selftests/bpf: Adds selftests to check termination of long running nested bpf loops

Adds tests checks for loops termination which are nested.

32/1    bpf_termination/bpf_termination:OK
32      bpf_termination:OK
Summary: 1/1 PASSED, 0 SKIPPED, 0 FAILED

Signed-off-by: Raj Sahu <[email protected]>
Signed-off-by: Siddharth Chintamaneni <[email protected]>

Author: sidchintamaneni

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

@@ -0,0 +1,39 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <test_progs.h>
+#include <sys/socket.h>
+
+#include "bpf_termination.skel.h"
+
+void test_loop_termination(void)
+{
+	struct bpf_termination *skel;
+	int err;
+	
+	skel = bpf_termination__open();
+	if (!ASSERT_OK_PTR(skel, "bpf_termination__open"))
+	        return;
+	
+	err = bpf_termination__load(skel);
+	if (!ASSERT_OK(err, "bpf_termination__load"))
+	        goto out;
+	
+	skel->bss->pid = getpid();
+	err = bpf_termination__attach(skel);
+	if (!ASSERT_OK(err, "bpf_termination__attach"))
+	        goto out;
+	
+	/* Triggers long running BPF program */
+	socket(AF_UNSPEC, SOCK_DGRAM, 0);
+
+	/* If the program is not terminated, it doesn't reach this point */
+	ASSERT_TRUE(true, "Program is terminated");
+out:
+       bpf_termination__destroy(skel);
+}
+
+void test_bpf_termination(void)
+{
+	if (test__start_subtest("bpf_termination"))
+		test_loop_termination();
+}

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

@@ -0,0 +1,47 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <stddef.h>
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+
+int pid;
+
+#define LOOPS_CNT 1 << 10
+
+static int callback_fn4(void *ctx) {
+	return 0;
+}
+
+static int callback_fn3(void *ctx) {
+
+	bpf_loop(LOOPS_CNT, callback_fn4, NULL, 0);
+	return 0;
+
+}
+
+
+static int callback_fn2(void *ctx) {
+
+	bpf_loop(LOOPS_CNT, callback_fn3, NULL, 0);
+	return 0;
+
+}
+
+static int callback_fn(void *ctx) {
+
+	bpf_loop(LOOPS_CNT, callback_fn2, NULL, 0);
+	return 0;
+
+}
+
+SEC("tp/syscalls/sys_enter_socket")
+int bpf_loop_lr(void *ctx) {
+
+	if ((bpf_get_current_pid_tgid() >> 32) != pid)
+		return 0;
+
+	bpf_loop(LOOPS_CNT, callback_fn, NULL, 0);
+
+	return 0;
+}
+
+char _license[] SEC("license") = "GPL";