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/* 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 */
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