Re: [PATCH v3 06/20] seqlock: Extend seqcount API with associated locks

[Peter Zijlstra]

On Wed, Jul 08, 2020 at 02:29:38PM +0200, Peter Zijlstra wrote:

> #define SEQCOUNT_LOCKTYPE(name, locktype, preempt, lockmember)		\
> typedef struct seqcount_##name {					\
> 	seqcount_t	seqcount;					\
> 	__SEQCOUNT_LOCKDEP(locktype *lock);				\
> } seqcount_##name##_t;							\
> 									\
> static __always_inline void						\
> seqcount_##name##_init(seqcount_##name##_t *s, locktype *l)		\
> {									\
> 	seqcount_init(&s->seqcount);					\
> 	__SEQCOUNT_LOCKDEP(s->lock = l);				\
> }									\
> 									\
> static __always_inline __seqprop_ptr_t					\
> __seqprop_##name##_ptr(seqcount_##name##_t *s)				\
> {									\
> 	return &s->seqcount;						\
> }									\
> 									\
> static __always_inline __seqprop_preempt_t				\
> __seqprop_##name##_preempt(seqcount_##name##_t *s)			\
> {									\
> 	return preempt;							\
> }									\
> 									\
> static __always_inline __seqprop_assert_t				\
> __seqprop_##name##_assert(seqcount_##name##_t *s)			\
> {									\
> 	__SEQCOUNT_LOCKDEP(lockdep_assert_held(s->lockmember));		\
> }

For PREEMPT_RT's magic thing, you can add:

static __always_inline void						\
__seqprop_##name##_lock(seqcount_##name##_t *s)				\
{									\
	if (!__SEQ_RT || !preempt)					\
		return;							\
									\
	lockbase##_lock(&s->lock);					\
	lockbase##_unlock(&s->lock);					\
}

and:

#define __rt_lock_unlock_associated_sleeping_lock(s) __seqprop(s, lock)