Commit 4957089a authored by Alexei Starovoitov's avatar Alexei Starovoitov Committed by Vlastimil Babka
Browse files

locking/local_lock: Introduce local_lock_is_locked(). 



Introduce local_lock_is_locked() that returns true when
given local_lock is locked by current cpu (in !PREEMPT_RT) or
by current task (in PREEMPT_RT).
The goal is to detect a deadlock by the caller.

Reviewed-by: default avatarSebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Signed-off-by: default avatarVlastimil Babka <vbabka@suse.cz>
parent 4ec1a08d

include/linux/local_lock.h

+2 −0
Original line number Diff line number Diff line
@@ -66,6 +66,8 @@ 
 */

#define local_trylock(lock)		__local_trylock(this_cpu_ptr(lock))



#define local_lock_is_locked(lock)	__local_lock_is_locked(lock)



/**

 * local_trylock_irqsave - Try to acquire a per CPU local lock, save and disable

 *			   interrupts if acquired

include/linux/local_lock_internal.h

+7 −0
Original line number Diff line number Diff line
@@ -165,6 +165,9 @@ do { \ 
		!!tl;						\

	})



/* preemption or migration must be disabled before calling __local_lock_is_locked */

#define __local_lock_is_locked(lock) READ_ONCE(this_cpu_ptr(lock)->acquired)



#define __local_lock_release(lock)					\

	do {								\

		local_trylock_t *tl;					\
@@ -285,4 +288,8 @@ do { \ 
		__local_trylock(lock);				\

	})



/* migration must be disabled before calling __local_lock_is_locked */

#define __local_lock_is_locked(__lock)					\

	(rt_mutex_owner(&this_cpu_ptr(__lock)->lock) == current)



#endif /* CONFIG_PREEMPT_RT */

include/linux/rtmutex.h

+10 −0
Original line number Diff line number Diff line
@@ -44,6 +44,16 @@ static inline bool rt_mutex_base_is_locked(struct rt_mutex_base *lock) 
	return READ_ONCE(lock->owner) != NULL;

}



#ifdef CONFIG_RT_MUTEXES

#define RT_MUTEX_HAS_WAITERS	1UL



static inline struct task_struct *rt_mutex_owner(struct rt_mutex_base *lock)

{

	unsigned long owner = (unsigned long) READ_ONCE(lock->owner);



	return (struct task_struct *) (owner & ~RT_MUTEX_HAS_WAITERS);

}

#endif

extern void rt_mutex_base_init(struct rt_mutex_base *rtb);



/**

kernel/locking/rtmutex_common.h

+0 −9
Original line number Diff line number Diff line
@@ -153,15 +153,6 @@ static inline struct rt_mutex_waiter *task_top_pi_waiter(struct task_struct *p) 
			pi_tree.entry);

}



#define RT_MUTEX_HAS_WAITERS	1UL



static inline struct task_struct *rt_mutex_owner(struct rt_mutex_base *lock)

{

	unsigned long owner = (unsigned long) READ_ONCE(lock->owner);



	return (struct task_struct *) (owner & ~RT_MUTEX_HAS_WAITERS);

}



/*

 * Constants for rt mutex functions which have a selectable deadlock

 * detection.