Message-ID: <3f2ed38f-e0ce-aa59-88a3-c2cfbb2f83a4@nvidia.com>
Date:   Mon, 10 Jan 2022 17:18:53 -0800
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Subject: Re: [PATCH v2 05/28] gup: Change the calling convention for
 compound_next()
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To:     "Matthew Wilcox (Oracle)" <willy@infradead.org>, linux-mm@kvack.org
Cc:     Christoph Hellwig <hch@infradead.org>,
        William Kucharski <william.kucharski@oracle.com>,
        linux-kernel@vger.kernel.org, Jason Gunthorpe <jgg@ziepe.ca>
References: <20220110042406.499429-1-willy@infradead.org>
 <20220110042406.499429-6-willy@infradead.org>
From:   John Hubbard <jhubbard@nvidia.com>
In-Reply-To: <20220110042406.499429-6-willy@infradead.org>
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On 1/9/22 20:23, Matthew Wilcox (Oracle) wrote:
> Return the head page instead of storing it to a passed parameter.
> 
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
> ---
>   mm/gup.c | 11 +++++------
>   1 file changed, 5 insertions(+), 6 deletions(-)


Reviewed-by: John Hubbard <jhubbard@nvidia.com>


thanks,
-- 
John Hubbard
NVIDIA

> 
> diff --git a/mm/gup.c b/mm/gup.c
> index 6eedca605b3d..8a0ea220ced1 100644
> --- a/mm/gup.c
> +++ b/mm/gup.c
> @@ -245,9 +245,8 @@ static inline struct page *compound_range_next(unsigned long i,
>   	return page;
>   }
>   
> -static inline void compound_next(unsigned long i, unsigned long npages,
> -				 struct page **list, struct page **head,
> -				 unsigned int *ntails)
> +static inline struct page *compound_next(unsigned long i,
> +		unsigned long npages, struct page **list, unsigned int *ntails)
>   {
>   	struct page *page;
>   	unsigned int nr;
> @@ -258,8 +257,8 @@ static inline void compound_next(unsigned long i, unsigned long npages,
>   			break;
>   	}
>   
> -	*head = page;
>   	*ntails = nr - i;
> +	return page;
>   }
>   
>   /**
> @@ -297,7 +296,7 @@ void unpin_user_pages_dirty_lock(struct page **pages, unsigned long npages,
>   	}
>   
>   	for (index = 0; index < npages; index += ntails) {
> -		compound_next(index, npages, pages, &head, &ntails);
> +		head = compound_next(index, npages, pages, &ntails);
>   		/*
>   		 * Checking PageDirty at this point may race with
>   		 * clear_page_dirty_for_io(), but that's OK. Two key
> @@ -386,7 +385,7 @@ void unpin_user_pages(struct page **pages, unsigned long npages)
>   		return;
>   
>   	for (index = 0; index < npages; index += ntails) {
> -		compound_next(index, npages, pages, &head, &ntails);
> +		head = compound_next(index, npages, pages, &ntails);
>   		put_compound_head(head, ntails, FOLL_PIN);
>   	}
>   }