On Mon, Nov 03, 2014 at 06:34:13AM -0800, Jeff Kirsher wrote:
> From: Mark Rustad
>
> The macro __compiletime_error_fallback has an error in that it
> lacks parens around the expansion of an expression. It also
> lacks a conversion to a boolean value. The first problem can
> result in a mis-evaluation. The second problem can also result
> in an error if the value comes out negative. That would thwart
> the intended error generation. That is, the error being asserted
> would not in fact generate an error. Fix both problems by adding
> !!() to the expansion.
>
> Signed-off-by: Mark Rustad
> Tested-by: Aaron Brown
> Signed-off-by: Jeff Kirsher
Good catch.
Reviewed-by: Josh Triplett
> include/linux/compiler.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/include/linux/compiler.h b/include/linux/compiler.h
> index d5ad7b1..59dc611 100644
> --- a/include/linux/compiler.h
> +++ b/include/linux/compiler.h
> @@ -331,7 +331,7 @@ void ftrace_likely_update(struct ftrace_branch_data *f,
> int val, int expect);
> */
> # ifndef __CHECKER__
> # define __compiletime_error_fallback(condition) \
> - do { ((void)sizeof(char[1 - 2 * condition])); } while (0)
> + do { ((void)sizeof(char[1 - 2 * !!(condition)])); } while (0)
> # endif
> #endif
> #ifndef __compiletime_error_fallback
> --
> 1.9.3
>
> --
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