Re: [PATCH net-next v5 17/21] lib/bitmap: add tests for IP tunnel flags conversion helpers

Yury Norov
2024-02-28T16:38:51Z

On Thu, Feb 01, 2024 at 01:22:12PM +0100, Alexander Lobakin wrote:
> Now that there are helpers for converting IP tunnel flags between the
> old __be16 format and the bitmap format, make sure they work as expected
> by adding a couple of tests to the bitmap testing suite. The helpers are
> all inline, so no dependencies on the related CONFIG_* (or a standalone
> module) are needed.
>
> Cover three possible cases:
>
> 1. No bits past BIT(15) are set, VTI/SIT bits are not set. This
> conversion is almost a direct assignment.
> 2. No bits past BIT(15) are set, but VTI/SIT bit is set. During the
> conversion, it must be transformed into BIT(16) in the bitmap,
> but still compatible with the __be16 format.
> 3. The bitmap has bits past BIT(15) set (not the VTI/SIT one). The
> result will be truncated.
> Note that currently __IP_TUNNEL_FLAG_NUM is 17 (incl. special),
> which means that the result of this case is currently
> semi-false-positive. When BIT(17) is finally here, it will be
> adjusted accordingly.
>
> Signed-off-by: Alexander Lobakin <aleksander.lobakin@intel.com>

So why testing IP tunnels stuff in lib/test_bitmap? I think it should
go with the rest of networking code.

> ---
> lib/test_bitmap.c | 105 ++++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 105 insertions(+)
>
> diff --git a/lib/test_bitmap.c b/lib/test_bitmap.c
> index 4ee1f8ceb51d..270afc0cba5c 100644
> --- a/lib/test_bitmap.c
> +++ b/lib/test_bitmap.c
> @@ -14,6 +14,8 @@
> #include <linux/string.h>
> #include <linux/uaccess.h>
>
> +#include <net/ip_tunnels.h>
> +
> #include "../tools/testing/selftests/kselftest_module.h"
>
> #define EXP1_IN_BITS (sizeof(exp1) * 8)
> @@ -1409,6 +1411,108 @@ static void __init test_bitmap_write_perf(void)
>
> #undef TEST_BIT_LEN
>
> +struct ip_tunnel_flags_test {
> + const u16 *src_bits;
> + const u16 *exp_bits;
> + u8 src_num;
> + u8 exp_num;
> + __be16 exp_val;
> + bool exp_comp:1;
> +};
> +
> +#define IP_TUNNEL_FLAGS_TEST(src, comp, eval, exp) { \
> + .src_bits = (src), \
> + .src_num = ARRAY_SIZE(src), \
> + .exp_comp = (comp), \
> + .exp_val = (eval), \
> + .exp_bits = (exp), \
> + .exp_num = ARRAY_SIZE(exp), \
> +}
> +
> +/* These are __be16-compatible and can be compared as is */
> +static const u16 ip_tunnel_flags_1[] __initconst = {
> + IP_TUNNEL_KEY_BIT,
> + IP_TUNNEL_STRICT_BIT,
> + IP_TUNNEL_ERSPAN_OPT_BIT,
> +};
> +
> +/*
> + * Due to the previous flags design limitation, setting either
> + * ``IP_TUNNEL_CSUM_BIT`` (on Big Endian) or ``IP_TUNNEL_DONT_FRAGMENT_BIT``
> + * (on Little) also sets VTI/ISATAP bit. In the bitmap implementation, they
> + * correspond to ``BIT(16)``, which is bigger than ``U16_MAX``, but still is
> + * backward-compatible.
> + */
> +#ifdef __BIG_ENDIAN
> +#define IP_TUNNEL_CONFLICT_BIT IP_TUNNEL_CSUM_BIT
> +#else
> +#define IP_TUNNEL_CONFLICT_BIT IP_TUNNEL_DONT_FRAGMENT_BIT
> +#endif
> +
> +static const u16 ip_tunnel_flags_2_src[] __initconst = {
> + IP_TUNNEL_CONFLICT_BIT,
> +};
> +
> +static const u16 ip_tunnel_flags_2_exp[] __initconst = {
> + IP_TUNNEL_CONFLICT_BIT,
> + IP_TUNNEL_SIT_ISATAP_BIT,
> +};
> +
> +/* Bits 17 and higher are not compatible with __be16 flags */
> +static const u16 ip_tunnel_flags_3_src[] __initconst = {
> + IP_TUNNEL_VXLAN_OPT_BIT,
> + 17,
> + 18,
> + 20,
> +};
> +
> +static const u16 ip_tunnel_flags_3_exp[] __initconst = {
> + IP_TUNNEL_VXLAN_OPT_BIT,
> +};
> +
> +static const struct ip_tunnel_flags_test ip_tunnel_flags_test[] __initconst = {
> + IP_TUNNEL_FLAGS_TEST(ip_tunnel_flags_1, true,
> + cpu_to_be16(BIT(IP_TUNNEL_KEY_BIT) |
> + BIT(IP_TUNNEL_STRICT_BIT) |
> + BIT(IP_TUNNEL_ERSPAN_OPT_BIT)),
> + ip_tunnel_flags_1),
> + IP_TUNNEL_FLAGS_TEST(ip_tunnel_flags_2_src, true, VTI_ISVTI,
> + ip_tunnel_flags_2_exp),
> + IP_TUNNEL_FLAGS_TEST(ip_tunnel_flags_3_src,
> + /*
> + * This must be set to ``false`` once
> + * ``__IP_TUNNEL_FLAG_NUM`` goes above 17.
> + */
> + true,
> + cpu_to_be16(BIT(IP_TUNNEL_VXLAN_OPT_BIT)),
> + ip_tunnel_flags_3_exp),
> +};
> +
> +static void __init test_ip_tunnel_flags(void)
> +{
> + for (u32 i = 0; i < ARRAY_SIZE(ip_tunnel_flags_test); i++) {
> + typeof(*ip_tunnel_flags_test) *test = &ip_tunnel_flags_test[i];
> + IP_TUNNEL_DECLARE_FLAGS(src) = { };
> + IP_TUNNEL_DECLARE_FLAGS(exp) = { };
> + IP_TUNNEL_DECLARE_FLAGS(out);
> +
> + for (u32 j = 0; j < test->src_num; j++)
> + __set_bit(test->src_bits[j], src);
> +
> + for (u32 j = 0; j < test->exp_num; j++)
> + __set_bit(test->exp_bits[j], exp);
> +
> + ip_tunnel_flags_from_be16(out, test->exp_val);
> +
> + expect_eq_uint(test->exp_comp,
> + ip_tunnel_flags_is_be16_compat(src));
> + expect_eq_uint((__force u16)test->exp_val,
> + (__force u16)ip_tunnel_flags_to_be16(src));
> +
> + __ipt_flag_op(expect_eq_bitmap, exp, out);
> + }
> +}
> +
> static void __init selftest(void)
> {
> test_zero_clear();
> @@ -1428,6 +1532,7 @@ static void __init selftest(void)
> test_bitmap_read_write();
> test_bitmap_read_perf();
> test_bitmap_write_perf();
> + test_ip_tunnel_flags();
>
> test_find_nth_bit();
> test_for_each_set_bit();
> --
> 2.43.0