linux-kernel - Re: [PATCH v4 2/3] block: prohibit calls to bio_chain

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Message-ID: <CAHc6FU53qroW6nj_ToKrSJoMZG4xrucq=jMJhc2qMr22UAWMCw@mail.gmail.com>
Date: Mon, 1 Dec 2025 10:34:42 +0100
From: Andreas Gruenbacher <agruenba@...hat.com>
To: zhangshida <starzhangzsd@...il.com>
Cc: Johannes.Thumshirn@....com, hch@...radead.org, ming.lei@...hat.com, 
	hsiangkao@...ux.alibaba.com, csander@...estorage.com, colyli@...as.com, 
	linux-block@...r.kernel.org, linux-bcache@...r.kernel.org, 
	linux-kernel@...r.kernel.org, zhangshida@...inos.cn, 
	Christoph Hellwig <hch@....de>
Subject: Re: [PATCH v4 2/3] block: prohibit calls to bio_chain_endio

On Mon, Dec 1, 2025 at 10:05 AM zhangshida <starzhangzsd@...il.com> wrote:
> From: Shida Zhang <zhangshida@...inos.cn>
>
> Now that all potential callers of bio_chain_endio have been
> eliminated, completely prohibit any future calls to this function.
>
> Suggested-by: Ming Lei <ming.lei@...hat.com>
> Suggested-by: Andreas Gruenbacher <agruenba@...hat.com>
> Suggested-by: Christoph Hellwig <hch@...radead.org>
> Reviewed-by: Christoph Hellwig <hch@....de>
> Signed-off-by: Shida Zhang <zhangshida@...inos.cn>
> ---
>  block/bio.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/block/bio.c b/block/bio.c
> index b3a79285c27..1b5e4577f4c 100644
> --- a/block/bio.c
> +++ b/block/bio.c
> @@ -320,9 +320,13 @@ static struct bio *__bio_chain_endio(struct bio *bio)
>         return parent;
>  }
>
> +/**
> + * This function should only be used as a flag and must never be called.
> + * If execution reaches here, it indicates a serious programming error.
> + */
>  static void bio_chain_endio(struct bio *bio)
>  {
> -       bio_endio(__bio_chain_endio(bio));
> +       BUG_ON(1);

Just 'BUG()'.

>  }
>
>  /**

> --
> 2.34.1
>

Andreas