Re: [PATCH bpf-next v1 1/2] bpf: Add kfuncs for detecting execution context

[kernel test robot]

Hi Jiayuan,

kernel test robot noticed the following build warnings:

[auto build test WARNING on bpf-next/master]

url:    https://github.com/intel-lab-lkp/linux/commits/Jiayuan-Chen/bpf-Add-kfuncs-for-detecting-execution-context/20251022-193551
base:   https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git master
patch link:    https://lore.kernel.org/r/20251022113412.352307-2-jiayuan.chen%40linux.dev
patch subject: [PATCH bpf-next v1 1/2] bpf: Add kfuncs for detecting execution context
config: alpha-randconfig-r123-20251023 (https://download.01.org/0day-ci/archive/20251024/202510242353.hCaLzqVt-lkp@xxxxxxxxx/config)
compiler: alpha-linux-gcc (GCC) 11.5.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251024/202510242353.hCaLzqVt-lkp@xxxxxxxxx/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 <lkp@xxxxxxxxx>
| Closes: https://lore.kernel.org/oe-kbuild-all/202510242353.hCaLzqVt-lkp@xxxxxxxxx/

sparse warnings: (new ones prefixed by >>)
   kernel/bpf/helpers.c:1199:21: sparse: sparse: incorrect type in assignment (different address spaces) @@     expected unsigned long long ( *[usertype] callback_fn )( ... ) @@     got void [noderef] __rcu * @@
   kernel/bpf/helpers.c:1199:21: sparse:     expected unsigned long long ( *[usertype] callback_fn )( ... )
   kernel/bpf/helpers.c:1199:21: sparse:     got void [noderef] __rcu *
   kernel/bpf/helpers.c:2480:18: sparse: sparse: symbol 'bpf_task_release_dtor' was not declared. Should it be static?
   kernel/bpf/helpers.c:2510:18: sparse: sparse: symbol 'bpf_cgroup_release_dtor' was not declared. Should it be static?
>> kernel/bpf/helpers.c:4260:18: sparse: sparse: symbol 'bpf_in_nmi_context' was not declared. Should it be static?
   kernel/bpf/helpers.c:2976:18: sparse: sparse: context imbalance in 'bpf_rcu_read_lock' - wrong count at exit
   kernel/bpf/helpers.c:2981:18: sparse: sparse: context imbalance in 'bpf_rcu_read_unlock' - unexpected unlock

vim +/bpf_in_nmi_context +4260 kernel/bpf/helpers.c

  4254	
  4255	/**
  4256	 * bpf_in_nmi_context - Check whether we are serving NMI
  4257	 *
  4258	 * Return: true if we are serving NMI
  4259	 */
> 4260	__bpf_kfunc bool bpf_in_nmi_context(void)
  4261	{
  4262		return in_nmi();
  4263	}
  4264	

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