Subject: Re: [PATCH v2 11/16] bitfield: Common up validation of the mask parameter

From: David Laight <[email-masked]>
Date: Sun, 14 Dec 2025 13:17:40 +0000

On Sun, 14 Dec 2025 14:19:30 +0800
kernel test robot <[email-masked]> wrote:

> Hi,
> 
> kernel test robot noticed the following build errors:
> 
> [auto build test ERROR on linus/master]
> [also build test ERROR on v6.19-rc1 next-20251212]
> [cannot apply to westeri-thunderbolt/next]
> [If your patch is applied to the wrong git tree, kindly drop us a note.
> And when submitting patch, we suggest to use '--base' as documented in
> https://git-scm.com/docs/git-format-patch#_base_tree_information]
> 
> url:    https://github.com/intel-lab-lkp/linux/commits/david-laight-linux-gmail-com/nfp-Call-FIELD_PREP-in-NFP_ETH_SET_BIT_CONFIG-wrapper/20251213-040625
> base:   linus/master
> patch link:    https://lore.kernel.org/r/20251212193721.740055-12-david.laight.linux%40gmail.com
> patch subject: [PATCH v2 11/16] bitfield: Common up validation of the mask parameter
> config: i386-randconfig-053-20251213 (https://download.01.org/0day-ci/archive/20251214/[email-masked]/config)
> compiler: clang version 20.1.8 (https://github.com/llvm/llvm-project 87f0227cb60147a26a1eeb4fb06e3b505e9c7261)
> reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251214/[email-masked]/reproduce)
> 
> If you fix the issue in a separate patch/commit (i.e. not just a new version of
> the same patch/commit), kindly add following tags
> | Reported-by: kernel test robot <[email-masked]>
> | Closes: https://lore.kernel.org/oe-kbuild-all/[email-masked]/
> 
> All errors (new ones prefixed by >>):
> 
> >> drivers/gpu/drm/xe/xe_guc.c:639:19: error: converting the result of '<<' to a boolean always evaluates to true [-Werror,-Wtautological-constant-compare]  
>      639 |                 klvs[count++] = PREP_GUC_KLV_TAG(OPT_IN_FEATURE_EXT_CAT_ERR_TYPE);
>          |                                 ^
>    drivers/gpu/drm/xe/xe_guc_klv_helpers.h:62:2: note: expanded from macro 'PREP_GUC_KLV_TAG'
>       62 |         PREP_GUC_KLV_CONST(MAKE_GUC_KLV_KEY(TAG), MAKE_GUC_KLV_LEN(TAG))
>          |         ^
>    drivers/gpu/drm/xe/xe_guc_klv_helpers.h:38:20: note: expanded from macro 'PREP_GUC_KLV_CONST'
>       38 |         (FIELD_PREP_CONST(GUC_KLV_0_KEY, (key)) | \
>          |                           ^
>    drivers/gpu/drm/xe/abi/guc_klvs_abi.h:36:35: note: expanded from macro 'GUC_KLV_0_KEY'
>       36 | #define GUC_KLV_0_KEY                           (0xffffu << 16)
>          |                                                          ^

I've just sent a patch to move that warning to W=2.
It is picking up the same sort of things that -Wtype-limits does - already in W=2.

	David