Illumos 5812 - assertion failed in zrl_tryenter(): zr_owner==NULL

5812 assertion failed in zrl_tryenter(): zr_owner==NULL
Reviewed by: George Wilson <george@delphix.com>
Reviewed by: Alex Reece <alex@delphix.com>
Reviewed by: Will Andrews <will@freebsd.org>
Approved by: Gordon Ross <gwr@nexenta.com>

References:
  https://www.illumos.org/issues/5812
  illumos/illumos-gate@8df1730

Ported-by: DHE <git@dehacked.net>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #3357

Author: ahrens

module/zfs/zrlock.c

@@ -20,6 +20,7 @@
  */
 /*
  * Copyright (c) 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2014 by Delphix. All rights reserved.
  */
 
 /*
@@ -43,7 +44,7 @@
  * A ZRL can be locked only while there are zero references, so ZRL_LOCKED is
  * treated as zero references.
  */
-#define	ZRL_LOCKED	((uint32_t)-1)
+#define	ZRL_LOCKED	-1
 #define	ZRL_DESTROYED	-2
 
 void
@@ -61,7 +62,7 @@ zrl_init(zrlock_t *zrl)
 void
 zrl_destroy(zrlock_t *zrl)
 {
-	ASSERT(zrl->zr_refcount == 0);
+	ASSERT0(zrl->zr_refcount);
 
 	mutex_destroy(&zrl->zr_mtx);
 	zrl->zr_refcount = ZRL_DESTROYED;
@@ -81,7 +82,7 @@ zrl_add(zrlock_t *zrl)
 		uint32_t cas = atomic_cas_32(
 		    (uint32_t *)&zrl->zr_refcount, n, n + 1);
 		if (cas == n) {
-			ASSERT((int32_t)n >= 0);
+			ASSERT3S((int32_t)n, >=, 0);
 #ifdef	ZFS_DEBUG
 			if (zrl->zr_owner == curthread) {
 				DTRACE_PROBE2(zrlock__reentry,
@@ -99,7 +100,7 @@ zrl_add(zrlock_t *zrl)
 	while (zrl->zr_refcount == ZRL_LOCKED) {
 		cv_wait(&zrl->zr_cv, &zrl->zr_mtx);
 	}
-	ASSERT(zrl->zr_refcount >= 0);
+	ASSERT3S(zrl->zr_refcount, >=, 0);
 	zrl->zr_refcount++;
 #ifdef	ZFS_DEBUG
 	zrl->zr_owner = curthread;
@@ -113,14 +114,14 @@ zrl_remove(zrlock_t *zrl)
 {
 	uint32_t n;
 
-	n = atomic_dec_32_nv((uint32_t *)&zrl->zr_refcount);
-	ASSERT((int32_t)n >= 0);
 #ifdef	ZFS_DEBUG
 	if (zrl->zr_owner == curthread) {
 		zrl->zr_owner = NULL;
 		zrl->zr_caller = NULL;
 	}
 #endif
+	n = atomic_dec_32_nv((uint32_t *)&zrl->zr_refcount);
+	ASSERT3S((int32_t)n, >=, 0);
 }
 
 int
@@ -133,26 +134,26 @@ zrl_tryenter(zrlock_t *zrl)
 		    (uint32_t *)&zrl->zr_refcount, 0, ZRL_LOCKED);
 		if (cas == 0) {
 #ifdef	ZFS_DEBUG
-			ASSERT(zrl->zr_owner == NULL);
+			ASSERT3P(zrl->zr_owner, ==, NULL);
 			zrl->zr_owner = curthread;
 #endif
 			return (1);
 		}
 	}
 
-	ASSERT((int32_t)n > ZRL_DESTROYED);
+	ASSERT3S((int32_t)n, >, ZRL_DESTROYED);
 
 	return (0);
 }
 
 void
 zrl_exit(zrlock_t *zrl)
 {
-	ASSERT(zrl->zr_refcount == ZRL_LOCKED);
+	ASSERT3S(zrl->zr_refcount, ==, ZRL_LOCKED);
 
 	mutex_enter(&zrl->zr_mtx);
 #ifdef	ZFS_DEBUG
-	ASSERT(zrl->zr_owner == curthread);
+	ASSERT3P(zrl->zr_owner, ==, curthread);
 	zrl->zr_owner = NULL;
 	membar_producer();	/* make sure the owner store happens first */
 #endif
@@ -166,7 +167,7 @@ zrl_refcount(zrlock_t *zrl)
 {
 	int n;
 
-	ASSERT(zrl->zr_refcount > ZRL_DESTROYED);
+	ASSERT3S(zrl->zr_refcount, >, ZRL_DESTROYED);
 
 	n = (int)zrl->zr_refcount;
 	return (n <= 0 ? 0 : n);
@@ -175,15 +176,15 @@ zrl_refcount(zrlock_t *zrl)
 int
 zrl_is_zero(zrlock_t *zrl)
 {
-	ASSERT(zrl->zr_refcount > ZRL_DESTROYED);
+	ASSERT3S(zrl->zr_refcount, >, ZRL_DESTROYED);
 
 	return (zrl->zr_refcount <= 0);
 }
 
 int
 zrl_is_locked(zrlock_t *zrl)
 {
-	ASSERT(zrl->zr_refcount > ZRL_DESTROYED);
+	ASSERT3S(zrl->zr_refcount, >, ZRL_DESTROYED);
 
 	return (zrl->zr_refcount == ZRL_LOCKED);
 }