[PATCH] bpf: hide cgroup functions for configs without cgroups

[Arnd Bergmann <arnd@kernel.org>]

From: Arnd Bergmann <arnd@arndb.de>

When cgroups are disabled, the newly added functions don't build:

kernel/bpf/task_iter.c: In function 'bpf_iter_css_task_new':
kernel/bpf/task_iter.c:917:14: error: 'CSS_TASK_ITER_PROCS' undeclared (first use in this function)
  917 |         case CSS_TASK_ITER_PROCS | CSS_TASK_ITER_THREADED:
      |              ^~~~~~~~~~~~~~~~~~~
kernel/bpf/task_iter.c:925:60: error: invalid application of 'sizeof' to incomplete type 'struct css_task_iter'
  925 |         kit->css_it = bpf_mem_alloc(&bpf_global_ma, sizeof(struct css_task_iter));
      |                                                            ^~~~~~

Hide them in an #ifdef section.

Fixes: 9c66dc94b62ae ("bpf: Introduce css_task open-coded iterator kfuncs")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 kernel/bpf/task_iter.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/kernel/bpf/task_iter.c b/kernel/bpf/task_iter.c
index 654601dd6b493..15a184f4f954d 100644
--- a/kernel/bpf/task_iter.c
+++ b/kernel/bpf/task_iter.c
@@ -904,6 +904,7 @@ __diag_push();
 __diag_ignore_all("-Wmissing-prototypes",
 		  "Global functions as their definitions will be in vmlinux BTF");
 
+#ifdef CONFIG_CGROUPS
 __bpf_kfunc int bpf_iter_css_task_new(struct bpf_iter_css_task *it,
 		struct cgroup_subsys_state *css, unsigned int flags)
 {
@@ -947,6 +948,7 @@ __bpf_kfunc void bpf_iter_css_task_destroy(struct bpf_iter_css_task *it)
 	css_task_iter_end(kit->css_it);
 	bpf_mem_free(&bpf_global_ma, kit->css_it);
 }
+#endif
 
 __diag_pop();
 
-- 
2.39.2