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[80.230.31.118]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-4324ea1af2bsm69151255f8f.1.2025.12.30.08.40.33 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 30 Dec 2025 08:40:36 -0800 (PST) Date: Tue, 30 Dec 2025 11:40:33 -0500 From: "Michael S. Tsirkin" To: linux-kernel@vger.kernel.org Cc: Cong Wang , Jonathan Corbet , Olivia Mackall , Herbert Xu , Jason Wang , Paolo Bonzini , Stefan Hajnoczi , Eugenio =?utf-8?B?UMOpcmV6?= , "James E.J. Bottomley" , "Martin K. Petersen" , Gerd Hoffmann , Xuan Zhuo , Marek Szyprowski , Robin Murphy , Stefano Garzarella , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , Petr Tesarik , Leon Romanovsky , Jason Gunthorpe , linux-doc@vger.kernel.org, linux-crypto@vger.kernel.org, virtualization@lists.linux.dev, linux-scsi@vger.kernel.org, iommu@lists.linux.dev, kvm@vger.kernel.org, netdev@vger.kernel.org, "Enrico Weigelt, metux IT consult" , Viresh Kumar , Linus Walleij , Bartosz Golaszewski , linux-gpio@vger.kernel.org Subject: [PATCH RFC 15/13] gpio: virtio: reorder fields to reduce struct padding Message-ID: <55e9351282f530e2302e11497c6339c4a2e74471.1767112757.git.mst@redhat.com> References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-Mailer: git-send-email 2.27.0.106.g8ac3dc51b1 X-Mutt-Fcc: =sent Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Reorder struct virtio_gpio_line fields to place the DMA buffers (req/res) last. This eliminates the need for __dma_from_device_aligned_end padding after the DMA buffer, since struct tail padding naturally protects it, making the struct a bit smaller. Size reduction estimation when ARCH_DMA_MINALIGN=3D128: - request is 8 bytes - response is 2 bytes - removing _end saves up to 128-6=3D122 bytes padding to align rxlen field Signed-off-by: Michael S. Tsirkin Acked-by: Bartosz Golaszewski Acked-by: Viresh Kumar --- drivers/gpio/gpio-virtio.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/drivers/gpio/gpio-virtio.c b/drivers/gpio/gpio-virtio.c index 32b578b46df8..8b30a94e4625 100644 --- a/drivers/gpio/gpio-virtio.c +++ b/drivers/gpio/gpio-virtio.c @@ -26,12 +26,11 @@ struct virtio_gpio_line { struct mutex lock; /* Protects line operation */ struct completion completion; =20 + unsigned int rxlen; + __dma_from_device_aligned_begin struct virtio_gpio_request req; struct virtio_gpio_response res; - - __dma_from_device_aligned_end - unsigned int rxlen; }; =20 struct vgpio_irq_line { --=20 MST