ia64: Rearrange ia64_do_signal() such that it is possible for a debugger to

	cancel system-call restart.

arch/ia64/kernel/signal.c

@@ -538,6 +538,19 @@ ia64_do_signal (sigset_t *oldset, struct sigscratch *scr, long in_syscall)
 	if (!oldset)
 		oldset = &current->blocked;
 
+	/*
+	 * This only loops in the rare cases of handle_signal() failing, in which case we
+	 * need to push through a forced SIGSEGV.
+	 */
+	while (1) {
+		int signr = get_signal_to_deliver(&info, &scr->pt, NULL);
+
+		/*
+		 * get_signal_to_deliver() may have run a debugger (via notify_parent())
+		 * and the debugger may have modified the state (e.g., to arrange for an
+		 * inferior call), thus it's important to check for restarting _after_
+		 * get_signal_to_deliver().
+		 */
 		if (IS_IA32_PROCESS(&scr->pt)) {
 			if (in_syscall) {
 				if (errno >= 0)
@@ -554,15 +567,12 @@ ia64_do_signal (sigset_t *oldset, struct sigscratch *scr, long in_syscall)
 			 */
 			restart = 0;
 
-	while (1) {
-		int signr = get_signal_to_deliver(&info, &scr->pt, NULL);
-
 		if (signr <= 0)
 			break;
 
 		ka = &current->sighand->action[signr - 1];
 
-		if (restart) {
+		if (unlikely(restart)) {
 			switch (errno) {
 			      case ERESTART_RESTARTBLOCK:
 			      case ERESTARTNOHAND:
@@ -582,6 +592,7 @@ ia64_do_signal (sigset_t *oldset, struct sigscratch *scr, long in_syscall)
 					scr->pt.cr_iip -= 2;
 				} else
 					ia64_decrement_ip(&scr->pt);
+				restart = 0; /* don't restart twice if handle_signal() fails... */
 			}
 		}