[PATCH RFC 15/13] gpio: virtio: reorder fields to reduce struct padding

[Michael S. Tsirkin]

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=128:
- request is 8 bytes
- response is 2 bytes
- removing _end saves up to 128-6=122 bytes padding to align rxlen field

Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
---
 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;
 
+	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;
 };
 
 struct vgpio_irq_line {
-- 
MST