diff options
Diffstat (limited to 'sys/arch/i386/include')
| -rw-r--r-- | sys/arch/i386/include/mutex.h | 21 |
1 files changed, 19 insertions, 2 deletions
diff --git a/sys/arch/i386/include/mutex.h b/sys/arch/i386/include/mutex.h index de340320e57..b2fb16802bb 100644 --- a/sys/arch/i386/include/mutex.h +++ b/sys/arch/i386/include/mutex.h @@ -1,4 +1,4 @@ -/* $OpenBSD: mutex.h,v 1.4 2011/03/23 16:54:35 pirofti Exp $ */ +/* $OpenBSD: mutex.h,v 1.5 2013/07/10 21:31:12 kettenis Exp $ */ /* * Copyright (c) 2004 Artur Grabowski <art@openbsd.org> @@ -38,7 +38,24 @@ struct mutex { void *mtx_owner; }; -#define MUTEX_INITIALIZER(IPL) { 0, (IPL), 0, NULL } +/* + * 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_VM) ? IPL_VM : (ipl)) +#else +#define __MUTEX_IPL(ipl) (ipl) +#endif + +#define MUTEX_INITIALIZER(ipl) { 0, __MUTEX_IPL((ipl)), 0, NULL } + +void __mtx_init(struct mutex *, int); +#define mtx_init(mtx, ipl) __mtx_init((mtx), __MUTEX_IPL((ipl))) #define MUTEX_ASSERT_LOCKED(mtx) do { \ if ((mtx)->mtx_lock != 1 || \ |