/* * RT Mutexes: blocking mutual exclusion locks with PI support * * started by Ingo Molnar and Thomas Gleixner: * * Copyright (C) 2004-2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com> * Copyright (C) 2006, Timesys Corp., Thomas Gleixner <tglx@timesys.com> * * This file contains the private data structure and API definitions. */ #ifndef __KERNEL_RTMUTEX_COMMON_H #define __KERNEL_RTMUTEX_COMMON_H #include <linux/rtmutex.h> /* * The rtmutex in kernel tester is independent of rtmutex debugging. We * call schedule_rt_mutex_test() instead of schedule() for the tasks which * belong to the tester. That way we can delay the wakeup path of those * threads to provoke lock stealing and testing of complex boosting scenarios. */ #ifdef CONFIG_RT_MUTEX_TESTER extern void schedule_rt_mutex_test(struct rt_mutex *lock); #define schedule_rt_mutex(_lock) \ do { \ if (!(current->flags & PF_MUTEX_TESTER)) \ schedule(); \ else \ schedule_rt_mutex_test(_lock); \ } while (0) #else # define schedule_rt_mutex(_lock) schedule() #endif /* * This is the control structure for tasks blocked on a rt_mutex, * which is allocated on the kernel stack on of the blocked task. * * @list_entry: pi node to enqueue into the mutex waiters list * @pi_list_entry: pi node to enqueue into the mutex owner waiters list * @task: task reference to the blocked task */ struct rt_mutex_waiter { struct plist_node list_entry; struct plist_node pi_list_entry; struct task_struct *task; struct rt_mutex *lock; #ifdef CONFIG_DEBUG_RT_MUTEXES unsigned long ip; pid_t deadlock_task_pid; struct rt_mutex *deadlock_lock; #endif }; /* * Various helpers to access the waiters-plist: */ static inline int rt_mutex_has_waiters(struct rt_mutex *lock) { return !plist_head_empty(&lock->wait_list); } static inline struct rt_mutex_waiter * rt_mutex_top_waiter(struct rt_mutex *lock) { struct rt_mutex_waiter *w; w = plist_first_entry(&lock->wait_list, struct rt_mutex_waiter, list_entry); BUG_ON(w->lock != lock); return w; } static inline int task_has_pi_waiters(struct task_struct *p) { return !plist_head_empty(&p->pi_waiters); } static inline struct rt_mutex_waiter * task_top_pi_waiter(struct task_struct *p) { return plist_first_entry(&p->pi_waiters, struct rt_mutex_waiter, pi_list_entry); } /* * lock->owner state tracking: */ #define RT_MUTEX_OWNER_PENDING 1UL #define RT_MUTEX_HAS_WAITERS 2UL #define RT_MUTEX_OWNER_MASKALL 3UL static inline struct task_struct *rt_mutex_owner(struct rt_mutex *lock) { return (struct task_struct *) ((unsigned long)lock->owner & ~RT_MUTEX_OWNER_MASKALL); } static inline struct task_struct *rt_mutex_real_owner(struct rt_mutex *lock) { return (struct task_struct *) ((unsigned long)lock->owner & ~RT_MUTEX_HAS_WAITERS); } static inline unsigned long rt_mutex_owner_pending(struct rt_mutex *lock) { return (unsigned long)lock->owner & RT_MUTEX_OWNER_PENDING; } /* * We can speed up the acquire/release, if the architecture * supports cmpxchg and if there's no debugging state to be set up */ #if defined(__HAVE_ARCH_CMPXCHG) && !defined(CONFIG_DEBUG_RT_MUTEXES) # define rt_mutex_cmpxchg(l,c,n) (cmpxchg(&l->owner, c, n) == c) static inline void mark_rt_mutex_waiters(struct rt_mutex *lock) { unsigned long owner, *p = (unsigned long *) &lock->owner; do { owner = *p; } while (cmpxchg(p, owner, owner | RT_MUTEX_HAS_WAITERS) != owner); } #else # define rt_mutex_cmpxchg(l,c,n) (0) static inline void mark_rt_mutex_waiters(struct rt_mutex *lock) { lock->owner = (struct task_struct *) ((unsigned long)lock->owner | RT_MUTEX_HAS_WAITERS); } #endif /* * PI-futex support (proxy locking functions, etc.): */ extern struct task_struct *rt_mutex_next_owner(struct rt_mutex *lock); extern void rt_mutex_init_proxy_locked(struct rt_mutex *lock, struct task_struct *proxy_owner); extern void rt_mutex_proxy_unlock(struct rt_mutex *lock, struct task_struct *proxy_owner); extern void rt_mutex_set_owner(struct rt_mutex *lock, struct task_struct *owner, unsigned long mask); extern void __rt_mutex_adjust_prio(struct task_struct *task); extern int rt_mutex_adjust_prio_chain(struct task_struct *task, int deadlock_detect, struct rt_mutex *orig_lock, struct rt_mutex_waiter *orig_waiter, struct task_struct *top_task); extern void remove_waiter(struct rt_mutex *lock, struct rt_mutex_waiter *waiter); #endif