL;
-			     pthread = pthread->nxt) {
-				/*
-				 * Add the signal to the set of pending
-				 * signals: 
-				 */
-				pthread->sigpend[sig] += 1;
-			}
+			     pthread = pthread->nxt)
+				_thread_signal(pthread,sig);
+
+		/* Dispatch pending signals to the running thread: */
+		_dispatch_signals();
+	}
+
+	/* Returns nothing. */
+	return;
+}
+
+/* Perform thread specific actions in response to a signal: */
+void
+_thread_signal(pthread_t pthread, int sig)
+{
+	pthread_t saved;
+	struct sigaction act;
+
+	/*
+	 * Flag the signal as pending. It will be dispatched later.
+	 */
+	sigaddset(&pthread->sigpend,sig);
+
+	/* Check if system calls are not restarted: */
+	if ((_thread_sigact[sig - 1].sa_flags & SA_RESTART) == 0) {
+		/*
+		 * Process according to thread state:
+		 */
+		switch (pthread->state) {
+		/*
+		 * States which do not change when a signal is trapped:
+		 */
+		case PS_COND_WAIT:
+		case PS_DEAD:
+		case PS_FDLR_WAIT:
+		case PS_FDLW_WAIT:
+		case PS_FILE_WAIT:
+		case PS_JOIN:
+		case PS_MUTEX_WAIT:
+		case PS_RUNNING:
+		case PS_STATE_MAX:
+		case PS_SIGTHREAD:
+		case PS_SUSPENDED:
+			/* Nothing to do here. */
+			break;
+
+		/*
+		 * States that are interrupted by the occurrence of a signal
+		 * other than the scheduling alarm: 
+		 */
+		case PS_FDR_WAIT:
+		case PS_FDW_WAIT:
+		case PS_SLEEP_WAIT:
+		case PS_SIGWAIT:
+		case PS_WAIT_WAIT:
+		case PS_SELECT_WAIT:
+			/* Flag the operation as interrupted: */
+			pthread->interrupted = 1;
+
+			/* Change the state of the thread to run: */
+			PTHREAD_NEW_STATE(pthread,PS_RUNNING);
+
+			/* Return the signal number: */
+			pthread->signo = sig;
 			break;
 		}
+	}
+}
 
-		/* Check if the kernel is not locked: */
-		if (_thread_run != &_thread_kern_thread) {
-			/*
-			 * Schedule the next thread. This function is not
-			 * expected to return because it will do a longjmp
-			 * instead. 
-			 */
-			_thread_kern_sched(scp);
+/* Dispatch pending signals to the running thread: */
+void
+_dispatch_signals()
+{
+	int i;
 
+	/*
+	 * Check if there are pending signals for the running
+	 * thread that aren't blocked:
+	 */
+	if ((_thread_run->sigpend & ~_thread_run->sigmask) != 0)
+		/* Look for all possible pending signals: */
+		for (i = 1; i < NSIG; i++)
 			/*
-			 * This point should not be reached, so abort the
-			 * process: 
+			 * Check that a custom handler is installed
+			 * and if the signal is not blocked:
 			 */
-			PANIC("Returned to signal function from scheduler");
-		}
-	}
+			if (_thread_sigact[i - 1].sa_handler != SIG_DFL &&
+			    _thread_sigact[i - 1].sa_handler != SIG_IGN &&
+			    sigismember(&_thread_run->sigpend,i) &&
+			    !sigismember(&_thread_run->sigmask,i)) {
+				/* Clear the pending signal: */
+				sigdelset(&_thread_run->sigpend,i);
 
-	/* Returns nothing. */
-	return;
+				/*
+				 * Dispatch the signal via the custom signal
+				 * handler:
+				 */
+				(*(_thread_sigact[i - 1].sa_handler))(i);
+			}
 }
 #endif