Re: [PATCH for-next 7/9] RDMA/rxe: Add elem->valid field

[Jason Gunthorpe <jgg@nvidia.com>]

On Fri, Jul 21, 2023 at 03:50:20PM -0500, Bob Pearson wrote:
> Currently the rxe driver stores NULL in the pool xarray to
> indicate that the pool element should not be looked up from its
> index. This prevents looping over pool elements during driver
> cleanup. This patch adds a new valid field to struct rxe_pool_elem
> as an alternative way to accomplish the same thing.

Wah? Why? Yuk.

> @@ -249,13 +252,6 @@ int __rxe_put(struct rxe_pool_elem *elem)
>  
>  void __rxe_finalize(struct rxe_pool_elem *elem, bool sleepable)
>  {
> -	gfp_t gfp_flags = sleepable ? GFP_KERNEL : GFP_ATOMIC;
> -	struct xarray *xa = &elem->pool->xa;
> -	unsigned long flags;
> -	void *xa_ret;
> -
> -	xa_lock_irqsave(xa, flags);
> -	xa_ret = __xa_store(xa, elem->index, elem, gfp_flags);
> -	xa_unlock_irqrestore(xa, flags);
> -	WARN_ON(xa_err(xa_ret));
> +	/* allow looking up element from index */
> +	smp_store_release(&elem->valid, 1);
>  }

That is horrible, why?

Jason