Re: [PATCH] Locking: Let PREEMPT_RT compile again with new rwsem asserts.

[Matthew Wilcox <willy@infradead.org>]

On Tue, Mar 19, 2024 at 08:05:50AM +0100, Sebastian Andrzej Siewior wrote:
> -static inline void rwsem_assert_held_write_nolockdep(const struct rw_semaphore *sem)
> +static __always_inline bool rwsem_held_write(const struct rw_semaphore *sem)

The locking maintainers were very clear that this predicate Should Not
Exist.  It encourages people to write bad code.  Assertions only!

>  {
> -	rw_base_assert_held_write(sem);
> +	return rw_base_is_write_locked(&sem->rwbase);
> +}
> +
> +static __always_inline void rwsem_assert_held_write_nolockdep(const struct rw_semaphore *sem)
> +{
> +	WARN_ON(!rwsem_held_write(sem));
>  }
>  
>  static __always_inline int rwsem_is_contended(struct rw_semaphore *sem)
> -- 
> 2.43.0
>