#ifndef __LINUX_SEQLOCK_H
#define __LINUX_SEQLOCK_H

#include <linux/spinlock.h>
#include <pthread.h>
#include <linux/types.h>

extern _Bool __VERIFIER_nondet_bool(void);
extern char __VERIFIER_nondet_char(void);
extern uint __VERIFIER_nondet_uint(void);
extern int __VERIFIER_nondet_int(void);
extern ulong __VERIFIER_nondet_ulong(void);
extern long __VERIFIER_nondet_long(void);

extern void __VERIFIER_atomic_begin(void);

extern void __VERIFIER_atomic_end(void);

extern void abort(void); 
#include <assert.h>
void reach_error() { assert(0); }

extern void abort(void); 
void assume_abort_if_not(int cond) { 
  if(!cond) {abort();}
}

void __VERIFIER_assert(int cond) {
  if (!(cond)) {
    ERROR: {reach_error();abort();}
  }
  return;
}

/*
 * Version using sequence counter only.
 * This can be used when code has its own mutex protecting the
 * updating starting before the write_seqcountbeqin() and ending
 * after the write_seqcount_end().
 */
typedef struct seqcount {
	unsigned sequence;
} seqcount_t;

#define SEQCNT_ZERO { 0 }
#define seqcount_init(x)	do { *(x) = (seqcount_t) SEQCNT_ZERO; } while (0)

extern void cpu_relax(void);
extern void smp_rmb(void);

/**
 * __read_seqcount_begin - begin a seq-read critical section (without barrier)
 * @s: pointer to seqcount_t
 * Returns: count to be passed to read_seqcount_retry
 *
 * __read_seqcount_begin is like read_seqcount_begin, but has no smp_rmb()
 * barrier. Callers should ensure that smp_rmb() or equivalent ordering is
 * provided before actually loading any of the variables that are to be
 * protected in this critical section.
 *
 * Use carefully, only in critical code, and comment how the barrier is
 * provided.
 */
static inline unsigned __read_seqcount_begin(const seqcount_t *s)
{
	unsigned ret;

repeat:
	ret = s->sequence;
	if (ret & 1) {
		cpu_relax();
		goto repeat;
	}
	return ret;
}

/**
 * read_seqcount_begin - begin a seq-read critical section
 * @s: pointer to seqcount_t
 * Returns: count to be passed to read_seqcount_retry
 *
 * read_seqcount_begin opens a read critical section of the given seqcount.
 * Validity of the critical section is tested by checking read_seqcount_retry
 * function.
 */
static inline unsigned read_seqcount_begin(const seqcount_t *s)
{
	unsigned ret = __read_seqcount_begin(s);
	smp_rmb();
	return ret;
}

/**
 * raw_seqcount_begin - begin a seq-read critical section
 * @s: pointer to seqcount_t
 * Returns: count to be passed to read_seqcount_retry
 *
 * raw_seqcount_begin opens a read critical section of the given seqcount.
 * Validity of the critical section is tested by checking read_seqcount_retry
 * function.
 *
 * Unlike read_seqcount_begin(), this function will not wait for the count
 * to stabilize. If a writer is active when we begin, we will fail the
 * read_seqcount_retry() instead of stabilizing at the beginning of the
 * critical section.
 */
static inline unsigned raw_seqcount_begin(const seqcount_t *s)
{
	unsigned ret = s->sequence;
	smp_rmb();
	return ret & ~1;
}

/**
 * __read_seqcount_retry - end a seq-read critical section (without barrier)
 * @s: pointer to seqcount_t
 * @start: count, from read_seqcount_begin
 * Returns: 1 if retry is required, else 0
 *
 * __read_seqcount_retry is like read_seqcount_retry, but has no smp_rmb()
 * barrier. Callers should ensure that smp_rmb() or equivalent ordering is
 * provided before actually loading any of the variables that are to be
 * protected in this critical section.
 *
 * Use carefully, only in critical code, and comment how the barrier is
 * provided.
 */
static inline int __read_seqcount_retry(const seqcount_t *s, unsigned start)
{
	return s->sequence != start;
}

/**
 * read_seqcount_retry - end a seq-read critical section
 * @s: pointer to seqcount_t
 * @start: count, from read_seqcount_begin
 * Returns: 1 if retry is required, else 0
 *
 * read_seqcount_retry closes a read critical section of the given seqcount.
 * If the critical section was invalid, it must be ignored (and typically
 * retried).
 */
static inline int read_seqcount_retry(const seqcount_t *s, unsigned start)
{
	smp_rmb();
	return __read_seqcount_retry(s, start);
}


/*
 * Sequence counter only version assumes that callers are using their
 * own mutexing.
 */
static inline void write_seqcount_begin(seqcount_t *s)
{
	s->sequence++;
}

static inline void write_seqcount_end(seqcount_t *s)
{
	s->sequence++;
}

/**
 * write_seqcount_barrier - invalidate in-progress read-side seq operations
 * @s: pointer to seqcount_t
 *
 * After write_seqcount_barrier, no read-side seq operations will complete
 * successfully and see data older than this.
 */
static inline void write_seqcount_barrier(seqcount_t *s)
{
	s->sequence+=2;
}

typedef struct {
	struct seqcount seqcount;
	spinlock_t lock;
} seqlock_t;

/*
 * These macros triggered gcc-3.x compile-time problems.  We think these are
 * OK now.  Be cautious.
 */
#define __SEQLOCK_UNLOCKED(lockname)			\
	{						\
		.seqcount = SEQCNT_ZERO,		\
		.lock =	__SPIN_LOCK_UNLOCKED(lockname)	\
	}

#define seqlock_init(x)					\
	do {						\
		seqcount_init(&(x)->seqcount);		\
		spin_lock_init(&(x)->lock);		\
	} while (0)

#define DEFINE_SEQLOCK(x) \
		seqlock_t x = __SEQLOCK_UNLOCKED(x)

/*
 * Read side functions for starting and finalizing a read side section.
 */
static inline unsigned read_seqbegin(const seqlock_t *sl)
{
	return read_seqcount_begin(&sl->seqcount);
}

static inline unsigned read_seqretry(const seqlock_t *sl, unsigned start)
{
	return read_seqcount_retry(&sl->seqcount, start);
}

/*
 * Lock out other writers and update the count.
 * Acts like a normal spin_lock/unlock.
 * Don't need preempt_disable() because that is in the spin_lock already.
 */
static inline void write_seqlock(seqlock_t *sl)
{
	spin_lock(&sl->lock);
	write_seqcount_begin(&sl->seqcount);
}

static inline void write_sequnlock(seqlock_t *sl)
{
	write_seqcount_end(&sl->seqcount);
	spin_unlock(&sl->lock);
}

static inline void write_seqlock_bh(seqlock_t *sl)
{
	spin_lock_bh(&sl->lock);
	write_seqcount_begin(&sl->seqcount);
}

static inline void write_sequnlock_bh(seqlock_t *sl)
{
	write_seqcount_end(&sl->seqcount);
	spin_unlock_bh(&sl->lock);
}

static inline void write_seqlock_irq(seqlock_t *sl)
{
	spin_lock_irq(&sl->lock);
	write_seqcount_begin(&sl->seqcount);
}

static inline void write_sequnlock_irq(seqlock_t *sl)
{
	write_seqcount_end(&sl->seqcount);
	spin_unlock_irq(&sl->lock);
}

static inline unsigned long __write_seqlock_irqsave(seqlock_t *sl)
{
	unsigned long flags = __VERIFIER_nondet_ulong();

	spin_lock_irqsave(&sl->lock, flags);
	write_seqcount_begin(&sl->seqcount);
	return flags;
}

#define write_seqlock_irqsave(lock, flags)				\
	do { flags = __write_seqlock_irqsave(lock); } while (0)

static inline void
write_sequnlock_irqrestore(seqlock_t *sl, unsigned long flags)
{
	write_seqcount_end(&sl->seqcount);
	spin_unlock_irqrestore(&sl->lock, flags);
}

/*
 * A locking reader exclusively locks out other writers and locking readers,
 * but doesn't update the sequence number. Acts like a normal spin_lock/unlock.
 * Don't need preempt_disable() because that is in the spin_lock already.
 */
static inline void read_seqlock_excl(seqlock_t *sl)
{
	spin_lock(&sl->lock);
}

static inline void read_sequnlock_excl(seqlock_t *sl)
{
	spin_unlock(&sl->lock);
}

static inline void read_seqlock_excl_bh(seqlock_t *sl)
{
	spin_lock_bh(&sl->lock);
}

static inline void read_sequnlock_excl_bh(seqlock_t *sl)
{
	spin_unlock_bh(&sl->lock);
}

static inline void read_seqlock_excl_irq(seqlock_t *sl)
{
	spin_lock_irq(&sl->lock);
}

static inline void read_sequnlock_excl_irq(seqlock_t *sl)
{
	spin_unlock_irq(&sl->lock);
}

static inline unsigned long __read_seqlock_excl_irqsave(seqlock_t *sl)
{
	unsigned long flags = __VERIFIER_nondet_ulong();

	spin_lock_irqsave(&sl->lock, flags);
	return flags;
}

#define read_seqlock_excl_irqsave(lock, flags)				\
	do { flags = __read_seqlock_excl_irqsave(lock); } while (0)

static inline void
read_sequnlock_excl_irqrestore(seqlock_t *sl, unsigned long flags)
{
	spin_unlock_irqrestore(&sl->lock, flags);
}

#endif /* __LINUX_SEQLOCK_H */
