From ca86d51602c829fd799f1dbef51c99b34e003447 Mon Sep 17 00:00:00 2001
From: Attilio Rao <attilio@FreeBSD.org>
Date: Mon, 20 Oct 2008 19:22:16 +0000
Subject: [PATCH] In the actual code for witness_warn: - If there aren't
 spinlocks held, but there are problems with old   sleeplocks, they are not
 reported. - If the spinlock found is not the only one, problems are not
 reported.

Fix these 2 problems.

Reported by:	tegge
---
 sys/kern/subr_witness.c | 29 +++++++++++------------------
 1 file changed, 11 insertions(+), 18 deletions(-)

diff --git a/sys/kern/subr_witness.c b/sys/kern/subr_witness.c
index ee36ae0ecb5..48c4b5c35b6 100644
--- a/sys/kern/subr_witness.c
+++ b/sys/kern/subr_witness.c
@@ -1628,13 +1628,7 @@ witness_warn(int flags, struct lock_object *lock, const char *fmt, ...)
 	 */
 	sched_pin();
 	lock_list = PCPU_GET(spinlocks);
-	if (lock_list != NULL) {
-
-		/* Empty list? */
-		if (lock_list->ll_count == 0) {
-			sched_unpin();
-			return (n);
-		}
+	if (lock_list != NULL && lock_list->ll_count != 0) {
 		sched_unpin();
 
 		/*
@@ -1644,18 +1638,17 @@ witness_warn(int flags, struct lock_object *lock, const char *fmt, ...)
 		 * should hold.
 		 */
 		lock1 = &lock_list->ll_children[lock_list->ll_count - 1];
-		if (lock1->li_lock == lock)
-			return (n);
+		if (lock_list->ll_count == 1 && lock_list->ll_next == NULL &&
+		    lock1->li_lock == lock && n == 0)
+			return (0);
 
-		if (n == 0) {
-			va_start(ap, fmt);
-			vprintf(fmt, ap);
-			va_end(ap);
-			printf(" with the following");
-			if (flags & WARN_SLEEPOK)
-				printf(" non-sleepable");
-			printf(" locks held:\n");
-		}
+		va_start(ap, fmt);
+		vprintf(fmt, ap);
+		va_end(ap);
+		printf(" with the following");
+		if (flags & WARN_SLEEPOK)
+			printf(" non-sleepable");
+		printf(" locks held:\n");
 		n += witness_list_locks(&lock_list);
 	} else
 		sched_unpin();