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

[Petr Mladek <pmladek@suse.com>]

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