selftests/bpf: Add bpf_lookup_and_delete_elem tests

Add bpf selftests and extend existing ones for a new function
bpf_lookup_and_delete_elem() for (percpu) hash and (percpu) LRU hash map
types.
In test_lru_map and test_maps we add an element, lookup_and_delete it,
then check whether it's deleted.
The newly added lookup_and_delete prog tests practically do the same
thing but additionally use a BPF program to change the value of the
element for LRU maps.

Signed-off-by: Denis Salopek <denis.salopek@sartura.hr>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/d30d3e0060c1f750e133579623cf1c60ff58f3d9.1620763117.git.denis.salopek@sartura.hr

1 files changed, 17 insertions, 0 deletions

diff --git a/tools/testing/selftests/bpf/test_maps.c b/tools/testing/selftests/bpf/test_maps.c
index 51adc42b2b40..8410a730c82f 100644
--- a/tools/testing/selftests/bpf/test_maps.c
+++ b/tools/testing/selftests/bpf/test_maps.c
@@ -65,6 +65,13 @@ static void test_hashmap(unsigned int task, void *data)
 	assert(bpf_map_lookup_elem(fd, &key, &value) == 0 && value == 1234);
 
 	key = 2;
+	value = 1234;
+	/* Insert key=2 element. */
+	assert(bpf_map_update_elem(fd, &key, &value, BPF_ANY) == 0);
+
+	/* Check that key=2 matches the value and delete it */
+	assert(bpf_map_lookup_and_delete_elem(fd, &key, &value) == 0 && value == 1234);
+
 	/* Check that key=2 is not found. */
 	assert(bpf_map_lookup_elem(fd, &key, &value) == -1 && errno == ENOENT);
 
@@ -166,6 +173,16 @@ static void test_hashmap_percpu(unsigned int task, void *data)
 	/* Insert key=1 element. */
 	assert(!(expected_key_mask & key));
 	assert(bpf_map_update_elem(fd, &key, value, BPF_ANY) == 0);
+
+	/* Lookup and delete elem key=1 and check value. */
+	assert(bpf_map_lookup_and_delete_elem(fd, &key, value) == 0 &&
+	       bpf_percpu(value,0) == 100);
+
+	for (i = 0; i < nr_cpus; i++)
+		bpf_percpu(value,i) = i + 100;
+
+	/* Insert key=1 element which should not exist. */
+	assert(bpf_map_update_elem(fd, &key, value, BPF_NOEXIST) == 0);
 	expected_key_mask |= key;
 
 	/* BPF_NOEXIST means add new element if it doesn't exist. */