Re: [PATCH bpf-next v8 10/10] selftests/bpf: test case for register_bpf_struct_ops().

[Martin KaFai Lau <martin.lau@linux.dev>]

On 10/30/23 12:28 PM, thinker.li@gmail.com wrote:
> diff --git a/tools/testing/selftests/bpf/prog_tests/test_struct_ops_module.c b/tools/testing/selftests/bpf/prog_tests/test_struct_ops_module.c
> new file mode 100644
> index 000000000000..3a00dc294583
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/prog_tests/test_struct_ops_module.c
> @@ -0,0 +1,39 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/* Copyright (c) 2023 Meta Platforms, Inc. and affiliates. */
> +#include <test_progs.h>
> +#include <time.h>
> +
> +#include "rcu_tasks_trace_gp.skel.h"
> +#include "struct_ops_module.skel.h"
> +
> +static void test_regular_load(void)
> +{
> +	struct struct_ops_module *skel;
> +	struct bpf_link *link;
> +	DECLARE_LIBBPF_OPTS(bpf_object_open_opts, opts);
> +	int err;
> +
> +	skel = struct_ops_module__open_opts(&opts);
> +	if (!ASSERT_OK_PTR(skel, "struct_ops_module_open"))
> +		return;
> +	err = struct_ops_module__load(skel);
> +	if (!ASSERT_OK(err, "struct_ops_module_load"))
> +		return;
> +
> +	link = bpf_map__attach_struct_ops(skel->maps.testmod_1);
> +	ASSERT_OK_PTR(link, "attach_test_mod_1");
> +
> +	/* test_2() will be called from bpf_dummy_reg() in bpf_testmod.c */
> +	ASSERT_EQ(skel->bss->test_2_result, 7, "test_2_result");
> +
> +	bpf_link__destroy(link);
> +
> +	struct_ops_module__destroy(skel);
> +}
> +
> +void serial_test_struct_ops_module(void)
> +{
> +	if (test__start_subtest("regular_load"))
> +		test_regular_load();

Could it also add some negative tests, e.g. missing 'struct 
bpf_struct_ops_common_value', reg() when the module is gone...etc.

[ ... ]

> +/* This function will trigger call_rcu_tasks_trace() in the kernel */
> +static int kern_sync_rcu_tasks_trace(void)

With patch 4, is it still needed?

> +{
> +	struct rcu_tasks_trace_gp *rcu;
> +	time_t start;
> +	long gp_seq;
> +	LIBBPF_OPTS(bpf_test_run_opts, opts);
> +
> +	rcu = rcu_tasks_trace_gp__open_and_load();
> +	if (IS_ERR(rcu))
> +		return -EFAULT;
> +	if (rcu_tasks_trace_gp__attach(rcu))
> +		return -EFAULT;
> +
> +	gp_seq = READ_ONCE(rcu->bss->gp_seq);
> +
> +	if (bpf_prog_test_run_opts(bpf_program__fd(rcu->progs.do_call_rcu_tasks_trace),
> +				   &opts))
> +		return -EFAULT;
> +	if (opts.retval != 0)
> +		return -EFAULT;
> +
> +	start = time(NULL);
> +	while ((start + 2) > time(NULL) &&
> +	       gp_seq == READ_ONCE(rcu->bss->gp_seq))
> +		sched_yield();
> +
> +	rcu_tasks_trace_gp__destroy(rcu);
> +
> +	return 0;
> +}
> +
>   /*
>    * Trigger synchronize_rcu() in kernel.
>    */
>   int kern_sync_rcu(void)
>   {
> +	if (kern_sync_rcu_tasks_trace())
> +		return -EFAULT;
>   	return syscall(__NR_membarrier, MEMBARRIER_CMD_SHARED, 0, 0);
>   }