crng init: was: Re: [PATCH v5 2/3] printf: break kunit into test cases

Petr Mladek
2025-03-07T16:18:07Z

On Fri 2025-02-21 15:34:31, Tamir Duberstein wrote:
> Move all tests into `printf_test_cases`. This gives us nicer output in
> the event of a failure.
>
> Combine `plain_format` and `plain_hash` into `hash_pointer` since
> they're testing the same scenario.
>
> --- a/lib/tests/printf_kunit.c
> +++ b/lib/tests/printf_kunit.c
> @@ -178,7 +179,7 @@ test_number(void)
> }
>
> static void
> -test_string(void)
> +test_string(struct kunit *kunittest)
> {
> test("", "%s%.0s", "", "123");
> test("ABCD|abc|123", "%s|%.3s|%.*s", "ABCD", "abcdef", 3, "123456");
> @@ -215,29 +216,6 @@ test_string(void)
> #define ZEROS "00000000" /* hex 32 zero bits */
> #define ONES "ffffffff" /* hex 32 one bits */
>
> -static int
> -plain_format(void)
> -{
> - char buf[PLAIN_BUF_SIZE];
> - int nchars;
> -
> - nchars = snprintf(buf, PLAIN_BUF_SIZE, "%p", PTR);
> -
> - if (nchars != PTR_WIDTH)
> - return -1;
> -
> - if (strncmp(buf, PTR_VAL_NO_CRNG, PTR_WIDTH) == 0) {
> - kunit_warn(kunittest, "crng possibly not yet initialized. plain 'p' buffer contains \"%s\"",
> - PTR_VAL_NO_CRNG);
> - return 0;
> - }
> -
> - if (strncmp(buf, ZEROS, strlen(ZEROS)) != 0)
> - return -1;
> -
> - return 0;
> -}
> -
> #else
>
> #define PTR_WIDTH 8
> @@ -247,89 +225,44 @@ plain_format(void)
> #define ZEROS ""
> #define ONES ""
>
> -static int
> -plain_format(void)
> -{
> - /* Format is implicitly tested for 32 bit machines by plain_hash() */
> - return 0;
> -}
> -
> #endif /* BITS_PER_LONG == 64 */
>
> -static int
> -plain_hash_to_buffer(const void *p, char *buf, size_t len)
> +static void
> +plain_hash_to_buffer(struct kunit *kunittest, const void *p, char *buf, size_t len)
> {
> - int nchars;
> -
> - nchars = snprintf(buf, len, "%p", p);
> -
> - if (nchars != PTR_WIDTH)
> - return -1;
> + KUNIT_ASSERT_EQ(kunittest, snprintf(buf, len, "%p", p), PTR_WIDTH);
>
> if (strncmp(buf, PTR_VAL_NO_CRNG, PTR_WIDTH) == 0) {
> kunit_warn(kunittest, "crng possibly not yet initialized. plain 'p' buffer contains \"%s\"",
> PTR_VAL_NO_CRNG);
> - return 0;

I have simulated the not-yet-initialized crng and got:

[ 80.109760] printf_kunit: module verification failed: signature and/or required key missing - tainting kernel
[ 80.114218] KTAP version 1
[ 80.114743] 1..1
[ 80.116124] KTAP version 1
[ 80.116752] # Subtest: printf
[ 80.117239] # module: printf_kunit
[ 80.117256] 1..28
[ 80.120924] ok 1 test_basic
[ 80.121495] ok 2 test_number
[ 80.122741] ok 3 test_string
[ 80.123498] # hash_pointer: crng possibly not yet initialized. plain 'p' buffer contains "(____ptrval____)"
[ 80.124044] # hash_pointer: EXPECTATION FAILED at lib/tests/printf_kunit.c:256
Expected buf == "00000000", but
buf ==
<28><5f><5f><5f><5f><70><74><72>
"00000000" ==
<30><30><30><30><30><30><30><30>
[ 80.125888] not ok 4 hash_pointer
[ 80.129831] ok 5 null_pointer
[ 80.130253] ok 6 error_pointer
[ 80.131221] # invalid_pointer: crng possibly not yet initialized. plain 'p' buffer contains "(____ptrval____)"
[ 80.132168] ok 7 invalid_pointer
[ 80.135149] ok 8 symbol_ptr
[ 80.136016] ok 9 kernel_ptr
[ 80.136868] ok 10 struct_resource
[ 80.137768] ok 11 struct_range
[ 80.138613] ok 12 addr
[ 80.139370] ok 13 escaped_str
[ 80.140054] ok 14 hex_string
[ 80.140601] ok 15 mac
[ 80.141162] ok 16 ip4
[ 80.141670] ok 17 ip6
[ 80.142221] ok 18 uuid
[ 80.143090] ok 19 dentry
[ 80.143963] ok 20 struct_va_format
[ 80.144523] ok 21 time_and_date
[ 80.145043] ok 22 struct_clk
[ 80.145589] ok 23 bitmap
[ 80.146087] ok 24 netdev_features
[ 80.146572] ok 25 flags
[ 80.146980] # errptr: crng possibly not yet initialized. plain 'p' buffer contains "(____ptrval____)"
[ 80.147412] ok 26 errptr
[ 80.148548] ok 27 fwnode_pointer
[ 80.149086] ok 28 fourcc_pointer
[ 80.149090] # printf: ran 448 tests
[ 80.149099] # printf: pass:27 fail:1 skip:0 total:28
[ 80.149102] # Totals: pass:27 fail:1 skip:0 total:28
[ 80.149106] not ok 1 printf

=> One test failed even though vspritf() worked as expected.

The "EXPECTATION FAILED" message was a bit tricky because
it printed "<28><5f><5f><5f><5f><70><74><72>" instead of "(____ptrval____)".

Two tests succeeded even after a warning message which would make people
to investigate it.

I suggest to rather skip the test in this case. Something like:

if (strncmp(buf, PTR_VAL_NO_CRNG, PTR_WIDTH) == 0) {
kunit_skip(kunittest,
"crng possibly not yet initialized. plain 'p' buffer contains \"%s\"\n",
PTR_VAL_NO_CRNG);
}

It produces:

[ 140.555055] KTAP version 1
[ 140.555413] 1..1
[ 140.555796] KTAP version 1
[ 140.556115] # Subtest: printf
[ 140.556450] # module: printf_kunit
[ 140.556459] 1..28
[ 140.557757] ok 1 test_basic
[ 140.558072] ok 2 test_number
[ 140.558693] ok 3 test_string
[ 140.559278] ok 4 hash_pointer # SKIP crng possibly not yet initialized. plain 'p' buffer contains "(____ptrval____)"
[ 140.560949] ok 5 null_pointer
[ 140.561257] ok 6 error_pointer
[ 140.561880] ok 7 invalid_pointer # SKIP crng possibly not yet initialized. plain 'p' buffer contains "(____ptrval____)"
[ 140.564159] ok 8 symbol_ptr
[ 140.565248] ok 9 kernel_ptr
[ 140.566346] ok 10 struct_resource
[ 140.567642] ok 11 struct_range
[ 140.569141] ok 12 addr
[ 140.570395] ok 13 escaped_str
[ 140.571407] ok 14 hex_string
[ 140.572337] ok 15 mac
[ 140.573572] ok 16 ip4
[ 140.574712] ok 17 ip6
[ 140.575743] ok 18 uuid
[ 140.577164] ok 19 dentry
[ 140.578248] ok 20 struct_va_format
[ 140.579400] ok 21 time_and_date
[ 140.580507] ok 22 struct_clk
[ 140.581706] ok 23 bitmap
[ 140.582739] ok 24 netdev_features
[ 140.583808] ok 25 flags
[ 140.585274] ok 26 errptr # SKIP crng possibly not yet initialized. plain 'p' buffer contains "(____ptrval____)"
[ 140.588403] ok 27 fwnode_pointer
[ 140.592141] ok 28 fourcc_pointer
[ 140.592758] # printf: ran 408 tests
[ 140.593219] # printf: pass:25 fail:0 skip:3 total:28
[ 140.593706] # Totals: pass:25 fail:0 skip:3 total:28
[ 140.594280] ok 1 printf

Best Regards,
Petr