Re: [PATCH 7/9] infiniband: uverbs: avoid out-of-range warnings

Jason Gunthorpe
2024-04-03T15:45:36Z

On Thu, Mar 28, 2024 at 03:30:45PM +0100, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
>
> clang warns for comparisons that are always true, which is the case
> for these two page size checks on architectures with 64KB pages:
>
> drivers/infiniband/core/uverbs_ioctl.c:90:39: error: result of comparison of constant 65536 with expression of type 'u16' (aka 'unsigned short') is always false [-Werror,-Wtautological-constant-out-of-range-compare]
> WARN_ON_ONCE(method_elm->bundle_size > PAGE_SIZE);
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~
> include/asm-generic/bug.h:104:25: note: expanded from macro 'WARN_ON_ONCE'
> int __ret_warn_on = !!(condition); \
> ^~~~~~~~~
> drivers/infiniband/core/uverbs_ioctl.c:621:17: error: result of comparison of constant 65536 with expression of type '__u16' (aka 'unsigned short') is always false [-Werror,-Wtautological-constant-out-of-range-compare]
> if (hdr.length > PAGE_SIZE ||
> ~~~~~~~~~~ ^ ~~~~~~~~~
>
> Add a cast to u32 in both cases, so it never warns about this.

But doesn't that hurt the codegen?

Jason