[PATCH 2/2] selftests/bpf: test bpf_for within spin lock section

[Emil Tsalapatis <emil@etsalapatis.com>]

Add a selftest to ensure BPF for loops within critical sections are
accepted by the verifier.

Signed-off-by: Emil Tsalapatis (Meta) <emil@etsalapatis.com>
---
 .../selftests/bpf/progs/verifier_spin_lock.c  | 26 +++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/tools/testing/selftests/bpf/progs/verifier_spin_lock.c b/tools/testing/selftests/bpf/progs/verifier_spin_lock.c
index 25599eac9a70..d9d7b05cf6d2 100644
--- a/tools/testing/selftests/bpf/progs/verifier_spin_lock.c
+++ b/tools/testing/selftests/bpf/progs/verifier_spin_lock.c
@@ -530,4 +530,30 @@ l1_%=:	exit;						\
 	: __clobber_all);
 }
 
+SEC("tc")
+__description("spin_lock: loop within a locked region")
+__success __failure_unpriv __msg_unpriv("")
+__retval(0)
+int bpf_loop_inside_locked_region(void)
+{
+	const int zero = 0;
+	struct val *val;
+	int i, j = 0;
+
+	val = bpf_map_lookup_elem(&map_spin_lock, &zero);
+	if (!val)
+		return -1;
+
+	bpf_spin_lock(&val->l);
+	bpf_for(i, 0, 10) {
+		j++;
+		/* Silence "unused variable" warnings. */
+		if (j == 10)
+			break;
+	}
+	bpf_spin_unlock(&val->l);
+
+	return 0;
+}
+
 char _license[] SEC("license") = "GPL";
-- 
2.47.1