selftests/bpf: Add stacktrace map lookup_and_delete_elem test case

Add tests for stacktrace map lookup and delete:
1. use bpf_map_lookup_and_delete_elem to lookup and delete the target
   stack_id,
2. lookup the deleted stack_id again to double check.

Signed-off-by: Tao Chen <[email protected]>

Author: Tao Chen

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

@@ -3,14 +3,16 @@
 
 void test_stacktrace_map(void)
 {
-	int control_map_fd, stackid_hmap_fd, stackmap_fd, stack_amap_fd;
+	int control_map_fd, stackid_hmap_fd, stackmap_fd, stack_amap_fd, stack_key_map_fd;
 	const char *prog_name = "oncpu";
 	int err, prog_fd, stack_trace_len;
 	const char *file = "./test_stacktrace_map.bpf.o";
 	__u32 key, val, duration = 0;
 	struct bpf_program *prog;
 	struct bpf_object *obj;
 	struct bpf_link *link;
+	__u32 stack_id;
+	char val_buf[PERF_MAX_STACK_DEPTH * sizeof(struct bpf_stack_build_id)];
 
 	err = bpf_prog_test_load(file, BPF_PROG_TYPE_TRACEPOINT, &obj, &prog_fd);
 	if (CHECK(err, "prog_load", "err %d errno %d\n", err, errno))
@@ -41,6 +43,10 @@ void test_stacktrace_map(void)
 	if (CHECK_FAIL(stack_amap_fd < 0))
 		goto disable_pmu;
 
+	stack_key_map_fd = bpf_find_map(__func__, obj, "stack_key_map");
+	if (CHECK_FAIL(stack_key_map_fd < 0))
+		goto disable_pmu;
+
 	/* give some time for bpf program run */
 	sleep(1);
 
@@ -68,6 +74,19 @@ void test_stacktrace_map(void)
 		  "err %d errno %d\n", err, errno))
 		goto disable_pmu;
 
+	err = bpf_map_lookup_elem(stack_key_map_fd, &key, &stack_id);
+	if (CHECK(err, "stack_key_map lookup", "err %d errno %d\n", err, errno))
+		goto disable_pmu;
+
+	err = bpf_map_lookup_and_delete_elem(stackmap_fd, &stack_id, &val_buf);
+	if (CHECK(err, "stackmap lookup and delete",
+		  "err %d errno %d\n", err, errno))
+		goto disable_pmu;
+
+	err = bpf_map_lookup_elem(stackmap_fd, &stack_id, &val_buf);
+	CHECK((!err || errno != ENOENT), "stackmap lookup deleted stack_id",
+	      "err %d errno %d\n", err, errno);
+
 disable_pmu:
 	bpf_link__destroy(link);
 close_prog:

tools/testing/selftests/bpf/progs/test_stacktrace_map.c

@@ -38,6 +38,13 @@ struct {
 	__type(value, stack_trace_t);
 } stack_amap SEC(".maps");
 
+struct {
+	__uint(type, BPF_MAP_TYPE_ARRAY);
+	__uint(max_entries, 1);
+	__type(key, __u32);
+	__type(value, __u32);
+} stack_key_map SEC(".maps");
+
 /* taken from /sys/kernel/tracing/events/sched/sched_switch/format */
 struct sched_switch_args {
 	unsigned long long pad;
@@ -64,6 +71,7 @@ int oncpu(struct sched_switch_args *ctx)
 	/* The size of stackmap and stackid_hmap should be the same */
 	key = bpf_get_stackid(ctx, &stackmap, 0);
 	if ((int)key >= 0) {
+		bpf_map_update_elem(&stack_key_map, &val, &key, 0);
 		bpf_map_update_elem(&stackid_hmap, &key, &val, 0);
 		stack_p = bpf_map_lookup_elem(&stack_amap, &key);
 		if (stack_p)