netdev - Re: [PATCH v2 15/15] gpio: virtio: reorder fields to reduce struct padding

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Message-ID: <CAMRc=MeTW7rTVBYBub5CL6-xSWKYOUtN7UN6cH12Or_K7PrAGQ@mail.gmail.com>
Date: Mon, 5 Jan 2026 09:49:06 +0000
From: Bartosz Golaszewski <brgl@...nel.org>
To: "Michael S. Tsirkin" <mst@...hat.com>
Cc: Cong Wang <xiyou.wangcong@...il.com>, Jonathan Corbet <corbet@....net>, 
	Olivia Mackall <olivia@...enic.com>, Herbert Xu <herbert@...dor.apana.org.au>, 
	Jason Wang <jasowang@...hat.com>, Paolo Bonzini <pbonzini@...hat.com>, 
	Stefan Hajnoczi <stefanha@...hat.com>, Eugenio Pérez <eperezma@...hat.com>, 
	"James E.J. Bottomley" <James.Bottomley@...senpartnership.com>, 
	"Martin K. Petersen" <martin.petersen@...cle.com>, Gerd Hoffmann <kraxel@...hat.com>, 
	Xuan Zhuo <xuanzhuo@...ux.alibaba.com>, Marek Szyprowski <m.szyprowski@...sung.com>, 
	Robin Murphy <robin.murphy@....com>, Stefano Garzarella <sgarzare@...hat.com>, 
	"David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, 
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, Simon Horman <horms@...nel.org>, 
	Petr Tesarik <ptesarik@...e.com>, Leon Romanovsky <leon@...nel.org>, Jason Gunthorpe <jgg@...pe.ca>, 
	Bartosz Golaszewski <brgl@...nel.org>, linux-doc@...r.kernel.org, linux-crypto@...r.kernel.org, 
	virtualization@...ts.linux.dev, linux-scsi@...r.kernel.org, 
	iommu@...ts.linux.dev, kvm@...r.kernel.org, netdev@...r.kernel.org, 
	Viresh Kumar <viresh.kumar@...aro.org>, 
	"Enrico Weigelt, metux IT consult" <info@...ux.net>, Viresh Kumar <vireshk@...nel.org>, Linus Walleij <linusw@...nel.org>, 
	linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 15/15] gpio: virtio: reorder fields to reduce struct padding

On Mon, 5 Jan 2026 09:23:49 +0100, "Michael S. Tsirkin" <mst@...hat.com> said:
> Reorder struct virtio_gpio_line fields to place the DMA buffers
> (req/res) last.
>
> This eliminates the padding from aligning struct size on
> ARCH_DMA_MINALIGN.
>
> Acked-by: Viresh Kumar <viresh.kumar@...aro.org>
> Signed-off-by: Michael S. Tsirkin <mst@...hat.com>
> ---
>  drivers/gpio/gpio-virtio.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpio/gpio-virtio.c b/drivers/gpio/gpio-virtio.c
> index b70294626770..ed6e0e90fa8a 100644
> --- a/drivers/gpio/gpio-virtio.c
> +++ b/drivers/gpio/gpio-virtio.c
> @@ -26,11 +26,12 @@ struct virtio_gpio_line {
>  	struct mutex lock; /* Protects line operation */
>  	struct completion completion;
>
> +	unsigned int rxlen;
> +
>  	__dma_from_device_group_begin();
>  	struct virtio_gpio_request req;
>  	struct virtio_gpio_response res;
>  	__dma_from_device_group_end();
> -	unsigned int rxlen;
>  };
>
>  struct vgpio_irq_line {
> --
> MST
>
>

Acked-by: Bartosz Golaszewski <bartosz.golaszewski@....qualcomm.com>