kernel/bpf/helpers.c:1993:6: warning: no previous declaration for 'bpf_rcu_read_lock'

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

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   16931859a6500d360b90aeacab3b505a3560a3ed
commit: 9bb00b2895cbfe0ad410457b605d0a72524168c1 bpf: Add kfunc bpf_rcu_read_lock/unlock()
date:   9 months ago
config: x86_64-randconfig-x012-20230816 (https://download.01.org/0day-ci/archive/20230818/202308180156.XOZHWYw5-lkp@intel.com/config)
compiler: gcc-7 (Ubuntu 7.5.0-6ubuntu2) 7.5.0
reproduce: (https://download.01.org/0day-ci/archive/20230818/202308180156.XOZHWYw5-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/202308180156.XOZHWYw5-lkp@intel.com/

All warnings (new ones prefixed by >>):

   kernel/bpf/helpers.c:1760:7: warning: no previous declaration for 'bpf_obj_new_impl' [-Wmissing-declarations]
    void *bpf_obj_new_impl(u64 local_type_id__k, void *meta__ign)
          ^~~~~~~~~~~~~~~~
   kernel/bpf/helpers.c:1774:6: warning: no previous declaration for 'bpf_obj_drop_impl' [-Wmissing-declarations]
    void bpf_obj_drop_impl(void *p__alloc, void *meta__ign)
         ^~~~~~~~~~~~~~~~~
   kernel/bpf/helpers.c:1795:6: warning: no previous declaration for 'bpf_list_push_front' [-Wmissing-declarations]
    void bpf_list_push_front(struct bpf_list_head *head, struct bpf_list_node *node)
         ^~~~~~~~~~~~~~~~~~~
   kernel/bpf/helpers.c:1800:6: warning: no previous declaration for 'bpf_list_push_back' [-Wmissing-declarations]
    void bpf_list_push_back(struct bpf_list_head *head, struct bpf_list_node *node)
         ^~~~~~~~~~~~~~~~~~
   kernel/bpf/helpers.c:1818:23: warning: no previous declaration for 'bpf_list_pop_front' [-Wmissing-declarations]
    struct bpf_list_node *bpf_list_pop_front(struct bpf_list_head *head)
                          ^~~~~~~~~~~~~~~~~~
   kernel/bpf/helpers.c:1823:23: warning: no previous declaration for 'bpf_list_pop_back' [-Wmissing-declarations]
    struct bpf_list_node *bpf_list_pop_back(struct bpf_list_head *head)
                          ^~~~~~~~~~~~~~~~~
   kernel/bpf/helpers.c:1834:21: warning: no previous declaration for 'bpf_task_acquire' [-Wmissing-declarations]
    struct task_struct *bpf_task_acquire(struct task_struct *p)
                        ^~~~~~~~~~~~~~~~
   kernel/bpf/helpers.c:1846:21: warning: no previous declaration for 'bpf_task_kptr_get' [-Wmissing-declarations]
    struct task_struct *bpf_task_kptr_get(struct task_struct **pp)
                        ^~~~~~~~~~~~~~~~~
   kernel/bpf/helpers.c:1877:6: warning: no previous declaration for 'bpf_task_release' [-Wmissing-declarations]
    void bpf_task_release(struct task_struct *p)
         ^~~~~~~~~~~~~~~~
   kernel/bpf/helpers.c:1892:16: warning: no previous declaration for 'bpf_cgroup_acquire' [-Wmissing-declarations]
    struct cgroup *bpf_cgroup_acquire(struct cgroup *cgrp)
                   ^~~~~~~~~~~~~~~~~~
   kernel/bpf/helpers.c:1904:16: warning: no previous declaration for 'bpf_cgroup_kptr_get' [-Wmissing-declarations]
    struct cgroup *bpf_cgroup_kptr_get(struct cgroup **cgrpp)
                   ^~~~~~~~~~~~~~~~~~~
   kernel/bpf/helpers.c:1936:6: warning: no previous declaration for 'bpf_cgroup_release' [-Wmissing-declarations]
    void bpf_cgroup_release(struct cgroup *cgrp)
         ^~~~~~~~~~~~~~~~~~
   kernel/bpf/helpers.c:1951:16: warning: no previous declaration for 'bpf_cgroup_ancestor' [-Wmissing-declarations]
    struct cgroup *bpf_cgroup_ancestor(struct cgroup *cgrp, int level)
                   ^~~~~~~~~~~~~~~~~~~
   kernel/bpf/helpers.c:1970:21: warning: no previous declaration for 'bpf_task_from_pid' [-Wmissing-declarations]
    struct task_struct *bpf_task_from_pid(s32 pid)
                        ^~~~~~~~~~~~~~~~~
   kernel/bpf/helpers.c:1983:7: warning: no previous declaration for 'bpf_cast_to_kern_ctx' [-Wmissing-declarations]
    void *bpf_cast_to_kern_ctx(void *obj)
          ^~~~~~~~~~~~~~~~~~~~
   kernel/bpf/helpers.c:1988:7: warning: no previous declaration for 'bpf_rdonly_cast' [-Wmissing-declarations]
    void *bpf_rdonly_cast(void *obj__ign, u32 btf_id__k)
          ^~~~~~~~~~~~~~~
>> kernel/bpf/helpers.c:1993:6: warning: no previous declaration for 'bpf_rcu_read_lock' [-Wmissing-declarations]
    void bpf_rcu_read_lock(void)
         ^~~~~~~~~~~~~~~~~
>> kernel/bpf/helpers.c:1998:6: warning: no previous declaration for 'bpf_rcu_read_unlock' [-Wmissing-declarations]
    void bpf_rcu_read_unlock(void)
         ^~~~~~~~~~~~~~~~~~~


vim +/bpf_rcu_read_lock +1993 kernel/bpf/helpers.c

  1963	
  1964	/**
  1965	 * bpf_task_from_pid - Find a struct task_struct from its pid by looking it up
  1966	 * in the root pid namespace idr. If a task is returned, it must either be
  1967	 * stored in a map, or released with bpf_task_release().
  1968	 * @pid: The pid of the task being looked up.
  1969	 */
> 1970	struct task_struct *bpf_task_from_pid(s32 pid)
  1971	{
  1972		struct task_struct *p;
  1973	
  1974		rcu_read_lock();
  1975		p = find_task_by_pid_ns(pid, &init_pid_ns);
  1976		if (p)
  1977			bpf_task_acquire(p);
  1978		rcu_read_unlock();
  1979	
  1980		return p;
  1981	}
  1982	
> 1983	void *bpf_cast_to_kern_ctx(void *obj)
  1984	{
  1985		return obj;
  1986	}
  1987	
  1988	void *bpf_rdonly_cast(void *obj__ign, u32 btf_id__k)
  1989	{
  1990		return obj__ign;
  1991	}
  1992	
> 1993	void bpf_rcu_read_lock(void)
  1994	{
  1995		rcu_read_lock();
  1996	}
  1997	
> 1998	void bpf_rcu_read_unlock(void)
  1999	{
  2000		rcu_read_unlock();
  2001	}
  2002	

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