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SubjectRe: [PATCH 6/9] platform: goldfish: pipe: Fail compilation if structs are too large
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On Mon, 2018-08-13 at 16:38 -0700, rkir@google.com wrote:
> From: Roman Kiryanov <rkir@google.com>
>
> Since the driver provides no workaround prevent in cases if structs do
> no fit into a memory page, it is better to fail complation to find about
> the issue earlt instead of returning errors at runtime.

Minor earlt/early typo

> diff --git a/drivers/platform/goldfish/goldfish_pipe.c b/drivers/platform/goldfish/goldfish_pipe.c
[]
> @@ -797,9 +798,7 @@ static int goldfish_pipe_device_init(struct platform_device *pdev)
> * needs to be contained in a single physical page. The easiest choice
> * is to just allocate a page and place the buffers in it.
> */
> - if (WARN_ON(sizeof(*dev->buffers) > PAGE_SIZE))
> - return -ENOMEM;
> -
> + BUILD_BUG_ON(sizeof(*dev->buffers) > PAGE_SIZE);
> page = (char *)__get_free_page(GFP_KERNEL);
> if (!page) {
> kfree(dev->pipes);
> @@ -842,8 +841,7 @@ static int goldfish_pipe_probe(struct platform_device *pdev)
> struct resource *r;
> struct goldfish_pipe_dev *dev = pipe_dev;
>
> - if (WARN_ON(sizeof(struct goldfish_pipe_command) > PAGE_SIZE))
> - return -ENOMEM;
> + BUILD_BUG_ON(sizeof(struct goldfish_pipe_command) > PAGE_SIZE);
>
> /* not thread safe, but this should not happen */
> WARN_ON(dev->base != NULL);

Why separate these BUILD_BUG_ONs into 2 different functions?

Why not just
BUILD_BUG_ON(sizeof(struct goldfish_pipe_command) > PAGE_SIZE);
BUILD_BUG_ON(sizeof(struct goldfish_pipe_dev_buffers) > PAGE_SIZE);

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