ARC: stack unwinding: reorganize how initial register state setup

This is a non-functional change, if anything a better fall-back
handling.
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

arch/arc/kernel/stacktrace.c

@@ -42,11 +42,23 @@ static int
 seed_unwind_frame_info(struct task_struct *tsk, struct pt_regs *regs,
 		       struct unwind_frame_info *frame_info)
 {
-	/*
-	 * synchronous unwinding (e.g. dump_stack)
-	 *  - uses current values of SP and friends
-	 */
-	if (regs == NULL && (tsk == NULL || tsk == current)) {
+	if (regs) {
+		/*
+		 * Asynchronous unwinding of intr/exception
+		 *  - Just uses the pt_regs passed
+		 */
+		frame_info->task = tsk;
+
+		frame_info->regs.r27 = regs->fp;
+		frame_info->regs.r28 = regs->sp;
+		frame_info->regs.r31 = regs->blink;
+		frame_info->regs.r63 = regs->ret;
+		frame_info->call_frame = 0;
+	} else if (tsk == NULL || tsk == current) {
+		/*
+		 * synchronous unwinding (e.g. dump_stack)
+		 *  - uses current values of SP and friends
+		 */
 		unsigned long fp, sp, blink, ret;
 		frame_info->task = current;
 
@@ -63,7 +75,7 @@ seed_unwind_frame_info(struct task_struct *tsk, struct pt_regs *regs,
 		frame_info->regs.r31 = blink;
 		frame_info->regs.r63 = ret;
 		frame_info->call_frame = 0;
-	} else if (regs == NULL) {
+	} else {
 		/*
 		 * Asynchronous unwinding of a likely sleeping task
 		 *  - first ensure it is actually sleeping
@@ -94,20 +106,7 @@ seed_unwind_frame_info(struct task_struct *tsk, struct pt_regs *regs,
 		frame_info->regs.r28 += 60;
 		frame_info->call_frame = 0;
 
-	} else {
-		/*
-		 * Asynchronous unwinding of intr/exception
-		 *  - Just uses the pt_regs passed
-		 */
-		frame_info->task = tsk;
-
-		frame_info->regs.r27 = regs->fp;
-		frame_info->regs.r28 = regs->sp;
-		frame_info->regs.r31 = regs->blink;
-		frame_info->regs.r63 = regs->ret;
-		frame_info->call_frame = 0;
 	}
-
 	return 0;
 }