linux-kernel - Re: [PATCH v2 2/5] vduse: Use memcpy_{to,from}_page() in do

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Date:   Wed, 13 Jul 2022 13:59:17 +0800
From:   Jason Wang <jasowang@...hat.com>
To:     Xie Yongji <xieyongji@...edance.com>, mst@...hat.com,
        xiaodong.liu@...el.com, maxime.coquelin@...hat.com,
        stefanha@...hat.com
Cc:     songmuchun@...edance.com,
        virtualization@...ts.linux-foundation.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 2/5] vduse: Use memcpy_{to,from}_page() in do_bounce()


在 2022/7/6 13:05, Xie Yongji 写道:
> kmap_atomic() is being deprecated in favor of kmap_local_page().
>
> The use of kmap_atomic() in do_bounce() is all thread local therefore
> kmap_local_page() is a sufficient replacement.
>
> Convert to kmap_local_page() but, instead of open coding it,
> use the helpers memcpy_to_page() and memcpy_from_page().
>
> Signed-off-by: Xie Yongji <xieyongji@...edance.com>


Acked-by: Jason Wang <jasowang@...hat.com>


> ---
>   drivers/vdpa/vdpa_user/iova_domain.c | 9 ++++-----
>   1 file changed, 4 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/vdpa/vdpa_user/iova_domain.c b/drivers/vdpa/vdpa_user/iova_domain.c
> index bca1f0b8850c..50d7c08d5450 100644
> --- a/drivers/vdpa/vdpa_user/iova_domain.c
> +++ b/drivers/vdpa/vdpa_user/iova_domain.c
> @@ -138,18 +138,17 @@ static void do_bounce(phys_addr_t orig, void *addr, size_t size,
>   {
>   	unsigned long pfn = PFN_DOWN(orig);
>   	unsigned int offset = offset_in_page(orig);
> -	char *buffer;
> +	struct page *page;
>   	unsigned int sz = 0;
>   
>   	while (size) {
>   		sz = min_t(size_t, PAGE_SIZE - offset, size);
>   
> -		buffer = kmap_atomic(pfn_to_page(pfn));
> +		page = pfn_to_page(pfn);
>   		if (dir == DMA_TO_DEVICE)
> -			memcpy(addr, buffer + offset, sz);
> +			memcpy_from_page(addr, page, offset, sz);
>   		else
> -			memcpy(buffer + offset, addr, sz);
> -		kunmap_atomic(buffer);
> +			memcpy_to_page(page, offset, addr, sz);
>   
>   		size -= sz;
>   		pfn++;