/* SPDX-License-Identifier: GPL-2.0 *//* * Mutexes: blocking mutual exclusion locks * * started by Ingo Molnar: * *  Copyright (C) 2004, 2005, 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com> */#ifndef CONFIG_PREEMPT_RT/* * This is the control structure for tasks blocked on mutex, which resides * on the blocked task's kernel stack: */struct mutex_waiter {	struct list_head	list;	struct task_struct	*task;	struct ww_acquire_ctx	*ww_ctx;#ifdef CONFIG_DEBUG_MUTEXES	void			*magic;#endif}; /* * @owner: contains: 'struct task_struct *' to the current lock owner, * NULL means not owned. Since task_struct pointers are aligned at * at least L1_CACHE_BYTES, we have low bits to store extra state. * * Bit0 indicates a non-empty waiter list; unlock must issue a wakeup. * Bit1 indicates unlock needs to hand the lock to the top-waiter * Bit2 indicates handoff has been done and we're waiting for pickup. */#define MUTEX_FLAG_WAITERS	0x01#define MUTEX_FLAG_HANDOFF	0x02#define MUTEX_FLAG_PICKUP	0x04 #define MUTEX_FLAGS		0x07 /* * Internal helper function; C doesn't allow us to hide it :/ * * DO NOT USE (outside of mutex & scheduler code). */static inline struct task_struct *__mutex_owner(struct mutex *lock){	if (!lock)		return NULL;	return (struct task_struct *)(atomic_long_read(&lock->owner) & ~MUTEX_FLAGS);} #ifdef CONFIG_DEBUG_MUTEXESextern void debug_mutex_lock_common(struct mutex *lock,				    struct mutex_waiter *waiter);extern void debug_mutex_wake_waiter(struct mutex *lock,				    struct mutex_waiter *waiter);extern void debug_mutex_free_waiter(struct mutex_waiter *waiter);extern void debug_mutex_add_waiter(struct mutex *lock,				   struct mutex_waiter *waiter,				   struct task_struct *task);extern void debug_mutex_remove_waiter(struct mutex *lock, struct mutex_waiter *waiter,				      struct task_struct *task);extern void debug_mutex_unlock(struct mutex *lock);extern void debug_mutex_init(struct mutex *lock);#else /* CONFIG_DEBUG_MUTEXES */# define debug_mutex_lock_common(lock, waiter)		do { } while (0)# define debug_mutex_wake_waiter(lock, waiter)		do { } while (0)# define debug_mutex_free_waiter(waiter)		do { } while (0)# define debug_mutex_add_waiter(lock, waiter, ti)	do { } while (0)# define debug_mutex_remove_waiter(lock, waiter, ti)	do { } while (0)# define debug_mutex_unlock(lock)			do { } while (0)# define debug_mutex_init(lock)				do { } while (0)#endif /* !CONFIG_DEBUG_MUTEXES */#endif /* CONFIG_PREEMPT_RT */