linux-kernel - Re: [RFC for-next v2 3/4] block/bio: add pcpu caching for non-polling bio

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Date:   Thu, 20 Oct 2022 01:31:43 -0700
From:   Christoph Hellwig <hch@...radead.org>
To:     Pavel Begunkov <asml.silence@...il.com>
Cc:     Jens Axboe <axboe@...nel.dk>, linux-block@...r.kernel.org,
        io-uring@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-fsdevel@...r.kernel.org
Subject: Re: [RFC for-next v2 3/4] block/bio: add pcpu caching for
 non-polling bio_put

> +	unsigned long flags;
>  
>  	cache = per_cpu_ptr(bio->bi_pool->cache, get_cpu());
>  	bio_uninit(bio);
> @@ -737,12 +776,15 @@ static inline void bio_put_percpu_cache(struct bio *bio)
>  		cache->free_list = bio;
>  		cache->nr++;
>  	} else {
> -		put_cpu();
> -		bio_free(bio);
> -		return;
> +		local_irq_save(flags);
> +		bio->bi_next = cache->free_list_irq;
> +		cache->free_list_irq = bio;
> +		cache->nr_irq++;
> +		local_irq_restore(flags);
>  	}

Ok, I guess with that my previous comments don't make quite
as much sense any more.  I think youcan keep flags local in
the branch here, though.