Re: [PATCH v4 bpf-next 2/3] bpf: Introduce task_vma open-coded iterator kfuncs

[kernel test robot <lkp@intel.com>]

Hi Dave,

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/Dave-Marchevsky/bpf-Don-t-explicitly-emit-BTF-for-struct-btf_iter_num/20231003-035600
base:   https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git master
patch link:    https://lore.kernel.org/r/20231002195341.2940874-3-davemarchevsky%40fb.com
patch subject: [PATCH v4 bpf-next 2/3] bpf: Introduce task_vma open-coded iterator kfuncs
config: i386-buildonly-randconfig-001-20231003 (https://download.01.org/0day-ci/archive/20231004/202310040045.CufS8H4U-lkp@intel.com/config)
compiler: gcc-7 (Ubuntu 7.5.0-6ubuntu2) 7.5.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20231004/202310040045.CufS8H4U-lkp@intel.com/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@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202310040045.CufS8H4U-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> kernel/bpf/task_iter.c:827:17: warning: no previous declaration for 'bpf_iter_task_vma_new' [-Wmissing-declarations]
    __bpf_kfunc int bpf_iter_task_vma_new(struct bpf_iter_task_vma *it,
                    ^~~~~~~~~~~~~~~~~~~~~
>> kernel/bpf/task_iter.c:871:36: warning: no previous declaration for 'bpf_iter_task_vma_next' [-Wmissing-declarations]
    __bpf_kfunc struct vm_area_struct *bpf_iter_task_vma_next(struct bpf_iter_task_vma *it)
                                       ^~~~~~~~~~~~~~~~~~~~~~
>> kernel/bpf/task_iter.c:880:18: warning: no previous declaration for 'bpf_iter_task_vma_destroy' [-Wmissing-declarations]
    __bpf_kfunc void bpf_iter_task_vma_destroy(struct bpf_iter_task_vma *it)
                     ^~~~~~~~~~~~~~~~~~~~~~~~~


vim +/bpf_iter_task_vma_new +827 kernel/bpf/task_iter.c

   826	
 > 827	__bpf_kfunc int bpf_iter_task_vma_new(struct bpf_iter_task_vma *it,
   828					      struct task_struct *task, u64 addr)
   829	{
   830		struct bpf_iter_task_vma_kern *kit = (void *)it;
   831		bool irq_work_busy = false;
   832		int err;
   833	
   834		BUILD_BUG_ON(sizeof(struct bpf_iter_task_vma_kern) != sizeof(struct bpf_iter_task_vma));
   835		BUILD_BUG_ON(__alignof__(struct bpf_iter_task_vma_kern) != __alignof__(struct bpf_iter_task_vma));
   836	
   837		/* is_iter_reg_valid_uninit guarantees that kit hasn't been initialized
   838		 * before, so non-NULL kit->data doesn't point to previously
   839		 * bpf_mem_alloc'd bpf_iter_task_vma_kern_data
   840		 */
   841		kit->data = bpf_mem_alloc(&bpf_global_ma, sizeof(struct bpf_iter_task_vma_kern_data));
   842		if (!kit->data)
   843			return -ENOMEM;
   844	
   845		kit->data->task = get_task_struct(task);
   846		kit->data->mm = task->mm;
   847		if (!kit->data->mm) {
   848			err = -ENOENT;
   849			goto err_cleanup_iter;
   850		}
   851	
   852		/* kit->data->work == NULL is valid after bpf_mmap_unlock_get_irq_work */
   853		irq_work_busy = bpf_mmap_unlock_get_irq_work(&kit->data->work);
   854		if (irq_work_busy || !mmap_read_trylock(kit->data->mm)) {
   855			err = -EBUSY;
   856			goto err_cleanup_iter;
   857		}
   858	
   859		vma_iter_init(&kit->data->vmi, kit->data->mm, addr);
   860		return 0;
   861	
   862	err_cleanup_iter:
   863		if (kit->data->task)
   864			put_task_struct(kit->data->task);
   865		bpf_mem_free(&bpf_global_ma, kit->data);
   866		/* NULL kit->data signals failed bpf_iter_task_vma initialization */
   867		kit->data = NULL;
   868		return err;
   869	}
   870	
 > 871	__bpf_kfunc struct vm_area_struct *bpf_iter_task_vma_next(struct bpf_iter_task_vma *it)
   872	{
   873		struct bpf_iter_task_vma_kern *kit = (void *)it;
   874	
   875		if (!kit->data) /* bpf_iter_task_vma_new failed */
   876			return NULL;
   877		return vma_next(&kit->data->vmi);
   878	}
   879	
 > 880	__bpf_kfunc void bpf_iter_task_vma_destroy(struct bpf_iter_task_vma *it)
   881	{
   882		struct bpf_iter_task_vma_kern *kit = (void *)it;
   883	
   884		if (kit->data) {
   885			bpf_mmap_unlock_mm(kit->data->work, kit->data->mm);
   886			put_task_struct(kit->data->task);
   887			bpf_mem_free(&bpf_global_ma, kit->data);
   888		}
   889	}
   890	

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki