From 52ac02e4d7f3dc6035fb429a557276c9f267439a Mon Sep 17 00:00:00 2001
From: kettenis <kettenis@openbsd.org>
Date: Thu, 16 May 2024 09:30:03 +0000
Subject: [PATCH] Stop treating IPL_NONE mutexes special in MULTIPROCESSOR
 kernels.  While in theory these are safe to use in code that runs under the
 kernel lock they are nasty trips when converting code to run without the
 kernel lock.

ok mpi@, claudio@
---
 sys/arch/hppa/include/mutex.h | 12 +-----------
 sys/arch/m88k/include/mutex.h | 21 ++++-----------------
 sys/sys/mutex.h               | 30 +++++++++++++++---------------
 3 files changed, 20 insertions(+), 43 deletions(-)

diff --git a/sys/arch/hppa/include/mutex.h b/sys/arch/hppa/include/mutex.h
index 0aa8d1b3230..a7277931964 100644
--- a/sys/arch/hppa/include/mutex.h
+++ b/sys/arch/hppa/include/mutex.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: mutex.h,v 1.9 2018/01/13 15:18:11 mpi Exp $	*/
+/*	$OpenBSD: mutex.h,v 1.10 2024/05/16 09:30:03 kettenis Exp $	*/
 
 /*
  * Copyright (c) 2004 Artur Grabowski <art@openbsd.org>
@@ -45,16 +45,7 @@ struct mutex {
 #endif
 };
 
-/*
- * To prevent lock ordering problems with the kernel lock, we need to
- * make sure we block all interrupts that can grab the kernel lock.
- * The simplest way to achieve this is to make sure mutexes always
- * raise the interrupt priority level to the highest level that has
- * interrupts that grab the kernel lock.
- */
 #ifdef MULTIPROCESSOR
-#define __MUTEX_IPL(ipl) \
-    (((ipl) > IPL_NONE && (ipl) < IPL_MPFLOOR) ? IPL_MPFLOOR : (ipl))
 #ifdef WITNESS
 #define MUTEX_INITIALIZER_FLAGS(ipl, name, flags) \
 	{ MUTEX_UNLOCKED, __MUTEX_IPL((ipl)), 0, NULL, \
@@ -64,7 +55,6 @@ struct mutex {
 	{ MUTEX_UNLOCKED, __MUTEX_IPL((ipl)), 0, NULL }
 #endif /* WITNESS */
 #else /* MULTIPROCESSOR */
-#define __MUTEX_IPL(ipl) (ipl)
 #define MUTEX_INITIALIZER_FLAGS(ipl, name, flags) \
 	{ __MUTEX_IPL((ipl)), 0, NULL }
 #endif /* MULTIPROCESSOR */
diff --git a/sys/arch/m88k/include/mutex.h b/sys/arch/m88k/include/mutex.h
index 5752a427f42..61b1f0dd826 100644
--- a/sys/arch/m88k/include/mutex.h
+++ b/sys/arch/m88k/include/mutex.h
@@ -1,6 +1,4 @@
-#ifndef _M88K_MUTEX_H_
-#define _M88K_MUTEX_H_
-/*	$OpenBSD: mutex.h,v 1.8 2020/05/26 11:55:10 aoyama Exp $	*/
+/*	$OpenBSD: mutex.h,v 1.9 2024/05/16 09:30:03 kettenis Exp $	*/
 
 /*
  * Copyright (c) 2005, Miodrag Vallat.
@@ -27,6 +25,9 @@
  * POSSIBILITY OF SUCH DAMAGE.
  */
 
+#ifndef _M88K_MUTEX_H_
+#define _M88K_MUTEX_H_
+
 #include <sys/_lock.h>
 
 struct mutex {
@@ -39,20 +40,6 @@ struct mutex {
 #endif
 };
 
-/*
- * To prevent lock ordering problems with the kernel lock, we need to
- * make sure we block all interrupts that can grab the kernel lock.
- * The simplest way to achieve this is to make sure mutexes always
- * raise the interrupt priority level to the highest level that has
- * interrupts that grab the kernel lock.
- */
-#ifdef MULTIPROCESSOR
-#define __MUTEX_IPL(ipl) \
-    (((ipl) > IPL_NONE && (ipl) < IPL_MPFLOOR) ? IPL_MPFLOOR : (ipl))
-#else
-#define __MUTEX_IPL(ipl) (ipl)
-#endif
-
 #ifdef WITNESS
 #define	MUTEX_INITIALIZER_FLAGS(ipl, name, flags) \
 	{ 0, __MUTEX_IPL((ipl)), IPL_NONE, NULL, \
diff --git a/sys/sys/mutex.h b/sys/sys/mutex.h
index cff33404c3c..960299fa941 100644
--- a/sys/sys/mutex.h
+++ b/sys/sys/mutex.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: mutex.h,v 1.21 2024/03/26 18:18:30 bluhm Exp $	*/
+/*	$OpenBSD: mutex.h,v 1.22 2024/05/16 09:30:03 kettenis Exp $	*/
 
 /*
  * Copyright (c) 2004 Artur Grabowski <art@openbsd.org>
@@ -33,6 +33,20 @@
  * "mtx_enter(foo); mtx_enter(bar); mtx_leave(foo); mtx_leave(bar);"
  */
 
+/*
+ * To prevent lock ordering problems with the kernel lock, we need to
+ * make sure we block all interrupts that can grab the kernel lock.
+ * The simplest way to achieve this is to make sure mutexes always
+ * raise the interrupt priority level to the highest level that has
+ * interrupts that grab the kernel lock.
+ */
+#ifdef MULTIPROCESSOR
+#define __MUTEX_IPL(ipl) \
+	(((ipl) < IPL_MPFLOOR) ? IPL_MPFLOOR : (ipl))
+#else
+#define __MUTEX_IPL(ipl) (ipl)
+#endif
+
 #include <machine/mutex.h>
 
 #ifdef __USE_MI_MUTEX
@@ -48,20 +62,6 @@ struct mutex {
 #endif
 };
 
-/*
- * To prevent lock ordering problems with the kernel lock, we need to
- * make sure we block all interrupts that can grab the kernel lock.
- * The simplest way to achieve this is to make sure mutexes always
- * raise the interrupt priority level to the highest level that has
- * interrupts that grab the kernel lock.
- */
-#ifdef MULTIPROCESSOR
-#define __MUTEX_IPL(ipl) \
-    (((ipl) > IPL_NONE && (ipl) < IPL_MPFLOOR) ? IPL_MPFLOOR : (ipl))
-#else
-#define __MUTEX_IPL(ipl) (ipl)
-#endif
-
 #ifdef WITNESS
 #define MUTEX_INITIALIZER_FLAGS(ipl, name, flags) \
 	{ NULL, __MUTEX_IPL((ipl)), IPL_NONE, MTX_LO_INITIALIZER(name, flags) }
-- 
2.20.1