Promote __mp_lock_spinout to long

This lets us implement larger MP_LOCKDEBUG thresholds on very fast
machines, so that we can tell transient contentions apart from actual
lockups. deraadt@ expressed concerns that bumping the threshold might
hide actual problems, but this diff doesn't change the threshold. As
mentioned by mpi@ and claudio@ MP_LOCKDEBUG is a very crude tool, but
it's the only tool we have right now.

ok miod@ claudio@

Author: jcourreges

sys/arch/amd64/amd64/pmap.c

@@ -1,4 +1,4 @@
-/*	$OpenBSD: pmap.c,v 1.179 2025/06/18 15:05:53 jca Exp $	*/
+/*	$OpenBSD: pmap.c,v 1.180 2025/06/19 12:01:08 jca Exp $	*/
 /*	$NetBSD: pmap.c,v 1.3 2003/05/08 18:13:13 thorpej Exp $	*/
 
 /*
@@ -3208,7 +3208,7 @@ pmap_start_tlb_shoot(long wait, const char *func)
 
 	while (atomic_cas_ulong(&tlb_shoot_wait, 0, wait) != 0) {
 #ifdef MP_LOCKDEBUG
-		int nticks = __mp_lock_spinout;
+		long nticks = __mp_lock_spinout;
 #endif
 		while (tlb_shoot_wait != 0) {
 			CPU_BUSY_CYCLE();
@@ -3421,7 +3421,7 @@ void
 pmap_tlb_shootwait(void)
 {
 #ifdef MP_LOCKDEBUG
-	int nticks = __mp_lock_spinout;
+	long nticks = __mp_lock_spinout;
 #endif
 	while (tlb_shoot_wait != 0) {
 		CPU_BUSY_CYCLE();

sys/arch/amd64/amd64/vmm_machdep.c

@@ -1,4 +1,4 @@
-/* $OpenBSD: vmm_machdep.c,v 1.58 2025/06/18 15:05:53 jca Exp $ */
+/* $OpenBSD: vmm_machdep.c,v 1.59 2025/06/19 12:01:08 jca Exp $ */
 /*
  * Copyright (c) 2014 Mike Larkin <[email protected]>
  *
@@ -635,7 +635,7 @@ vmm_start(void)
 	struct cpu_info *ci;
 	CPU_INFO_ITERATOR cii;
 #ifdef MP_LOCKDEBUG
-	int nticks;
+	long nticks;
 #endif /* MP_LOCKDEBUG */
 #endif /* MULTIPROCESSOR */
 
@@ -695,7 +695,7 @@ vmm_stop(void)
 	struct cpu_info *ci;
 	CPU_INFO_ITERATOR cii;
 #ifdef MP_LOCKDEBUG
-	int nticks;
+	long nticks;
 #endif /* MP_LOCKDEBUG */
 #endif /* MULTIPROCESSOR */
 
@@ -868,7 +868,7 @@ static int
 vmx_remote_vmclear(struct cpu_info *ci, struct vcpu *vcpu)
 {
 #ifdef MP_LOCKDEBUG
-	int nticks = __mp_lock_spinout;
+	long nticks = __mp_lock_spinout;
 #endif /* MP_LOCKDEBUG */
 
 	rw_enter_write(&ci->ci_vmcs_lock);

sys/arch/hppa/hppa/lock_machdep.c

@@ -1,4 +1,4 @@
-/*	$OpenBSD: lock_machdep.c,v 1.16 2025/06/18 15:05:53 jca Exp $	*/
+/*	$OpenBSD: lock_machdep.c,v 1.17 2025/06/19 12:01:08 jca Exp $	*/
 
 /*
  * Copyright (c) 2007 Artur Grabowski <[email protected]>
@@ -79,7 +79,7 @@ __mp_lock_spin(struct __mp_lock *mpl)
 	while (mpl->mpl_count != 0)
 		CPU_BUSY_CYCLE();
 #else
-	int nticks = __mp_lock_spinout;
+	long nticks = __mp_lock_spinout;
 
 	while (mpl->mpl_count != 0 && --nticks > 0)
 		CPU_BUSY_CYCLE();

sys/arch/m88k/m88k/mutex.c

@@ -1,4 +1,4 @@
-/*	$OpenBSD: mutex.c,v 1.2 2025/06/18 15:05:53 jca Exp $	*/
+/*	$OpenBSD: mutex.c,v 1.3 2025/06/19 12:01:08 jca Exp $	*/
 
 /*
  * Copyright (c) 2020 Miodrag Vallat
@@ -52,7 +52,7 @@ mtx_enter(struct mutex *mtx)
 {
 	struct schedstate_percpu *spc = &curcpu()->ci_schedstate;
 #ifdef MP_LOCKDEBUG
-	int nticks = __mp_lock_spinout;
+	long nticks = __mp_lock_spinout;
 #endif
 
 	WITNESS_CHECKORDER(MUTEX_LOCK_OBJECT(mtx),

sys/arch/powerpc/powerpc/lock_machdep.c

@@ -1,4 +1,4 @@
-/*	$OpenBSD: lock_machdep.c,v 1.13 2025/06/18 15:05:53 jca Exp $	*/
+/*	$OpenBSD: lock_machdep.c,v 1.14 2025/06/19 12:01:08 jca Exp $	*/
 
 /*
  * Copyright (c) 2021 George Koehler <[email protected]>
@@ -51,7 +51,7 @@ __ppc_lock_spin(struct __ppc_lock *mpl)
 	while (mpl->mpl_cpu != NULL)
 		CPU_BUSY_CYCLE();
 #else
-	int nticks = __mp_lock_spinout;
+	long nticks = __mp_lock_spinout;
 
 	while (mpl->mpl_cpu != NULL && --nticks > 0)
 		CPU_BUSY_CYCLE();

sys/kern/kern_lock.c

@@ -1,4 +1,4 @@
-/*	$OpenBSD: kern_lock.c,v 1.79 2025/06/10 08:56:21 mpi Exp $	*/
+/*	$OpenBSD: kern_lock.c,v 1.80 2025/06/19 12:01:08 jca Exp $	*/
 
 /*
  * Copyright (c) 2017 Visa Hankala
@@ -33,8 +33,11 @@
 #error "MP_LOCKDEBUG requires DDB"
 #endif
 
-/* CPU-dependent timing, this needs to be settable from ddb. */
-int __mp_lock_spinout = INT_MAX;
+/*
+ * CPU-dependent timing, this needs to be settable from ddb.
+ * Use a "long" to allow larger thresholds on fast 64 bits machines.
+ */
+long __mp_lock_spinout = 1L * INT_MAX;
 #endif /* MP_LOCKDEBUG */
 
 extern int ncpusfound;
@@ -124,7 +127,7 @@ __mp_lock_spin(struct __mp_lock *mpl, u_int me)
 {
 	struct schedstate_percpu *spc = &curcpu()->ci_schedstate;
 #ifdef MP_LOCKDEBUG
-	int nticks = __mp_lock_spinout;
+	long nticks = __mp_lock_spinout;
 #endif
 
 	spc->spc_spinning++;

sys/sys/systm.h

@@ -1,4 +1,4 @@
-/*	$OpenBSD: systm.h,v 1.175 2025/06/18 15:05:53 jca Exp $	*/
+/*	$OpenBSD: systm.h,v 1.176 2025/06/19 12:01:08 jca Exp $	*/
 /*	$NetBSD: systm.h,v 1.50 1996/06/09 04:55:09 briggs Exp $	*/
 
 /*-
@@ -108,7 +108,7 @@ extern struct vnode *swapdev_vp;/* vnode equivalent to above */
 extern int nowake;		/* dead wakeup(9) channel */
 
 #ifdef MP_LOCKDEBUG
-extern int __mp_lock_spinout;
+extern long __mp_lock_spinout;
 #endif
 
 struct proc;