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Message-ID: <Z6s2eqh0jkYHntUL@pathway.suse.cz>
Date: Tue, 11 Feb 2025 12:37:30 +0100
From: Petr Mladek <pmladek@...e.com>
To: Tamir Duberstein <tamird@...il.com>
Cc: 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>,
Geert Uytterhoeven <geert@...ux-m68k.org>,
linux-kernel@...r.kernel.org, linux-kselftest@...r.kernel.org
Subject: Re: [PATCH v6 1/2] scanf: convert self-test to KUnit
On Mon 2025-02-10 13:13:48, Tamir Duberstein wrote:
> Convert the scanf() self-test to a KUnit test.
>
> In the interest of keeping the patch reasonably-sized this doesn't
> refactor the tests into proper parameterized tests - it's all one big
> test case.
>
> Acked-by: Petr Mladek <pmladek@...e.com>
Please, remove this. The patchset has changed a lot and it is not
longer true.
> --- a/lib/test_scanf.c
> +++ b/lib/scanf_kunit.c
> @@ -15,67 +13,49 @@
[...]
> #define _check_numbers_template(arg_fmt, expect, str, fmt, n_args, ap) \
> do { \
> - pr_debug("\"%s\", \"%s\" ->\n", str, fmt); \
> + kunit_printk(KERN_DEBUG, test, "\"%s\", \"%s\" ->", str, fmt); \
The switch from pr_debug() to kunit_printk() causes printing huge
amount of messages even when the test passes.
[ 5780.664377] KTAP version 1
[ 5780.664891] 1..1
[ 5780.665376] KTAP version 1
[ 5780.665765] # Subtest: scanf
[ 5780.666104] # module: scanf_kunit
[ 5780.666112] 1..10
[ 5780.667354] # numbers_simple: "0", "%llu" ->
[ 5780.667371] # numbers_simple: 0
[ 5780.667923] # numbers_simple: "0", "%llu" ->
[ 5780.668321] # numbers_simple: 0
[ 5780.668803] # numbers_simple: "1", "%llu" ->
[ 5780.669175] # numbers_simple: 1
[ 5780.669624] # numbers_simple: "18446744073709551615", "%llu" ->
[... skipping 7500+ lines ...]
[ 5783.157777] # test_simple_strtol: simple_strtol("0x7fffffffffffffff", 0) -> 0x7fffffffffffffff
[ 5783.158229] # test_simple_strtol: simple_strtol("0x8000000000000001", 0) -> 0x8000000000000001
[ 5783.158683] # test_simple_strtol: simple_strtol("0x8000000000000000", 0) -> 0x8000000000000000
[ 5783.159131] # test_simple_strtol: simple_strtol("0x8000000000000000", 0) -> 0x8000000000000000
[ 5783.159586] # test_simple_strtol: simple_strtol("0x8000000000000001", 0) -> 0x8000000000000001
[ 5783.160048] # test_simple_strtol: simple_strtol("0x7fffffffffffffff", 0) -> 0x7fffffffffffffff
[ 5783.160506] # test_simple_strtol: simple_strtol("0xfffffffffffffffe", 0) -> 0xfffffffffffffffe
[ 5783.160957] # test_simple_strtol: simple_strtol("0x2", 0) -> 0x2
[ 5783.161467] # test_simple_strtol: simple_strtol("0xffffffffffffffff", 0) -> 0xffffffffffffffff
[ 5783.161806] # test_simple_strtol: simple_strtol("0x1", 0) -> 0x1
[ 5783.162564] ok 10 test_simple_strtol
[ 5783.163145] # scanf: pass:10 fail:0 skip:0 total:10
[ 5783.163537] # Totals: pass:22 fail:0 skip:0 total:22
[ 5783.164052] ok 1 scanf
Yes, it would help with debugging. But we should print these details
only when the test fails!
Partial solution might be to use pr_debug(). The messages will be
disabled by default and can be enabled via /sys/kernel/debug/dynamic_debug/control
Here is some POC:
>From 7ea79fd67c4a7d8dff9d9fa986bb8dc037087c47 Mon Sep 17 00:00:00 2001
From: Petr Mladek <pmladek@...e.com>
Date: Tue, 11 Feb 2025 12:24:40 +0100
Subject: [POC] kunit/scanf_knunit: Add kunit_debug() to allow using the
dynamic debug facility
Do not fill the kernel logbuffer with debug messages by default.
Allow to enable them via /sys/kernel/debug/dynamic_debug/control
The question is whether we want to print them into the kunit log.
FIXME: This use just a POC. The right solution should reduce
cut&paste.
---
include/kunit/test.h | 30 ++++++++++++++++++++++++++++++
lib/scanf_kunit.c | 6 +++---
2 files changed, 33 insertions(+), 3 deletions(-)
diff --git a/include/kunit/test.h b/include/kunit/test.h
index 58dbab60f853..23fa3d6b3735 100644
--- a/include/kunit/test.h
+++ b/include/kunit/test.h
@@ -637,6 +637,36 @@ void __printf(2, 3) kunit_log_append(struct string_stream *log, const char *fmt,
#define kunit_err(test, fmt, ...) \
kunit_printk(KERN_ERR, test, fmt, ##__VA_ARGS__)
+/*
+ * pr_debug and log to per-test or per-suite log buffer. Logging only done
+ * if CONFIG_KUNIT_DEBUGFS is 'y'; if it is 'n', no log is allocated/used.
+ *
+ * The special variant is needed to allow using the printk dynamic debug
+ * infrastructure, see CONFIG_DYNAMIC_DEBUG.
+ */
+#define kunit_log_debug(test_or_suite, fmt, ...) \
+ do { \
+ pr_debug(fmt, ##__VA_ARGS__); \
+ kunit_log_append((test_or_suite)->log, fmt, \
+ ##__VA_ARGS__); \
+ } while (0)
+
+#define kunit_printk_debug(test, fmt, ...) \
+ kunit_log_debug(test, KUNIT_SUBTEST_INDENT "# %s: " fmt, \
+ (test)->name, ##__VA_ARGS__)
+
+/**
+ * kunit_debug() - Prints an DEBUG level message associated with @test.
+ *
+ * @test: The test context object.
+ * @fmt: A printk() style format string.
+ *
+ * Prints an error level message.
+ */
+#define kunit_debug(test, fmt, ...) \
+ kunit_printk_debug(test, fmt, ##__VA_ARGS__)
+
+
/*
* Must be called at the beginning of each KUNIT_*_ASSERTION().
* Cf. KUNIT_CURRENT_LOC.
diff --git a/lib/scanf_kunit.c b/lib/scanf_kunit.c
index 7e2e7d891e41..e45f3c4f0437 100644
--- a/lib/scanf_kunit.c
+++ b/lib/scanf_kunit.c
@@ -42,10 +42,10 @@ _test(struct kunit *test, check_fn fn, const void *check_data, const char *strin
#define _check_numbers_template(arg_fmt, expect, str, fmt, n_args, ap) \
do { \
- kunit_printk(KERN_DEBUG, test, "\"%s\", \"%s\" ->", str, fmt); \
+ kunit_debug(test, "\"%s\", \"%s\" ->", str, fmt); \
for (; n_args > 0; n_args--, expect++) { \
typeof(*expect) got = *va_arg(ap, typeof(expect)); \
- kunit_printk(KERN_DEBUG, test, "\t" arg_fmt, got); \
+ kunit_debug(test, "\t" arg_fmt, got); \
KUNIT_EXPECT_EQ_MSG(test, got, *expect, \
"vsscanf(\"%s\", \"%s\", ...)", str, fmt); \
} \
@@ -677,7 +677,7 @@ do { \
\
len = snprintf(test_buffer, BUF_SIZE, gen_fmt, expect); \
got = (fn)(test_buffer, &endp, base); \
- kunit_printk(KERN_DEBUG, test, #fn "(\"%s\", %d) -> " gen_fmt, test_buffer, base, got); \
+ kunit_debug(test, #fn "(\"%s\", %d) -> " gen_fmt, test_buffer, base, got); \
if (got != (expect)) { \
KUNIT_FAIL(test, #fn "(\"%s\", %d): got " gen_fmt " expected " gen_fmt, \
test_buffer, base, got, expect); \
--
2.48.1
But when thinking more about it. I think that even pr_debug() is not
the right solution.
IMHO, we really want to print these details only when the test fails.
Best Regards,
Petr
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