diff -ru mysql-5.0.54_orig/innobase/configure mysql-5.0.54/innobase/configure
--- mysql-5.0.54_orig/innobase/configure	2007-12-25 00:20:37.000000000 +0900
+++ mysql-5.0.54/innobase/configure	2008-01-26 12:41:00.000000000 +0900
@@ -21058,6 +21058,88 @@
 fi
 done
 
+
+# as http://lists.mysql.com/commits/40686 does
+{ echo "$as_me:$LINENO: checking whether the compiler provides atomic builtins" >&5
+echo $ECHO_N "checking whether the compiler provides atomic builtins... $ECHO_C" >&6; }
+if test "${mysql_cv_atomic_builtins+set}" = set; then
+  echo $ECHO_N "(cached) $ECHO_C" >&6
+else
+  if test "$cross_compiling" = yes; then
+  { { echo "$as_me:$LINENO: error: cannot run test program while cross compiling
+See \`config.log' for more details." >&5
+echo "$as_me: error: cannot run test program while cross compiling
+See \`config.log' for more details." >&2;}
+   { (exit 1); exit 1; }; }
+else
+  cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+
+  int main()
+  {
+    int foo= -10; int bar= 10;
+    __sync_fetch_and_add(&foo, bar);
+    if (foo)
+      return -1;
+    bar= __sync_lock_test_and_set(&foo, bar);
+    if (bar || foo != 10)
+      return -1;
+    bar= __sync_val_compare_and_swap(&bar, foo, 15);
+    if (bar)
+      return -1;
+    return 0;
+  }
+
+_ACEOF
+rm -f conftest$ac_exeext
+if { (ac_try="$ac_link"
+case "(($ac_try" in
+  *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
+  *) ac_try_echo=$ac_try;;
+esac
+eval "echo \"\$as_me:$LINENO: $ac_try_echo\"") >&5
+  (eval "$ac_link") 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); } && { ac_try='./conftest$ac_exeext'
+  { (case "(($ac_try" in
+  *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
+  *) ac_try_echo=$ac_try;;
+esac
+eval "echo \"\$as_me:$LINENO: $ac_try_echo\"") >&5
+  (eval "$ac_try") 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; }; then
+  mysql_cv_atomic_builtins=yes
+else
+  echo "$as_me: program exited with status $ac_status" >&5
+echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+( exit $ac_status )
+mysql_cv_atomic_builtins=no
+fi
+rm -f core *.core core.conftest.* gmon.out bb.out conftest$ac_exeext conftest.$ac_objext conftest.$ac_ext
+fi
+
+
+fi
+{ echo "$as_me:$LINENO: result: $mysql_cv_atomic_builtins" >&5
+echo "${ECHO_T}$mysql_cv_atomic_builtins" >&6; }
+
+if test "x$mysql_cv_atomic_builtins" = xyes; then
+
+cat >>confdefs.h <<\_ACEOF
+#define HAVE_ATOMIC_BUILTINS 1
+_ACEOF
+
+fi
+
 #AC_CHECK_FUNCS(readdir_r) MySQL checks that it has also the right args.
 # Some versions of Unix only take 2 arguments.
 #AC_C_INLINE  Already checked in MySQL
diff -ru mysql-5.0.54_orig/innobase/configure.in mysql-5.0.54/innobase/configure.in
--- mysql-5.0.54_orig/innobase/configure.in	2007-04-19 10:36:16.000000000 +0900
+++ mysql-5.0.54/innobase/configure.in	2008-01-26 12:41:00.000000000 +0900
@@ -42,6 +42,31 @@
 AC_CHECK_FUNCS(sched_yield)
 AC_CHECK_FUNCS(fdatasync)
 AC_CHECK_FUNCS(localtime_r)
+
+# as http://lists.mysql.com/commits/40686 does
+AC_CACHE_CHECK([whether the compiler provides atomic builtins],
+               [mysql_cv_atomic_builtins], [AC_TRY_RUN([
+  int main()
+  {
+    int foo= -10; int bar= 10;
+    __sync_fetch_and_add(&foo, bar);
+    if (foo)
+      return -1;
+    bar= __sync_lock_test_and_set(&foo, bar);
+    if (bar || foo != 10)
+      return -1;
+    bar= __sync_val_compare_and_swap(&bar, foo, 15);
+    if (bar)
+      return -1;
+    return 0;
+  }
+], [mysql_cv_atomic_builtins=yes], [mysql_cv_atomic_builtins=no])])
+
+if test "x$mysql_cv_atomic_builtins" = xyes; then
+  AC_DEFINE(HAVE_ATOMIC_BUILTINS, 1,
+            [Define to 1 if compiler provides atomic builtins.])
+fi
+
 #AC_CHECK_FUNCS(readdir_r) MySQL checks that it has also the right args.
 # Some versions of Unix only take 2 arguments.
 #AC_C_INLINE  Already checked in MySQL
diff -ru mysql-5.0.54_orig/innobase/ib_config.h mysql-5.0.54/innobase/ib_config.h
--- mysql-5.0.54_orig/innobase/ib_config.h	2007-12-25 00:22:15.000000000 +0900
+++ mysql-5.0.54/innobase/ib_config.h	2008-01-26 12:41:00.000000000 +0900
@@ -4,6 +4,9 @@
 /* Define to 1 if you have the <aio.h> header file. */
 #define HAVE_AIO_H 1
 
+/* Define to 1 if compiler provides atomic builtins. */
+#define HAVE_ATOMIC_BUILTINS 1
+
 /* Define to 1 if you have the <dlfcn.h> header file. */
 #define HAVE_DLFCN_H 1
 
diff -ru mysql-5.0.54_orig/innobase/ib_config.h.in mysql-5.0.54/innobase/ib_config.h.in
--- mysql-5.0.54_orig/innobase/ib_config.h.in	2007-12-25 00:20:28.000000000 +0900
+++ mysql-5.0.54/innobase/ib_config.h.in	2008-01-26 12:41:00.000000000 +0900
@@ -3,6 +3,9 @@
 /* Define to 1 if you have the <aio.h> header file. */
 #undef HAVE_AIO_H
 
+/* Define to 1 if compiler provides atomic builtins. */
+#undef HAVE_ATOMIC_BUILTINS
+
 /* Define to 1 if you have the <dlfcn.h> header file. */
 #undef HAVE_DLFCN_H
 
diff -ru mysql-5.0.54_orig/innobase/include/sync0rw.h mysql-5.0.54/innobase/include/sync0rw.h
--- mysql-5.0.54_orig/innobase/include/sync0rw.h	2007-11-21 02:38:06.000000000 +0900
+++ mysql-5.0.54/innobase/include/sync0rw.h	2008-01-26 13:35:20.000000000 +0900
@@ -323,11 +323,24 @@
 	rw_lock_t*	lock);	/* in: rw-lock */
 /************************************************************************
 Accessor functions for rw lock. */
+#ifdef HAVE_ATOMIC_BUILTINS
+UNIV_INLINE
+ulint
+rw_lock_get_s_waiters(
+/*==================*/
+	rw_lock_t*	lock);
+UNIV_INLINE
+ulint
+rw_lock_get_x_waiters(
+/*==================*/
+	rw_lock_t*	lock);
+#else
 UNIV_INLINE
 ulint
 rw_lock_get_waiters(
 /*================*/
 	rw_lock_t*	lock);
+#endif
 UNIV_INLINE
 ulint
 rw_lock_get_writer(
@@ -408,6 +421,11 @@
 	rw_lock_debug_t*	info);	/* in: debug struct */
 #endif /* UNIV_SYNC_DEBUG */
 
+#ifdef HAVE_ATOMIC_BUILTINS
+/* This value means NOT_LOCKED */
+#define RW_LOCK_BIAS		0x00100000
+#endif
+
 /* NOTE! The structure appears here only for the compiler to know its size.
 Do not use its fields directly! The structure used in the spin lock
 implementation of a read-write lock. Several threads may have a shared lock
@@ -417,7 +435,12 @@
 field. Then no new readers are allowed in. */
 
 struct rw_lock_struct {
+#ifdef HAVE_ATOMIC_BUILTINS
+	os_event_t	s_event;	/* Used by s_lock */
+	os_event_t	x_event;	/* Used by x_lock */
+#else
 	os_event_t	event;	/* Used by sync0arr.c for thread queueing */
+#endif
 
 #ifdef __WIN__
 	os_event_t	wait_ex_event;	/* This windows specific event is
@@ -429,29 +452,40 @@
 				signalled. See LEMMA 2 in sync0sync.c */
 #endif
 
-	ulint	reader_count;	/* Number of readers who have locked this
+#ifdef HAVE_ATOMIC_BUILTINS
+	volatile lint	lock_word;	/* Used by using atomic builtin */
+#endif
+
+	volatile ulint	reader_count;	/* Number of readers who have locked this
 				lock in the shared mode */
-	ulint	writer; 	/* This field is set to RW_LOCK_EX if there
+	volatile ulint	writer; 	/* This field is set to RW_LOCK_EX if there
 				is a writer owning the lock (in exclusive
 				mode), RW_LOCK_WAIT_EX if a writer is
 				queueing for the lock, and
 				RW_LOCK_NOT_LOCKED, otherwise. */
-	os_thread_id_t	writer_thread;
+	volatile os_thread_id_t	writer_thread;
 				/* Thread id of a possible writer thread */
-	ulint	writer_count;	/* Number of times the same thread has
+	volatile ulint	writer_count;	/* Number of times the same thread has
 				recursively locked the lock in the exclusive
 				mode */
+#ifndef HAVE_ATOMIC_BUILTINS
 	mutex_t	mutex;		/* The mutex protecting rw_lock_struct */
+#endif
 	ulint	pass; 		/* Default value 0. This is set to some
 				value != 0 given by the caller of an x-lock
 				operation, if the x-lock is to be passed to
 				another thread to unlock (which happens in
 				asynchronous i/o). */
-	ulint	waiters;	/* This ulint is set to 1 if there are
+#ifdef HAVE_ATOMIC_BUILTINS
+	volatile ulint	s_waiters; /* 1: there are waiters (readers) */
+	volatile ulint	x_waiters; /* 1: there are waiters (writers) */
+#else
+	volatile ulint	waiters;	/* This ulint is set to 1 if there are
 				waiters (readers or writers) in the global
 				wait array, waiting for this rw_lock.
 				Otherwise, == 0. */
-	ibool	writer_is_wait_ex;
+#endif
+	volatile ibool	writer_is_wait_ex;
 				/* This is TRUE if the writer field is
 				RW_LOCK_WAIT_EX; this field is located far
 				from the memory update hotspot fields which
diff -ru mysql-5.0.54_orig/innobase/include/sync0rw.ic mysql-5.0.54/innobase/include/sync0rw.ic
--- mysql-5.0.54_orig/innobase/include/sync0rw.ic	2007-11-21 02:38:06.000000000 +0900
+++ mysql-5.0.54/innobase/include/sync0rw.ic	2008-01-26 20:14:43.000000000 +0900
@@ -45,6 +45,40 @@
 
 /************************************************************************
 Accessor functions for rw lock. */
+#ifdef HAVE_ATOMIC_BUILTINS
+UNIV_INLINE
+ulint
+rw_lock_get_s_waiters(
+/*================*/
+	rw_lock_t*	lock)
+{
+	return(lock->s_waiters);
+}
+UNIV_INLINE
+ulint
+rw_lock_get_x_waiters(
+/*================*/
+	rw_lock_t*	lock)
+{
+	return(lock->x_waiters);
+}
+UNIV_INLINE
+void
+rw_lock_set_s_waiters(
+	rw_lock_t*	lock,
+	ulint		flag)
+{
+	lock->s_waiters = flag;
+}
+UNIV_INLINE
+void
+rw_lock_set_x_waiters(
+	rw_lock_t*	lock,
+	ulint		flag)
+{
+	lock->x_waiters = flag;
+}
+#else
 UNIV_INLINE
 ulint
 rw_lock_get_waiters(
@@ -62,13 +96,24 @@
 {
 	lock->waiters = flag;
 }
+#endif
 UNIV_INLINE
 ulint
 rw_lock_get_writer(
 /*===============*/
 	rw_lock_t*	lock)
 {
+#ifdef HAVE_ATOMIC_BUILTINS
+	/* lock->writer is used for contention of x_lock. */
+	/* We shouldn't pick up inconsistent value. */
+	ulint ret;
+	do {
+		ret = lock->writer;
+	} while(ret > RW_LOCK_WAIT_EX || ret < RW_LOCK_NOT_LOCKED);
+	return(ret);
+#else
 	return(lock->writer);
+#endif
 }
 UNIV_INLINE
 void
@@ -96,6 +141,7 @@
 {
 	lock->reader_count = count;
 }
+#ifndef HAVE_ATOMIC_BUILTINS
 UNIV_INLINE
 mutex_t*
 rw_lock_get_mutex(
@@ -104,6 +150,7 @@
 {
 	return(&(lock->mutex));
 }
+#endif
 
 /**********************************************************************
 Returns the value of writer_count for the lock. Does not reserve the lock
@@ -133,14 +180,26 @@
 	const char*	file_name, /* in: file name where lock requested */
 	ulint		line)	/* in: line where requested */
 {
-#ifdef UNIV_SYNC_DEBUG
+#if defined(UNIV_SYNC_DEBUG) && !defined(HAVE_ATOMIC_BUILTINS)
 	ut_ad(mutex_own(rw_lock_get_mutex(lock)));
 #endif /* UNIV_SYNC_DEBUG */
 	/* Check if the writer field is free */
 
+#ifdef HAVE_ATOMIC_BUILTINS
+	if (UNIV_LIKELY(rw_lock_get_writer(lock) == RW_LOCK_NOT_LOCKED)) {
+		/* try s-lock */
+		if(__sync_sub_and_fetch(&(lock->lock_word),1) <= 0) {
+			/* fail */
+			__sync_fetch_and_add(&(lock->lock_word),1);
+			return(FALSE);	/* locking did not succeed */
+		}
+		/* success */
+		__sync_fetch_and_add(&(lock->reader_count),1);
+#else
 	if (UNIV_LIKELY(lock->writer == RW_LOCK_NOT_LOCKED)) {
 		/* Set the shared lock by incrementing the reader count */
 		lock->reader_count++;
+#endif
 
 #ifdef UNIV_SYNC_DEBUG
 		rw_lock_add_debug_info(lock, pass, RW_LOCK_SHARED, file_name,
@@ -167,11 +226,15 @@
 	const char*	file_name,	/* in: file name where requested */
 	ulint		line)		/* in: line where lock requested */
 {
-	ut_ad(lock->writer == RW_LOCK_NOT_LOCKED);
+	ut_ad(rw_lock_get_writer(lock) == RW_LOCK_NOT_LOCKED);
 	ut_ad(rw_lock_get_reader_count(lock) == 0);
 	
 	/* Set the shared lock by incrementing the reader count */
+#ifdef HAVE_ATOMIC_BUILTINS
+	__sync_fetch_and_add(&(lock->reader_count),1);
+#else
 	lock->reader_count++;
+#endif
 
 	lock->last_s_file_name = file_name;
 	lock->last_s_line = line;
@@ -199,7 +262,11 @@
 
 	rw_lock_set_writer(lock, RW_LOCK_EX);
 	lock->writer_thread = os_thread_get_curr_id();
+#ifdef HAVE_ATOMIC_BUILTINS
+	__sync_fetch_and_add(&(lock->writer_count),1);
+#else
 	lock->writer_count++;
+#endif
 	lock->pass = 0;
 			
 	lock->last_x_file_name = file_name;
@@ -241,15 +308,21 @@
 	ut_ad(!rw_lock_own(lock, RW_LOCK_SHARED)); /* see NOTE above */
 #endif /* UNIV_SYNC_DEBUG */
 
+#ifndef HAVE_ATOMIC_BUILTINS
 	mutex_enter(rw_lock_get_mutex(lock));
+#endif
 
 	if (UNIV_LIKELY(rw_lock_s_lock_low(lock, pass, file_name, line))) {
+#ifndef HAVE_ATOMIC_BUILTINS
 		mutex_exit(rw_lock_get_mutex(lock));
+#endif
 
 		return; /* Success */
 	} else {
 		/* Did not succeed, try spin wait */
+#ifndef HAVE_ATOMIC_BUILTINS
 		mutex_exit(rw_lock_get_mutex(lock));
+#endif
 
 		rw_lock_s_lock_spin(lock, pass, file_name, line);
 
@@ -272,11 +345,23 @@
 {
 	ibool	success	= FALSE;
 
+#ifdef HAVE_ATOMIC_BUILTINS
+	if (rw_lock_get_writer(lock) == RW_LOCK_NOT_LOCKED) {
+		/* try s-lock */
+		if(__sync_sub_and_fetch(&(lock->lock_word),1) <= 0) {
+			/* fail */
+			__sync_fetch_and_add(&(lock->lock_word),1);
+			return(FALSE);	/* locking did not succeed */
+		}
+		/* success */
+		__sync_fetch_and_add(&(lock->reader_count),1);
+#else
 	mutex_enter(rw_lock_get_mutex(lock));
 
 	if (lock->writer == RW_LOCK_NOT_LOCKED) {
 		/* Set the shared lock by incrementing the reader count */
 		lock->reader_count++;
+#endif
 
 #ifdef UNIV_SYNC_DEBUG
 		rw_lock_add_debug_info(lock, 0, RW_LOCK_SHARED, file_name,
@@ -289,7 +374,9 @@
 		success = TRUE;
 	}
 
+#ifndef HAVE_ATOMIC_BUILTINS
 	mutex_exit(rw_lock_get_mutex(lock));
+#endif
 
 	return(success);
 }
@@ -309,6 +396,59 @@
 {
 	ibool		success		= FALSE;
 	os_thread_id_t	curr_thread	= os_thread_get_curr_id();
+#ifdef HAVE_ATOMIC_BUILTINS
+	if ((lock->lock_word == RW_LOCK_BIAS)
+			&& rw_lock_get_writer(lock) == RW_LOCK_NOT_LOCKED) {
+		/* try x-lock */
+		if(__sync_sub_and_fetch(&(lock->lock_word),
+				RW_LOCK_BIAS) == 0) {
+			/* success */
+			/* try to lock writer */
+			if(__sync_sub_and_fetch(&(lock->writer),
+					RW_LOCK_NOT_LOCKED) == 0) {
+				/* success */
+				lock->writer_thread = curr_thread;
+				lock->pass = 0;
+				/* 0 -> RW_LOCK_EX */
+				__sync_fetch_and_add(&(lock->writer),
+					RW_LOCK_EX);
+			relock:
+				__sync_fetch_and_add(&(lock->writer_count),1);
+
+#ifdef UNIV_SYNC_DEBUG
+				rw_lock_add_debug_info(lock, 0, RW_LOCK_EX, file_name, line);
+#endif
+
+				lock->last_x_file_name = file_name;
+				lock->last_x_line = line;
+
+				ut_ad(rw_lock_validate(lock));
+
+				return(TRUE);
+			} else {
+				/* fail (lock writer) */
+				__sync_fetch_and_add(&(lock->writer),
+					RW_LOCK_NOT_LOCKED);
+				/* x-unlock */
+				__sync_fetch_and_add(&(lock->lock_word),
+					RW_LOCK_BIAS);
+			}
+		} else {
+			/* fail (x-lock) */
+			__sync_fetch_and_add(&(lock->lock_word),RW_LOCK_BIAS);
+		}
+	}
+
+	if (lock->pass == 0
+			&& os_thread_eq(lock->writer_thread, curr_thread)
+			&& rw_lock_get_writer(lock) == RW_LOCK_EX) {
+		goto relock;
+	}
+
+	ut_ad(rw_lock_validate(lock));
+
+	return(FALSE);
+#else
 	mutex_enter(rw_lock_get_mutex(lock));
 
 	if (UNIV_UNLIKELY(rw_lock_get_reader_count(lock) != 0)) {
@@ -339,6 +479,7 @@
         ut_ad(rw_lock_validate(lock));
 
 	return(success);
+#endif
 }
 
 /**********************************************************************
@@ -354,16 +495,32 @@
 #endif
 	)
 {
+#ifndef HAVE_ATOMIC_BUILTINS
 	mutex_t*	mutex	= &(lock->mutex);
+#endif
 	ibool		sg 	= FALSE;
+#ifdef HAVE_ATOMIC_BUILTINS
+	ibool		last	= FALSE;
+#endif
 
+#ifndef HAVE_ATOMIC_BUILTINS
         /* Acquire the mutex protecting the rw-lock fields */
 	mutex_enter(mutex);
+#endif
 
 	/* Reset the shared lock by decrementing the reader count */
 
 	ut_a(lock->reader_count > 0);
+#ifdef HAVE_ATOMIC_BUILTINS
+	/* unlock lock_word */
+	__sync_fetch_and_add(&(lock->lock_word),1);
+
+	if(__sync_sub_and_fetch(&(lock->reader_count),1) == 0) {
+		last = TRUE;
+	}
+#else
 	lock->reader_count--;
+#endif
 
 #ifdef UNIV_SYNC_DEBUG
 	rw_lock_remove_debug_info(lock, pass, RW_LOCK_SHARED);
@@ -372,20 +529,34 @@
 	/* If there may be waiters and this was the last s-lock,
 	signal the object */
 
+#ifdef HAVE_ATOMIC_BUILTINS
+	if (UNIV_UNLIKELY(last && lock->x_waiters)) {
+#else
 	if (UNIV_UNLIKELY(lock->waiters)
 			&& lock->reader_count == 0) {
+#endif
 	       	sg = TRUE;
 
+#ifdef HAVE_ATOMIC_BUILTINS
+		rw_lock_set_x_waiters(lock, 0);
+#else
 		rw_lock_set_waiters(lock, 0);
+#endif
 	}
 	
+#ifndef HAVE_ATOMIC_BUILTINS
 	mutex_exit(mutex);
+#endif
 
 	if (UNIV_UNLIKELY(sg)) {
 #ifdef __WIN__
 		os_event_set(lock->wait_ex_event);
 #endif
+#ifdef HAVE_ATOMIC_BUILTINS
+		os_event_set(lock->x_event);
+#else
 		os_event_set(lock->event);
+#endif
 		sync_array_object_signalled(sync_primary_wait_array);
 	}
 
@@ -409,13 +580,22 @@
 
 	ut_ad(lock->reader_count > 0);
 
+#ifdef HAVE_ATOMIC_BUILTINS
+	__sync_sub_and_fetch(&(lock->reader_count),1);
+#else
 	lock->reader_count--;
+#endif
 
 #ifdef UNIV_SYNC_DEBUG
 	rw_lock_remove_debug_info(lock, 0, RW_LOCK_SHARED);
 #endif
 
+#ifdef HAVE_ATOMIC_BUILTINS
+	ut_ad(!lock->s_waiters);
+	ut_ad(!lock->x_waiters);
+#else
 	ut_ad(!lock->waiters);
+#endif
         ut_ad(rw_lock_validate(lock));
 #ifdef UNIV_SYNC_PERF_STAT
 	rw_s_exit_count++;
@@ -435,36 +615,89 @@
 #endif
 	)
 {
+#ifdef HAVE_ATOMIC_BUILTINS
+	ibool	s_sg	= FALSE;
+	ibool	x_sg	= FALSE;
+	ibool	last	= FALSE;
+#else
 	ibool	sg 	= FALSE;
 
         /* Acquire the mutex protecting the rw-lock fields */
 	mutex_enter(&(lock->mutex));
+#endif
 
 	/* Reset the exclusive lock if this thread no longer has an x-mode
 	lock */
 
 	ut_ad(lock->writer_count > 0);
 
+#ifdef HAVE_ATOMIC_BUILTINS
+	if(__sync_sub_and_fetch(&(lock->writer_count),1) == 0) {
+		last = TRUE;
+	}
+
+	if (last) {
+		/* unlock lock_word */
+		__sync_fetch_and_add(&(lock->lock_word),RW_LOCK_BIAS);
+
+		/* FIXME: It is a value of bad manners for pthread.
+		          But we shouldn't keep an ID of not-owner. */
+		lock->writer_thread = -1;
+
+		/* RW_LOCK_EX -> RW_LOCK_NOT_LOCKED */
+		__sync_fetch_and_sub(&(lock->writer),
+					(RW_LOCK_EX - RW_LOCK_NOT_LOCKED));
+	}
+#else
 	lock->writer_count--;
 
 	if (lock->writer_count == 0) {
 		rw_lock_set_writer(lock, RW_LOCK_NOT_LOCKED);
 	}
+#endif
 
 #ifdef UNIV_SYNC_DEBUG
 	rw_lock_remove_debug_info(lock, pass, RW_LOCK_EX);
 #endif
 	
 	/* If there may be waiters, signal the lock */
+#ifdef HAVE_ATOMIC_BUILTINS
+	if (last) {
+		if(lock->s_waiters){
+			s_sg = TRUE;
+			rw_lock_set_s_waiters(lock, 0);
+		}
+		if(lock->x_waiters){
+			x_sg = TRUE;
+			rw_lock_set_x_waiters(lock, 0);
+		}
+	}
+#else
 	if (UNIV_UNLIKELY(lock->waiters)
 			&& lock->writer_count == 0) {
 
 	       	sg = TRUE;
 		rw_lock_set_waiters(lock, 0);
 	}
+#endif
 	
+#ifndef HAVE_ATOMIC_BUILTINS
 	mutex_exit(&(lock->mutex));
+#endif
 
+#ifdef HAVE_ATOMIC_BUILTINS
+	if (UNIV_UNLIKELY(s_sg)) {
+		os_event_set(lock->s_event);
+		sync_array_object_signalled(sync_primary_wait_array);
+	}
+	if (UNIV_UNLIKELY(x_sg)) {
+#ifdef __WIN__
+		os_event_set(lock->wait_ex_event);
+#endif
+		os_event_set(lock->x_event);
+		sync_array_object_signalled(sync_primary_wait_array);
+	}
+#else
 	if (UNIV_UNLIKELY(sg)) {
 #ifdef __WIN__
 		os_event_set(lock->wait_ex_event);
@@ -472,6 +705,7 @@
 		os_event_set(lock->event);
 		sync_array_object_signalled(sync_primary_wait_array);
 	}
+#endif
 
         ut_ad(rw_lock_validate(lock));
 
@@ -494,9 +728,13 @@
 
 	ut_ad(lock->writer_count > 0);
 
+#ifdef HAVE_ATOMIC_BUILTINS
+	if(__sync_sub_and_fetch(&(lock->writer_count),1) == 0) {
+#else
 	lock->writer_count--;
 
 	if (lock->writer_count == 0) {
+#endif
 		rw_lock_set_writer(lock, RW_LOCK_NOT_LOCKED);
 	}
 
@@ -504,7 +742,12 @@
 	rw_lock_remove_debug_info(lock, 0, RW_LOCK_EX);
 #endif
 
+#ifdef HAVE_ATOMIC_BUILTINS
+	ut_ad(!lock->s_waiters);
+	ut_ad(!lock->x_waiters);
+#else
 	ut_ad(!lock->waiters);
+#endif
         ut_ad(rw_lock_validate(lock));
 
 #ifdef UNIV_SYNC_PERF_STAT
diff -ru mysql-5.0.54_orig/innobase/sync/sync0arr.c mysql-5.0.54/innobase/sync/sync0arr.c
--- mysql-5.0.54_orig/innobase/sync/sync0arr.c	2007-11-21 02:38:06.000000000 +0900
+++ mysql-5.0.54/innobase/sync/sync0arr.c	2008-01-26 17:41:20.000000000 +0900
@@ -314,9 +314,17 @@
 		return(os_event_reset(
 		       ((rw_lock_t *) object)->wait_ex_event));
 #endif
+#ifdef HAVE_ATOMIC_BUILTINS
+	} else if (type == RW_LOCK_SHARED) {
+		return(os_event_reset(((rw_lock_t *) object)->s_event));
+	} else { /* RW_LOCK_EX */
+		return(os_event_reset(((rw_lock_t *) object)->x_event));
+	}
+#else
 	} else {
 		return(os_event_reset(((rw_lock_t *) object)->event));
 	}
+#endif
 }		
 
 /**********************************************************************
@@ -422,9 +430,17 @@
 	} else if (cell->request_type == RW_LOCK_WAIT_EX) {
 		event = ((rw_lock_t*) cell->wait_object)->wait_ex_event;
 #endif
+#ifdef HAVE_ATOMIC_BUILTINS
+	} else if (cell->request_type == RW_LOCK_SHARED) {
+		event = ((rw_lock_t*) cell->wait_object)->s_event;
+	} else {
+		event = ((rw_lock_t*) cell->wait_object)->x_event;
+	}
+#else
 	} else {	
 		event = ((rw_lock_t*) cell->wait_object)->event;
 	}
+#endif
 
        	cell->waiting = TRUE;
 
@@ -464,6 +480,7 @@
 	mutex_t*	mutex;
 	rw_lock_t*	rwlock;
 	ulint		type;
+	ulint		writer;
 
 	type = cell->request_type;
 
@@ -505,21 +522,31 @@
 			" RW-latch at %p created in file %s line %lu\n",
 			rwlock, rwlock->cfile_name,
 			(ulong) rwlock->cline);
-		if (rwlock->writer != RW_LOCK_NOT_LOCKED) {
+		writer = rw_lock_get_writer(rwlock);
+		if (writer != RW_LOCK_NOT_LOCKED) {
 			fprintf(file,
 			"a writer (thread id %lu) has reserved it in mode %s",
 				(ulong) os_thread_pf(rwlock->writer_thread),
-				rwlock->writer == RW_LOCK_EX
+				writer == RW_LOCK_EX
 				? " exclusive\n"
 				: " wait exclusive\n");
 		}
 		
 		fprintf(file,
+#ifdef HAVE_ATOMIC_BUILTINS
+			"number of readers %lu, s_waiters flag %lu, x_waiters flag %lu\n"
+#else
 			"number of readers %lu, waiters flag %lu\n"
+#endif
 			"Last time read locked in file %s line %lu\n"
 			"Last time write locked in file %s line %lu\n",
 			(ulong) rwlock->reader_count,
+#ifdef HAVE_ATOMIC_BUILTINS
+			(ulong) rwlock->s_waiters,
+			(ulong) rwlock->x_waiters,
+#else
 			(ulong) rwlock->waiters,
+#endif
 			rwlock->last_s_file_name,
 			(ulong) rwlock->last_s_line,
 			rwlock->last_x_file_name,
@@ -839,11 +866,15 @@
 /*========================*/
 	sync_array_t*	arr)	/* in: wait array */
 {
+#ifdef HAVE_ATOMIC_BUILTINS
+	__sync_fetch_and_add(&(arr->sg_count),1);
+#else
         sync_array_enter(arr);
 
 	arr->sg_count++;
 
         sync_array_exit(arr);
+#endif
 }
 
 /**************************************************************************
@@ -888,12 +919,27 @@
 					lock = cell->wait_object;
 					os_event_set(lock->wait_ex_event);
 #endif
+#ifdef HAVE_ATOMIC_BUILTINS
+				} else if (cell->request_type
+					   == RW_LOCK_SHARED) {
+					rw_lock_t*	lock;
+
+					lock = cell->wait_object;
+					os_event_set(lock->s_event);
+				} else {
+					rw_lock_t*      lock;
+
+					lock = cell->wait_object;
+					os_event_set(lock->x_event);
+				}
+#else
 				} else {
 					rw_lock_t*	lock;
 
 					lock = cell->wait_object;
 					os_event_set(lock->event);
 				}
+#endif
                         }
                 }
 
diff -ru mysql-5.0.54_orig/innobase/sync/sync0rw.c mysql-5.0.54/innobase/sync/sync0rw.c
--- mysql-5.0.54_orig/innobase/sync/sync0rw.c	2007-11-21 02:38:06.000000000 +0900
+++ mysql-5.0.54/innobase/sync/sync0rw.c	2008-01-26 21:39:02.000000000 +0900
@@ -99,6 +99,7 @@
 	object is created, then the following call initializes
 	the sync system. */
 
+#ifndef HAVE_ATOMIC_BUILTINS
 	mutex_create(rw_lock_get_mutex(lock));
 	mutex_set_level(rw_lock_get_mutex(lock), SYNC_NO_ORDER_CHECK);
 
@@ -108,8 +109,15 @@
 	lock->mutex.cmutex_name = cmutex_name;
 	lock->mutex.mutex_type = 1;
 #endif /* UNIV_DEBUG && !UNIV_HOTBACKUP */
+#endif /* !HAVE_ATOMIC_BUILTINS */
   
+#ifdef HAVE_ATOMIC_BUILTINS
+	lock->lock_word = RW_LOCK_BIAS;
+	rw_lock_set_s_waiters(lock, 0);
+	rw_lock_set_x_waiters(lock, 0);
+#else
 	rw_lock_set_waiters(lock, 0);
+#endif
 	rw_lock_set_writer(lock, RW_LOCK_NOT_LOCKED);
 	lock->writer_count = 0;
 	rw_lock_set_reader_count(lock, 0);
@@ -130,7 +138,12 @@
 	lock->last_x_file_name = "not yet reserved";
 	lock->last_s_line = 0;
 	lock->last_x_line = 0;
+#ifdef HAVE_ATOMIC_BUILTINS
+	lock->s_event = os_event_create(NULL);
+	lock->x_event = os_event_create(NULL);
+#else
 	lock->event = os_event_create(NULL);
+#endif
 
 #ifdef __WIN__
 	lock->wait_ex_event = os_event_create(NULL);
@@ -162,15 +175,27 @@
 	ut_a(rw_lock_validate(lock));
 #endif /* UNIV_DEBUG */
 	ut_a(rw_lock_get_writer(lock) == RW_LOCK_NOT_LOCKED);
+#ifdef HAVE_ATOMIC_BUILTINS
+	ut_a(rw_lock_get_s_waiters(lock) == 0);
+	ut_a(rw_lock_get_x_waiters(lock) == 0);
+#else
 	ut_a(rw_lock_get_waiters(lock) == 0);
+#endif
 	ut_a(rw_lock_get_reader_count(lock) == 0);
 	
 	lock->magic_n = 0;
 
+#ifndef HAVE_ATOMIC_BUILTINS
 	mutex_free(rw_lock_get_mutex(lock));
+#endif
 
 	mutex_enter(&rw_lock_list_mutex);
+#ifdef HAVE_ATOMIC_BUILTINS
+	os_event_free(lock->s_event);
+	os_event_free(lock->x_event);
+#else
 	os_event_free(lock->event);
+#endif
 
 #ifdef __WIN__
 	os_event_free(lock->wait_ex_event);
@@ -191,6 +216,7 @@
 /**********************************************************************
 Checks that the rw-lock has been initialized and that there are no
 simultaneous shared and exclusive locks. */
+/* If HAVE_ATOMIC_BUILTINS, we should use this function statically. */
 
 ibool
 rw_lock_validate(
@@ -199,7 +225,9 @@
 {
 	ut_a(lock);
 
+#ifndef HAVE_ATOMIC_BUILTINS
 	mutex_enter(rw_lock_get_mutex(lock));
+#endif
 
 	ut_a(lock->magic_n == RW_LOCK_MAGIC_N);
 	ut_a((rw_lock_get_reader_count(lock) == 0)
@@ -207,11 +235,20 @@
 	ut_a((rw_lock_get_writer(lock) == RW_LOCK_EX)
 	     || (rw_lock_get_writer(lock) == RW_LOCK_WAIT_EX)
 	     || (rw_lock_get_writer(lock) == RW_LOCK_NOT_LOCKED));
+#ifdef HAVE_ATOMIC_BUILTINS
+	ut_a((rw_lock_get_s_waiters(lock) == 0)
+	     || (rw_lock_get_s_waiters(lock) == 1));
+	ut_a((rw_lock_get_x_waiters(lock) == 0)
+	     || (rw_lock_get_x_waiters(lock) == 1));
+#else
 	ut_a((rw_lock_get_waiters(lock) == 0)
 	     || (rw_lock_get_waiters(lock) == 1));
+#endif
 	ut_a((lock->writer != RW_LOCK_EX) || (lock->writer_count > 0));
 	     
+#ifndef HAVE_ATOMIC_BUILTINS
 	mutex_exit(rw_lock_get_mutex(lock));
+#endif
 
 	return(TRUE);
 }
@@ -237,13 +274,14 @@
         ut_ad(rw_lock_validate(lock));
 
 lock_loop:
+        i = 0;
+spin_loop:
 	rw_s_spin_wait_count++;
 
 	/* Spin waiting for the writer field to become free */
-        i = 0;
 
-        while (rw_lock_get_writer(lock) != RW_LOCK_NOT_LOCKED
-						&& i < SYNC_SPIN_ROUNDS) {
+        while (i < SYNC_SPIN_ROUNDS
+			&& rw_lock_get_writer(lock) != RW_LOCK_NOT_LOCKED) {
         	if (srv_spin_wait_delay) {
         		ut_delay(ut_rnd_interval(0, srv_spin_wait_delay));
         	}
@@ -262,15 +300,27 @@
 		lock->cfile_name, (ulong) lock->cline, (ulong) i);
 	}
 
+#ifndef HAVE_ATOMIC_BUILTINS
 	mutex_enter(rw_lock_get_mutex(lock));
+#endif
 
         /* We try once again to obtain the lock */
 
 	if (TRUE == rw_lock_s_lock_low(lock, pass, file_name, line)) {
+#ifndef HAVE_ATOMIC_BUILTINS
 		mutex_exit(rw_lock_get_mutex(lock));
+#endif
 
 		return; /* Success */
 	} else {
+#ifdef HAVE_ATOMIC_BUILTINS
+		/* like sync0sync.c doing */
+		i++;
+
+		if (i < SYNC_SPIN_ROUNDS) {
+			goto spin_loop;
+		}
+#endif
 		/* If we get here, locking did not succeed, we may
 		suspend the thread to wait in the wait array */
 
@@ -281,9 +331,21 @@
 				file_name, line,
 				&index);
 
+#ifdef HAVE_ATOMIC_BUILTINS
+		rw_lock_set_s_waiters(lock, 1);
+
+		/* like sync0sync.c doing */
+		for (i = 0; i < 4; i++) {
+			if (TRUE == rw_lock_s_lock_low(lock, pass, file_name, line)) {
+				sync_array_free_cell(sync_primary_wait_array, index);
+				return; /* Success */
+			}
+		}
+#else
 		rw_lock_set_waiters(lock, 1);
 
 		mutex_exit(rw_lock_get_mutex(lock));
+#endif
 
 		if (srv_print_latch_waits) {
 			fprintf(stderr,
@@ -318,13 +380,17 @@
 {
 	ut_ad(rw_lock_is_locked(lock, RW_LOCK_EX));
 
+#ifndef HAVE_ATOMIC_BUILTINS
 	mutex_enter(&(lock->mutex));
+#endif
 
 	lock->writer_thread = os_thread_get_curr_id();
 
 	lock->pass = 0;
 
+#ifndef HAVE_ATOMIC_BUILTINS
 	mutex_exit(&(lock->mutex));
+#endif
 }
 
 /**********************************************************************
@@ -342,6 +408,100 @@
 	const char*	file_name,/* in: file name where lock requested */
 	ulint		line)	/* in: line where requested */
 {
+#ifdef HAVE_ATOMIC_BUILTINS
+	os_thread_id_t	curr_thread	= os_thread_get_curr_id();
+
+	if (rw_lock_get_writer(lock) == RW_LOCK_NOT_LOCKED) {
+		/* try to lock writer */
+		if(__sync_sub_and_fetch(&(lock->writer),
+				RW_LOCK_NOT_LOCKED) == 0) {
+			/* success */
+			/* obtain RW_LOCK_WAIT_EX right */
+			lock->writer_thread = curr_thread;
+			lock->pass = pass;
+			lock->writer_is_wait_ex = TRUE;
+			/* 0 -> RW_LOCK_WAIT_EX */
+			__sync_fetch_and_add(&(lock->writer),
+				RW_LOCK_WAIT_EX);
+#ifdef UNIV_SYNC_DEBUG
+			rw_lock_add_debug_info(lock, pass, RW_LOCK_WAIT_EX,
+						file_name, line);
+#endif
+		} else {
+			/* fail */
+			__sync_fetch_and_add(&(lock->writer),
+				RW_LOCK_NOT_LOCKED);
+		}
+	}
+
+	if (!os_thread_eq(lock->writer_thread, curr_thread)) {
+		return(RW_LOCK_NOT_LOCKED);
+	}
+
+	switch(rw_lock_get_writer(lock)) {
+	    case RW_LOCK_WAIT_EX:
+		/* have right to try x-lock */
+		if (lock->lock_word == RW_LOCK_BIAS) {
+			/* try x-lock */
+			if(__sync_sub_and_fetch(&(lock->lock_word),
+					RW_LOCK_BIAS) == 0) {
+				/* success */
+				__sync_fetch_and_sub(&(lock->writer),
+					RW_LOCK_WAIT_EX);
+				lock->pass = pass;
+				lock->writer_is_wait_ex = FALSE;
+				__sync_fetch_and_add(&(lock->writer),
+					RW_LOCK_EX);
+				__sync_fetch_and_add(&(lock->writer_count),1);
+
+#ifdef UNIV_SYNC_DEBUG
+				rw_lock_remove_debug_info(lock, pass, RW_LOCK_WAIT_EX);
+				rw_lock_add_debug_info(lock, pass, RW_LOCK_EX,
+							file_name, line);
+#endif
+
+				lock->last_x_file_name = file_name;
+				lock->last_x_line = line;
+
+				/* Locking succeeded, we may return */
+				return(RW_LOCK_EX);
+			} else {
+				/* fail */
+				__sync_fetch_and_add(&(lock->lock_word),
+					RW_LOCK_BIAS);
+			}
+		}
+		/* There are readers, we have to wait */
+		return(RW_LOCK_WAIT_EX);
+
+		break;
+
+	    case RW_LOCK_EX:
+		/* already have x-lock */
+		if ((lock->pass == 0)&&(pass == 0)) {
+			__sync_fetch_and_add(&(lock->writer_count),1);
+
+#ifdef UNIV_SYNC_DEBUG
+			rw_lock_add_debug_info(lock, pass, RW_LOCK_EX, file_name,
+						line);
+#endif
+
+			lock->last_x_file_name = file_name;
+			lock->last_x_line = line;
+
+			/* Locking succeeded, we may return */
+			return(RW_LOCK_EX);
+		}
+
+		return(RW_LOCK_NOT_LOCKED);
+
+		break;
+
+	    default: /* ??? */
+		return(RW_LOCK_NOT_LOCKED);
+	}
+#else /* HAVE_ATOMIC_BUILTINS */
+
 #ifdef UNIV_SYNC_DEBUG
 	ut_ad(mutex_own(rw_lock_get_mutex(lock)));
 #endif /* UNIV_SYNC_DEBUG */
@@ -423,6 +583,7 @@
 		/* Locking succeeded, we may return */
 		return(RW_LOCK_EX);
 	}
+#endif /* HAVE_ATOMIC_BUILTINS */
 
 	/* Locking did not succeed */
 	return(RW_LOCK_NOT_LOCKED);
@@ -448,19 +609,33 @@
 	ulint		line)	/* in: line where requested */
 {
         ulint	index;  /* index of the reserved wait cell */
-        ulint	state;	/* lock state acquired */
+        ulint	state = RW_LOCK_NOT_LOCKED;	/* lock state acquired */
+#ifdef HAVE_ATOMIC_BUILTINS
+	ulint	prev_state = RW_LOCK_NOT_LOCKED;
+#endif
         ulint	i;	/* spin round count */
         
         ut_ad(rw_lock_validate(lock));
 
 lock_loop:
+	i = 0;
+
+#ifdef HAVE_ATOMIC_BUILTINS
+	prev_state = state;
+#else
         /* Acquire the mutex protecting the rw-lock fields */
 	mutex_enter_fast(&(lock->mutex));
+#endif
 
 	state = rw_lock_x_lock_low(lock, pass, file_name, line);
 		
+#ifdef HAVE_ATOMIC_BUILTINS
+	if (state != prev_state) i=0; /* if progress, reset counter. */
+#else
 	mutex_exit(&(lock->mutex));
+#endif
         
+spin_loop:
 	if (state == RW_LOCK_EX) {
 
 		return;	/* Locking succeeded */
@@ -468,10 +643,9 @@
 	} else if (state == RW_LOCK_NOT_LOCKED) {
 
  		/* Spin waiting for the writer field to become free */
-		i = 0;
 
-        	while (rw_lock_get_writer(lock) != RW_LOCK_NOT_LOCKED 
-               					&& i < SYNC_SPIN_ROUNDS) {
+        	while (i < SYNC_SPIN_ROUNDS
+			&& rw_lock_get_writer(lock) != RW_LOCK_NOT_LOCKED) {
         		if (srv_spin_wait_delay) {
 				ut_delay(ut_rnd_interval(0,
 							srv_spin_wait_delay));
@@ -485,9 +659,12 @@
         } else if (state == RW_LOCK_WAIT_EX) {
 
  		/* Spin waiting for the reader count field to become zero */
-		i = 0;
 
+#ifdef HAVE_ATOMIC_BUILTINS
+		while (lock->lock_word != RW_LOCK_BIAS
+#else
         	while (rw_lock_get_reader_count(lock) != 0 
+#endif
                					&& i < SYNC_SPIN_ROUNDS) {
         		if (srv_spin_wait_delay) {
 				ut_delay(ut_rnd_interval(0,
@@ -500,7 +677,6 @@
 			os_thread_yield();
 		}
         } else {
-		i = 0; /* Eliminate a compiler warning */
 		ut_error;
 	}	
 
@@ -516,16 +692,35 @@
         /* We try once again to obtain the lock. Acquire the mutex protecting
 	the rw-lock fields */
 
+#ifdef HAVE_ATOMIC_BUILTINS
+	prev_state = state;
+#else
 	mutex_enter(rw_lock_get_mutex(lock));
+#endif
 
 	state = rw_lock_x_lock_low(lock, pass, file_name, line);
 
+#ifdef HAVE_ATOMIC_BUILTINS
+	if (state != prev_state) i=0; /* if progress, reset counter. */
+#endif
+
 	if (state == RW_LOCK_EX) {
+#ifndef HAVE_ATOMIC_BUILTINS
 		mutex_exit(rw_lock_get_mutex(lock));
+#endif
 
 		return;	/* Locking succeeded */
 	}
 
+#ifdef HAVE_ATOMIC_BUILTINS
+	/* like sync0sync.c doing */
+	i++;
+
+	if (i < SYNC_SPIN_ROUNDS) {
+		goto spin_loop;
+	}
+#endif
+
 	rw_x_system_call_count++;
 
         sync_array_reserve_cell(sync_primary_wait_array,
@@ -541,9 +736,28 @@
 				file_name, line,
 				&index);
 
+#ifdef HAVE_ATOMIC_BUILTINS
+	rw_lock_set_x_waiters(lock, 1);
+
+	/* like sync0sync.c doing */
+	for (i = 0; i < 4; i++) {
+		prev_state = state;
+		state = rw_lock_x_lock_low(lock, pass, file_name, line);
+		if (state == RW_LOCK_EX) {
+			sync_array_free_cell(sync_primary_wait_array, index);
+			return; /* Locking succeeded */
+		}
+		if (state != prev_state) {
+			/* retry! */
+			sync_array_free_cell(sync_primary_wait_array, index);
+			goto lock_loop;
+		}
+	}
+#else
 	rw_lock_set_waiters(lock, 1);
 
 	mutex_exit(rw_lock_get_mutex(lock));
+#endif
 
 	if (srv_print_latch_waits) {
 		fprintf(stderr,
@@ -718,7 +932,9 @@
 	ut_ad(lock);
 	ut_ad(rw_lock_validate(lock));
 
+#ifndef HAVE_ATOMIC_BUILTINS
 	mutex_enter(&(lock->mutex));
+#endif
 
 	info = UT_LIST_GET_FIRST(lock->debug_list);
 
@@ -728,7 +944,9 @@
 		    && (info->pass == 0)
 		    && (info->lock_type == lock_type)) {
 
+#ifndef HAVE_ATOMIC_BUILTINS
 			mutex_exit(&(lock->mutex));
+#endif
 		    	/* Found! */
 
 		    	return(TRUE);
@@ -736,7 +954,9 @@
 
 		info = UT_LIST_GET_NEXT(list, info);
 	}
+#ifndef HAVE_ATOMIC_BUILTINS
 	mutex_exit(&(lock->mutex));
+#endif
 
 	return(FALSE);
 }
@@ -758,21 +978,25 @@
 	ut_ad(lock);
 	ut_ad(rw_lock_validate(lock));
 	
+#ifndef HAVE_ATOMIC_BUILTINS
 	mutex_enter(&(lock->mutex));
+#endif
 
 	if (lock_type == RW_LOCK_SHARED) {
 		if (lock->reader_count > 0) {
 			ret = TRUE;
 		}
 	} else if (lock_type == RW_LOCK_EX) {
-		if (lock->writer == RW_LOCK_EX) {
+		if (rw_lock_get_writer(lock) == RW_LOCK_EX) {
 			ret = TRUE;
 		}
 	} else {
 		ut_error;
 	}
 
+#ifndef HAVE_ATOMIC_BUILTINS
 	mutex_exit(&(lock->mutex));
+#endif
 
 	return(ret);
 }
@@ -801,16 +1025,31 @@
 
 		count++;
 
+#ifndef HAVE_ATOMIC_BUILTINS
 		mutex_enter(&(lock->mutex));
+#endif
 
 		if ((rw_lock_get_writer(lock) != RW_LOCK_NOT_LOCKED)
 		    || (rw_lock_get_reader_count(lock) != 0)
+#ifdef HAVE_ATOMIC_BUILTINS
+		    || (rw_lock_get_s_waiters(lock) != 0)
+		    || (rw_lock_get_x_waiters(lock) != 0)) {
+#else
 		    || (rw_lock_get_waiters(lock) != 0)) {
+#endif
 
 			fprintf(stderr, "RW-LOCK: %p ", lock);
 
+#ifdef HAVE_ATOMIC_BUILTINS
+			if (rw_lock_get_s_waiters(lock)) {
+				fputs(" s_waiters for the lock exist,", stderr);
+			}
+			if (rw_lock_get_x_waiters(lock)) {
+				fputs(" x_waiters for the lock exist\n", stderr);
+#else
 			if (rw_lock_get_waiters(lock)) {
 				fputs(" Waiters for the lock exist\n", stderr);
+#endif
 			} else {
 				putc('\n', stderr);
 			}
@@ -822,7 +1061,9 @@
 			}
 		}
 
+#ifndef HAVE_ATOMIC_BUILTINS
 		mutex_exit(&(lock->mutex));
+#endif
 		lock = UT_LIST_GET_NEXT(list, lock);
 	}
 
@@ -847,10 +1088,23 @@
 
 	if ((rw_lock_get_writer(lock) != RW_LOCK_NOT_LOCKED)
 	    || (rw_lock_get_reader_count(lock) != 0)
+#ifdef HAVE_ATOMIC_BUILTINS
+	    || (rw_lock_get_s_waiters(lock) != 0)
+	    || (rw_lock_get_x_waiters(lock) != 0)) {
+#else
 	    || (rw_lock_get_waiters(lock) != 0)) {
+#endif
 
+#ifdef HAVE_ATOMIC_BUILTINS
+		if (rw_lock_get_s_waiters(lock)) {
+			fputs(" s_waiters for the lock exist,", stderr);
+		}
+		if (rw_lock_get_x_waiters(lock)) {
+			fputs(" x_waiters for the lock exist\n", stderr);
+#else
 		if (rw_lock_get_waiters(lock)) {
 			fputs(" Waiters for the lock exist\n", stderr);
+#endif
 		} else {
 			putc('\n', stderr);
 		}
@@ -909,14 +1163,18 @@
 	lock = UT_LIST_GET_FIRST(rw_lock_list);
 
 	while (lock != NULL) {
+#ifndef HAVE_ATOMIC_BUILTINS
 		mutex_enter(rw_lock_get_mutex(lock));
+#endif
 
 		if ((rw_lock_get_writer(lock) != RW_LOCK_NOT_LOCKED)
 				|| (rw_lock_get_reader_count(lock) != 0)) {
 			count++;
 		}
 
+#ifndef HAVE_ATOMIC_BUILTINS
 		mutex_exit(rw_lock_get_mutex(lock));
+#endif
 		lock = UT_LIST_GET_NEXT(list, lock);
 	}