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+/* $OpenBSD: mutex.h,v 1.18 2019/04/23 13:35:12 visa Exp $ */
+
+/*
+ * Copyright (c) 2004 Artur Grabowski <art@openbsd.org>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#ifndef _SYS_MUTEX_H_
+#define _SYS_MUTEX_H_
+
+/*
+ * A mutex is:
+ * - owned by a cpu.
+ * - non-recursive.
+ * - spinning.
+ * - not providing mutual exclusion between processes, only cpus.
+ * - providing interrupt blocking when necessary.
+ *
+ * Different mutexes can be nested, but not interleaved. This is ok:
+ * "mtx_enter(foo); mtx_enter(bar); mtx_leave(bar); mtx_leave(foo);"
+ * This is _not_ ok:
+ * "mtx_enter(foo); mtx_enter(bar); mtx_leave(foo); mtx_leave(bar);"
+ */
+
+#include <machine/mutex.h>
+
+#ifdef __USE_MI_MUTEX
+
+#include <sys/_lock.h>
+
+struct mutex {
+ volatile void *mtx_owner;
+ int mtx_wantipl;
+ int mtx_oldipl;
+#ifdef WITNESS
+ struct lock_object mtx_lock_obj;
+#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) }
+#else
+#define MUTEX_INITIALIZER_FLAGS(ipl, name, flags) \
+ { NULL, __MUTEX_IPL((ipl)), IPL_NONE }
+#endif
+
+void __mtx_init(struct mutex *, int);
+#define _mtx_init(mtx, ipl) __mtx_init((mtx), __MUTEX_IPL((ipl)))
+
+#ifdef DIAGNOSTIC
+#define MUTEX_ASSERT_LOCKED(mtx) do { \
+ if (((mtx)->mtx_owner != curcpu()) && !(panicstr || db_active)) \
+ panic("mutex %p not held in %s", (mtx), __func__); \
+} while (0)
+
+#define MUTEX_ASSERT_UNLOCKED(mtx) do { \
+ if (((mtx)->mtx_owner == curcpu()) && !(panicstr || db_active)) \
+ panic("mutex %p held in %s", (mtx), __func__); \
+} while (0)
+#else
+#define MUTEX_ASSERT_LOCKED(mtx) do { } while (0)
+#define MUTEX_ASSERT_UNLOCKED(mtx) do { } while (0)
+#endif
+
+#define MUTEX_LOCK_OBJECT(mtx) (&(mtx)->mtx_lock_obj)
+#define MUTEX_OLDIPL(mtx) (mtx)->mtx_oldipl
+
+#endif /* __USE_MI_MUTEX */
+
+
+#define MTX_LO_FLAGS(flags) \
+ ((!((flags) & MTX_NOWITNESS) ? LO_WITNESS : 0) | \
+ ((flags) & MTX_DUPOK ? LO_DUPOK : 0) | \
+ LO_INITIALIZED | (LO_CLASS_MUTEX << LO_CLASSSHIFT))
+
+#define __MTX_STRING(x) #x
+#define __MTX_S(x) __MTX_STRING(x)
+#define __MTX_NAME __FILE__ ":" __MTX_S(__LINE__)
+
+#define MTX_LO_INITIALIZER(name, flags) \
+ { .lo_type = &(const struct lock_type){ .lt_name = __MTX_NAME }, \
+ .lo_name = (name), \
+ .lo_flags = MTX_LO_FLAGS(flags) }
+
+#define MTX_NOWITNESS 0x01
+#define MTX_DUPOK 0x02
+
+#define MUTEX_INITIALIZER(ipl) \
+ MUTEX_INITIALIZER_FLAGS(ipl, __MTX_NAME, 0)
+
+/*
+ * Some architectures need to do magic for the ipl, so they need a macro.
+ */
+#ifndef _mtx_init
+void _mtx_init(struct mutex *, int);
+#endif
+
+void mtx_enter(struct mutex *);
+int mtx_enter_try(struct mutex *);
+void mtx_leave(struct mutex *);
+
+#define mtx_init(m, ipl) mtx_init_flags(m, ipl, NULL, 0)
+
+#ifdef WITNESS
+
+void _mtx_init_flags(struct mutex *, int, const char *, int,
+ const struct lock_type *);
+
+#define mtx_init_flags(m, ipl, name, flags) do { \
+ static const struct lock_type __lock_type = { .lt_name = #m }; \
+ _mtx_init_flags(m, ipl, name, flags, &__lock_type); \
+} while (0)
+
+#else /* WITNESS */
+
+#define mtx_init_flags(m, ipl, name, flags) do { \
+ (void)(name); (void)(flags); \
+ _mtx_init(m, ipl); \
+} while (0)
+
+#define _mtx_init_flags(m,i,n,f,t) _mtx_init(m,i)
+
+#endif /* WITNESS */
+
+#if defined(_KERNEL) && defined(DDB)
+
+struct db_mutex {
+ struct cpu_info *mtx_owner;
+ unsigned long mtx_intr_state;
+};
+
+#define DB_MUTEX_INITIALIZER { NULL, 0 }
+
+void db_mtx_enter(struct db_mutex *);
+void db_mtx_leave(struct db_mutex *);
+
+#endif /* _KERNEL && DDB */
+
+#endif