Message-ID: <Z8nQ0vCNgz4lEJEj@pathway.suse.cz>
Date: Thu, 6 Mar 2025 17:44:02 +0100
From: Petr Mladek <pmladek@...e.com>
To: Tamir Duberstein <tamird@...il.com>
Cc: Arpitha Raghunandan <98.arpi@...il.com>,
	David Gow <davidgow@...gle.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
	Rasmus Villemoes <linux@...musvillemoes.dk>,
	Sergey Senozhatsky <senozhatsky@...omium.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Shuah Khan <shuah@...nel.org>, Jonathan Corbet <corbet@....net>,
	Geert Uytterhoeven <geert@...ux-m68k.org>,
	Madhavan Srinivasan <maddy@...ux.ibm.com>,
	Michael Ellerman <mpe@...erman.id.au>,
	Nicholas Piggin <npiggin@...il.com>,
	Christophe Leroy <christophe.leroy@...roup.eu>,
	Naveen N Rao <naveen@...nel.org>,
	Brendan Higgins <brendan.higgins@...ux.dev>,
	linux-kernel@...r.kernel.org, linux-kselftest@...r.kernel.org,
	linux-doc@...r.kernel.org, linux-m68k@...ts.linux-m68k.org,
	linuxppc-dev@...ts.ozlabs.org
Subject: Re: [PATCH v5 2/3] printf: break kunit into test cases

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.
> 
> Signed-off-by: Tamir Duberstein <tamird@...il.com>
> ---
>  lib/tests/printf_kunit.c | 331 +++++++++++++++++------------------------------
>  1 file changed, 121 insertions(+), 210 deletions(-)
> 
> diff --git a/lib/tests/printf_kunit.c b/lib/tests/printf_kunit.c
> index 287bbfb61148..013df6f6dd49 100644
> --- a/lib/tests/printf_kunit.c
> +++ b/lib/tests/printf_kunit.c
> @@ -38,13 +38,8 @@ static unsigned int total_tests;
>  static char *test_buffer;
>  static char *alloced_buffer;
>  
> -static struct kunit *kunittest;
> -
> -#define tc_fail(fmt, ...) \
> -	KUNIT_FAIL(kunittest, fmt, ##__VA_ARGS__)
> -
> -static void __printf(4, 0)
> -do_test(int bufsize, const char *expect, int elen,
> +static void __printf(5, 0)
> +do_test(struct kunit *kunittest, int bufsize, const char *expect, int elen,
>  	const char *fmt, va_list ap)
>  {
>  	va_list aq;
> @@ -58,59 +53,64 @@ do_test(int bufsize, const char *expect, int elen,
[...]
>  
>  	if (memcmp(test_buffer, expect, written)) {
> -		tc_fail("vsnprintf(buf, %d, \"%s\", ...) wrote '%s', expected '%.*s'",
> -			bufsize, fmt, test_buffer, written, expect);
> +		KUNIT_FAIL(kunittest, "vsnprintf(buf, %d, \"%s\", ...) wrote '%s', expected '%.*s'",
> +			   bufsize, fmt, test_buffer, written, expect);
>  		return;
>  	}
>  }
>  
> -static void __printf(3, 4)
> -__test(const char *expect, int elen, const char *fmt, ...)
> +static void __printf(4, 0)

This should be:

static void __printf(4, 5)

The 2nd parameter is zero when the variable list of parameters is
passed using va_list.

> +__test(struct kunit *kunittest, const char *expect, int elen, const char *fmt, ...)
>  {
>  	va_list ap;
>  	int rand;
>  	char *p;

> @@ -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;
>  	}
> -
> -	return 0;
>  }
>  
> -static int
> -plain_hash(void)
> -{
> -	char buf[PLAIN_BUF_SIZE];
> -	int ret;
> -
> -	ret = plain_hash_to_buffer(PTR, buf, PLAIN_BUF_SIZE);
> -	if (ret)
> -		return ret;
> -
> -	if (strncmp(buf, PTR_STR, PTR_WIDTH) == 0)
> -		return -1;
> -
> -	return 0;
> -}
> -
> -/*
> - * We can't use test() to test %p because we don't know what output to expect
> - * after an address is hashed.
> - */
>  static void
> -plain(void)
> +hash_pointer(struct kunit *kunittest)
>  {
> -	int err;
> +	if (no_hash_pointers)
> +		kunit_skip(kunittest, "hash pointers disabled");
>  
> -	if (no_hash_pointers) {
> -		kunit_warn(kunittest, "skipping plain 'p' tests");
> -		return;
> -	}
> +	char buf[PLAIN_BUF_SIZE];
>  
> -	err = plain_hash();
> -	if (err) {
> -		tc_fail("plain 'p' does not appear to be hashed");
> -		return;
> -	}
> +	plain_hash_to_buffer(kunittest, PTR, buf, PLAIN_BUF_SIZE);
>  
> -	err = plain_format();
> -	if (err) {
> -		tc_fail("hashing plain 'p' has unexpected format");
> -	}
> +	/*
> +	 * We can't use test() to test %p because we don't know what output to expect
> +	 * after an address is hashed.
> +	 */

The code does not longer print a reasonable error message on failure.
I would extend the comment to make it easier to understand the
meaning. Also I would use the imperative style. Something like:

	/*
	 * The hash of %p is unpredictable, therefore test() cannot be used.
	 * Instead, verify that the first 32 bits are zeros on a 64-bit system,
	 * and confirm the non-hashed value is not printed.
	 */
> +
> +	KUNIT_EXPECT_MEMEQ(kunittest, buf, ZEROS, strlen(ZEROS));
> +	KUNIT_EXPECT_MEMNEQ(kunittest, buf+strlen(ZEROS), PTR_STR, PTR_WIDTH);

This looks wrong. It should be either:

	KUNIT_EXPECT_MEMNEQ(kunittest, buf, PTR_STR, PTR_WIDTH);

or

	KUNIT_EXPECT_MEMNEQ(kunittest,
			    buf + strlen(ZEROS),
			    PTR_STR + strlen(ZEROS),
			    PTR_WIDTH - strlen(ZEROS));

I would use the 1st variant. It is easier and it works the same way
as the original check.

Anyway, it is a great clean up of the pointer tests. I have wanted to do it
since a long time but I never found time.

>  }
>  
>  static void
> -test_hashed(const char *fmt, const void *p)
> +test_hashed(struct kunit *kunittest, const char *fmt, const void *p)
>  {
>  	char buf[PLAIN_BUF_SIZE];
> -	int ret;
>  
> -	/*
> -	 * No need to increase failed test counter since this is assumed
> -	 * to be called after plain().
> -	 */
> -	ret = plain_hash_to_buffer(p, buf, PLAIN_BUF_SIZE);
> -	if (ret)
> -		return;
> +	plain_hash_to_buffer(kunittest, p, buf, PLAIN_BUF_SIZE);
>  
>  	test(buf, fmt, p);
>  }
> @@ -739,11 +664,9 @@ flags(void)
>  							(unsigned long) gfp);
>  	gfp |= __GFP_HIGH;
>  	test(cmp_buffer, "%pGg", &gfp);
> -
> -	kfree(cmp_buffer);

I belive that the kfree() should stay. Otherwise, the test leaks memory
in every run.

>  }
>  
> -static void fwnode_pointer(void)
> +static void fwnode_pointer(struct kunit *kunittest)
>  {
>  	const struct software_node first = { .name = "first" };
>  	const struct software_node second = { .name = "second", .parent = &first };

Otherwise, it looks good to me.

Best Regards,
Petr

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