locking/mutex: split out mutex_types.h

Trimming down sched.h dependencies: we don't want to include more than
the base types.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Will Deacon <will@kernel.org>
Cc: Waiman Long <longman@redhat.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

1 files changed, 71 insertions, 0 deletions

diff --git a/include/linux/mutex_types.h b/include/linux/mutex_types.h
new file mode 100644
index 000000000000..fdf7f515fde8
--- /dev/null
+++ b/include/linux/mutex_types.h
@@ -0,0 +1,71 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __LINUX_MUTEX_TYPES_H
+#define __LINUX_MUTEX_TYPES_H
+
+#include <linux/atomic.h>
+#include <linux/lockdep_types.h>
+#include <linux/osq_lock.h>
+#include <linux/spinlock_types.h>
+#include <linux/types.h>
+
+#ifndef CONFIG_PREEMPT_RT
+
+/*
+ * Simple, straightforward mutexes with strict semantics:
+ *
+ * - only one task can hold the mutex at a time
+ * - only the owner can unlock the mutex
+ * - multiple unlocks are not permitted
+ * - recursive locking is not permitted
+ * - a mutex object must be initialized via the API
+ * - a mutex object must not be initialized via memset or copying
+ * - task may not exit with mutex held
+ * - memory areas where held locks reside must not be freed
+ * - held mutexes must not be reinitialized
+ * - mutexes may not be used in hardware or software interrupt
+ *   contexts such as tasklets and timers
+ *
+ * These semantics are fully enforced when DEBUG_MUTEXES is
+ * enabled. Furthermore, besides enforcing the above rules, the mutex
+ * debugging code also implements a number of additional features
+ * that make lock debugging easier and faster:
+ *
+ * - uses symbolic names of mutexes, whenever they are printed in debug output
+ * - point-of-acquire tracking, symbolic lookup of function names
+ * - list of all locks held in the system, printout of them
+ * - owner tracking
+ * - detects self-recursing locks and prints out all relevant info
+ * - detects multi-task circular deadlocks and prints out all affected
+ *   locks and tasks (and only those tasks)
+ */
+struct mutex {
+	atomic_long_t		owner;
+	raw_spinlock_t		wait_lock;
+#ifdef CONFIG_MUTEX_SPIN_ON_OWNER
+	struct optimistic_spin_queue osq; /* Spinner MCS lock */
+#endif
+	struct list_head	wait_list;
+#ifdef CONFIG_DEBUG_MUTEXES
+	void			*magic;
+#endif
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+	struct lockdep_map	dep_map;
+#endif
+};
+
+#else /* !CONFIG_PREEMPT_RT */
+/*
+ * Preempt-RT variant based on rtmutexes.
+ */
+#include <linux/rtmutex.h>
+
+struct mutex {
+	struct rt_mutex_base	rtmutex;
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+	struct lockdep_map	dep_map;
+#endif
+};
+
+#endif /* CONFIG_PREEMPT_RT */
+
+#endif /* __LINUX_MUTEX_TYPES_H */