bpf: Add CGROUP prefix to cgroup_iter_order

bpf_cgroup_iter_order is globally visible but the entries do not have
CGROUP prefix. As requested by Andrii, put a CGROUP in the names
in bpf_cgroup_iter_order.

This patch fixes two previous commits: one introduced the API and
the other uses the API in bpf selftest (that is, the selftest
cgroup_hierarchical_stats).

I tested this patch via the following command:

  test_progs -t cgroup,iter,btf_dump

Fixes: d4ccaf58 ("bpf: Introduce cgroup iter")
Fixes: 88886309 ("selftests/bpf: add a selftest for cgroup hierarchical stats collection")
Suggested-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Hao Luo <haoluo@google.com>
Link: https://lore.kernel.org/r/20220825223936.1865810-1-haoluo@google.comSigned-off-by: Martin KaFai Lau <kafai@fb.com>

include/uapi/linux/bpf.h

@@ -88,11 +88,11 @@ struct bpf_cgroup_storage_key {
 };
 
 enum bpf_cgroup_iter_order {
-	BPF_ITER_ORDER_UNSPEC = 0,
-	BPF_ITER_SELF_ONLY,		/* process only a single object. */
-	BPF_ITER_DESCENDANTS_PRE,	/* walk descendants in pre-order. */
-	BPF_ITER_DESCENDANTS_POST,	/* walk descendants in post-order. */
-	BPF_ITER_ANCESTORS_UP,		/* walk ancestors upward. */
+	BPF_CGROUP_ITER_ORDER_UNSPEC = 0,
+	BPF_CGROUP_ITER_SELF_ONLY,		/* process only a single object. */
+	BPF_CGROUP_ITER_DESCENDANTS_PRE,	/* walk descendants in pre-order. */
+	BPF_CGROUP_ITER_DESCENDANTS_POST,	/* walk descendants in post-order. */
+	BPF_CGROUP_ITER_ANCESTORS_UP,		/* walk ancestors upward. */
 };
 
 union bpf_iter_link_info {

kernel/bpf/cgroup_iter.c

@@ -74,13 +74,13 @@ static void *cgroup_iter_seq_start(struct seq_file *seq, loff_t *pos)
 	++*pos;
 	p->terminate = false;
 	p->visited_all = false;
-	if (p->order == BPF_ITER_DESCENDANTS_PRE)
+	if (p->order == BPF_CGROUP_ITER_DESCENDANTS_PRE)
 		return css_next_descendant_pre(NULL, p->start_css);
-	else if (p->order == BPF_ITER_DESCENDANTS_POST)
+	else if (p->order == BPF_CGROUP_ITER_DESCENDANTS_POST)
 		return css_next_descendant_post(NULL, p->start_css);
-	else if (p->order == BPF_ITER_ANCESTORS_UP)
+	else if (p->order == BPF_CGROUP_ITER_ANCESTORS_UP)
 		return p->start_css;
-	else /* BPF_ITER_SELF_ONLY */
+	else /* BPF_CGROUP_ITER_SELF_ONLY */
 		return p->start_css;
 }
 
@@ -109,13 +109,13 @@ static void *cgroup_iter_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 	if (p->terminate)
 		return NULL;
 
-	if (p->order == BPF_ITER_DESCENDANTS_PRE)
+	if (p->order == BPF_CGROUP_ITER_DESCENDANTS_PRE)
 		return css_next_descendant_pre(curr, p->start_css);
-	else if (p->order == BPF_ITER_DESCENDANTS_POST)
+	else if (p->order == BPF_CGROUP_ITER_DESCENDANTS_POST)
 		return css_next_descendant_post(curr, p->start_css);
-	else if (p->order == BPF_ITER_ANCESTORS_UP)
+	else if (p->order == BPF_CGROUP_ITER_ANCESTORS_UP)
 		return curr->parent;
-	else  /* BPF_ITER_SELF_ONLY */
+	else  /* BPF_CGROUP_ITER_SELF_ONLY */
 		return NULL;
 }
 
@@ -188,10 +188,10 @@ static int bpf_iter_attach_cgroup(struct bpf_prog *prog,
 	int order = linfo->cgroup.order;
 	struct cgroup *cgrp;
 
-	if (order != BPF_ITER_DESCENDANTS_PRE &&
-	    order != BPF_ITER_DESCENDANTS_POST &&
-	    order != BPF_ITER_ANCESTORS_UP &&
-	    order != BPF_ITER_SELF_ONLY)
+	if (order != BPF_CGROUP_ITER_DESCENDANTS_PRE &&
+	    order != BPF_CGROUP_ITER_DESCENDANTS_POST &&
+	    order != BPF_CGROUP_ITER_ANCESTORS_UP &&
+	    order != BPF_CGROUP_ITER_SELF_ONLY)
 		return -EINVAL;
 
 	if (fd && id)
@@ -239,13 +239,13 @@ static void bpf_iter_cgroup_show_fdinfo(const struct bpf_iter_aux_info *aux,
 	kfree(buf);
 
 show_order:
-	if (aux->cgroup.order == BPF_ITER_DESCENDANTS_PRE)
+	if (aux->cgroup.order == BPF_CGROUP_ITER_DESCENDANTS_PRE)
 		seq_puts(seq, "order: descendants_pre\n");
-	else if (aux->cgroup.order == BPF_ITER_DESCENDANTS_POST)
+	else if (aux->cgroup.order == BPF_CGROUP_ITER_DESCENDANTS_POST)
 		seq_puts(seq, "order: descendants_post\n");
-	else if (aux->cgroup.order == BPF_ITER_ANCESTORS_UP)
+	else if (aux->cgroup.order == BPF_CGROUP_ITER_ANCESTORS_UP)
 		seq_puts(seq, "order: ancestors_up\n");
-	else /* BPF_ITER_SELF_ONLY */
+	else /* BPF_CGROUP_ITER_SELF_ONLY */
 		seq_puts(seq, "order: self_only\n");
 }
 

tools/include/uapi/linux/bpf.h

@@ -88,11 +88,11 @@ struct bpf_cgroup_storage_key {
 };
 
 enum bpf_cgroup_iter_order {
-	BPF_ITER_ORDER_UNSPEC = 0,
-	BPF_ITER_SELF_ONLY,		/* process only a single object. */
-	BPF_ITER_DESCENDANTS_PRE,	/* walk descendants in pre-order. */
-	BPF_ITER_DESCENDANTS_POST,	/* walk descendants in post-order. */
-	BPF_ITER_ANCESTORS_UP,		/* walk ancestors upward. */
+	BPF_CGROUP_ITER_ORDER_UNSPEC = 0,
+	BPF_CGROUP_ITER_SELF_ONLY,		/* process only a single object. */
+	BPF_CGROUP_ITER_DESCENDANTS_PRE,	/* walk descendants in pre-order. */
+	BPF_CGROUP_ITER_DESCENDANTS_POST,	/* walk descendants in post-order. */
+	BPF_CGROUP_ITER_ANCESTORS_UP,		/* walk ancestors upward. */
 };
 
 union bpf_iter_link_info {

tools/testing/selftests/bpf/prog_tests/btf_dump.c

@@ -764,7 +764,7 @@ static void test_btf_dump_struct_data(struct btf *btf, struct btf_dump *d,
 
 	/* union with nested struct */
 	TEST_BTF_DUMP_DATA(btf, d, "union", str, union bpf_iter_link_info, BTF_F_COMPACT,
-			   "(union bpf_iter_link_info){.map = (struct){.map_fd = (__u32)1,},.cgroup = (struct){.order = (enum bpf_cgroup_iter_order)BPF_ITER_SELF_ONLY,.cgroup_fd = (__u32)1,},}",
+			   "(union bpf_iter_link_info){.map = (struct){.map_fd = (__u32)1,},.cgroup = (struct){.order = (enum bpf_cgroup_iter_order)BPF_CGROUP_ITER_SELF_ONLY,.cgroup_fd = (__u32)1,},}",
 			   { .cgroup = { .order = 1, .cgroup_fd = 1, }});
 
 	/* struct skb with nested structs/unions; because type output is so

tools/testing/selftests/bpf/prog_tests/cgroup_hierarchical_stats.c

@@ -275,7 +275,7 @@ static int setup_cgroup_iter(struct cgroup_hierarchical_stats *obj,
 	 * traverse one cgroup, so set the traversal order to "self".
 	 */
 	linfo.cgroup.cgroup_fd = cgroup_fd;
-	linfo.cgroup.order = BPF_ITER_SELF_ONLY;
+	linfo.cgroup.order = BPF_CGROUP_ITER_SELF_ONLY;
 	opts.link_info = &linfo;
 	opts.link_info_len = sizeof(linfo);
 	link = bpf_program__attach_iter(obj->progs.dump_vmscan, &opts);

tools/testing/selftests/bpf/prog_tests/cgroup_iter.c

@@ -134,7 +134,7 @@ static void test_walk_preorder(struct cgroup_iter *skel)
 		 cg_id[PARENT], cg_id[CHILD1], cg_id[CHILD2]);
 
 	read_from_cgroup_iter(skel->progs.cgroup_id_printer, cg_fd[PARENT],
-			      BPF_ITER_DESCENDANTS_PRE, "preorder");
+			      BPF_CGROUP_ITER_DESCENDANTS_PRE, "preorder");
 }
 
 /* Postorder walk prints child and parent in order. */
@@ -145,7 +145,7 @@ static void test_walk_postorder(struct cgroup_iter *skel)
 		 cg_id[CHILD1], cg_id[CHILD2], cg_id[PARENT]);
 
 	read_from_cgroup_iter(skel->progs.cgroup_id_printer, cg_fd[PARENT],
-			      BPF_ITER_DESCENDANTS_POST, "postorder");
+			      BPF_CGROUP_ITER_DESCENDANTS_POST, "postorder");
 }
 
 /* Walking parents prints parent and then root. */
@@ -159,7 +159,7 @@ static void test_walk_ancestors_up(struct cgroup_iter *skel)
 		 cg_id[PARENT], cg_id[ROOT]);
 
 	read_from_cgroup_iter(skel->progs.cgroup_id_printer, cg_fd[PARENT],
-			      BPF_ITER_ANCESTORS_UP, "ancestors_up");
+			      BPF_CGROUP_ITER_ANCESTORS_UP, "ancestors_up");
 
 	skel->bss->terminal_cgroup = 0;
 }
@@ -174,7 +174,7 @@ static void test_early_termination(struct cgroup_iter *skel)
 		 PROLOGUE "%8llu\n" EPILOGUE, cg_id[PARENT]);
 
 	read_from_cgroup_iter(skel->progs.cgroup_id_printer, cg_fd[PARENT],
-			      BPF_ITER_DESCENDANTS_PRE, "early_termination");
+			      BPF_CGROUP_ITER_DESCENDANTS_PRE, "early_termination");
 
 	skel->bss->terminate_early = 0;
 }
@@ -186,7 +186,7 @@ static void test_walk_self_only(struct cgroup_iter *skel)
 		 PROLOGUE "%8llu\n" EPILOGUE, cg_id[PARENT]);
 
 	read_from_cgroup_iter(skel->progs.cgroup_id_printer, cg_fd[PARENT],
-			      BPF_ITER_SELF_ONLY, "self_only");
+			      BPF_CGROUP_ITER_SELF_ONLY, "self_only");
 }
 
 void test_cgroup_iter(void)