From: Yonghong Song <yhs@fb.com>
Date: Wed, 2 Sep 2020 16:53:41 -0700
Subject: selftests/bpf: Add bpf_{update, delete}_map_elem in hashmap iter
program
Patch-mainline: v5.9-rc7
Git-commit: 4daab7132731ac5ec9384c8a070cdb9607dc38c8
References: bsc#1177028
Added bpf_{updata,delete}_map_elem to the very map element the
iter program is visiting. Due to rcu protection, the visited map
elements, although stale, should still contain correct values.
$ ./test_progs -n 4/18
#4/18 bpf_hash_map:OK
#4 bpf_iter:OK
Summary: 1/1 PASSED, 0 SKIPPED, 0 FAILED
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200902235341.2001534-1-yhs@fb.com
Acked-by: Gary Lin <glin@suse.com>
---
tools/testing/selftests/bpf/progs/bpf_iter_bpf_hash_map.c | 15 ++++++++++++++
1 file changed, 15 insertions(+)
--- a/tools/testing/selftests/bpf/progs/bpf_iter_bpf_hash_map.c
+++ b/tools/testing/selftests/bpf/progs/bpf_iter_bpf_hash_map.c
@@ -47,7 +47,10 @@ int dump_bpf_hash_map(struct bpf_iter__b
__u32 seq_num = ctx->meta->seq_num;
struct bpf_map *map = ctx->map;
struct key_t *key = ctx->key;
+ struct key_t tmp_key;
__u64 *val = ctx->value;
+ __u64 tmp_val = 0;
+ int ret;
if (in_test_mode) {
/* test mode is used by selftests to
@@ -61,6 +64,18 @@ int dump_bpf_hash_map(struct bpf_iter__b
if (key == (void *)0 || val == (void *)0)
return 0;
+ /* update the value and then delete the <key, value> pair.
+ * it should not impact the existing 'val' which is still
+ * accessible under rcu.
+ */
+ __builtin_memcpy(&tmp_key, key, sizeof(struct key_t));
+ ret = bpf_map_update_elem(&hashmap1, &tmp_key, &tmp_val, 0);
+ if (ret)
+ return 0;
+ ret = bpf_map_delete_elem(&hashmap1, &tmp_key);
+ if (ret)
+ return 0;
+
key_sum_a += key->a;
key_sum_b += key->b;
key_sum_c += key->c;