Index: arch/i386/gen/_atomic_lock.c
===================================================================
RCS file: /cvs/src/lib/libc/arch/i386/gen/_atomic_lock.c,v
diff -u -p -r1.1 _atomic_lock.c
--- arch/i386/gen/_atomic_lock.c	15 Aug 2017 06:13:24 -0000	1.1
+++ arch/i386/gen/_atomic_lock.c	12 Jul 2025 04:57:21 -0000
@@ -17,7 +17,7 @@ _atomic_lock(volatile _atomic_lock_t *lo
 	 * a local variable containing the locked state.
 	 */
 	old = _ATOMIC_LOCK_LOCKED;
-	__asm__("xchg %0,(%2)"
+	__asm__("lock xchg %0,(%2)"
 		: "=r" (old)
 		: "0"  (old), "r"  (lock));
 
Index: arch/amd64/gen/_atomic_lock.c
===================================================================
RCS file: /cvs/src/lib/libc/arch/amd64/gen/_atomic_lock.c,v
diff -u -p -r1.1 _atomic_lock.c
--- arch/amd64/gen/_atomic_lock.c	15 Aug 2017 06:13:24 -0000	1.1
+++ arch/amd64/gen/_atomic_lock.c	12 Jul 2025 04:57:21 -0000
@@ -18,7 +18,7 @@ _atomic_lock(volatile _atomic_lock_t *lo
 	 * a local variable containing the locked state.
 	 */
 	old = _ATOMIC_LOCK_LOCKED;
-	__asm__("xchg %0,(%2)"
+	__asm__("lock xchg %0,(%2)"
 		: "=r" (old)
 		: "0"  (old), "r"  (lock));