include/linux/rwbase_rt.h

// SPDX-License-Identifier: GPL-2.0-only
#ifndef _LINUX_RWBASE_RT_H
#define _LINUX_RWBASE_RT_H

#include <linux/rtmutex.h>
#include <linux/atomic.h>

#define READER_BIAS		(1U << 31)
#define WRITER_BIAS		(1U << 30)

struct rwbase_rt {
	atomic_t		readers;
	struct rt_mutex_base	rtmutex;
};

#define __RWBASE_INITIALIZER(name)				\
{								\
	.readers = ATOMIC_INIT(READER_BIAS),			\
	.rtmutex = __RT_MUTEX_BASE_INITIALIZER(name.rtmutex),	\
}

#define init_rwbase_rt(rwbase)					\
	do {							\
		rt_mutex_base_init(&(rwbase)->rtmutex);		\
		atomic_set(&(rwbase)->readers, READER_BIAS);	\
	} while (0)


static __always_inline bool rw_base_is_locked(const struct rwbase_rt *rwb)
{
	return atomic_read(&rwb->readers) != READER_BIAS;
}

static inline void rw_base_assert_held_write(const struct rwbase_rt *rwb)
{
	WARN_ON(atomic_read(&rwb->readers) != WRITER_BIAS);
}

static __always_inline bool rw_base_is_contended(const struct rwbase_rt *rwb)
{
	return atomic_read(&rwb->readers) > 0;
}

#endif /* _LINUX_RWBASE_RT_H */