kunit: fix failure to build without printk

Previously KUnit assumed that printk would always be present, which is
not a valid assumption to make. Fix that by removing call to
vprintk_emit, and calling printk directly.

This fixes a build error[1] reported by Randy.

For context this change comes after much discussion. My first stab[2] at
this was just to make the KUnit logging code compile out; however, it
was agreed that if we were going to use vprintk_emit, then vprintk_emit
should provide a no-op stub, which lead to my second attempt[3]. In
response to me trying to stub out vprintk_emit, Sergey Senozhatsky
suggested a way for me to remove our usage of vprintk_emit, which led to
my third attempt at solving this[4].

In my third version of this patch[4], I completely removed vprintk_emit,
as suggested by Sergey; however, there was a bit of debate over whether
Sergey's solution was the best. The debate arose due to Sergey's version
resulting in a checkpatch warning, which resulted in a debate over
correct printk usage. Joe Perches offered an alternative fix which was
somewhat less far reaching than what Sergey had suggested and
importantly relied on continuing to use %pV. Much of the debated
centered around whether %pV should be widely used, and whether Sergey's
version would result in object size bloat. Ultimately, we decided to go
with Sergey's version.
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Link[1]: https://lore.kernel.org/linux-kselftest/c7229254-0d90-d90e-f3df-5b6d6fc0b51f@infradead.org/
Link[2]: https://lore.kernel.org/linux-kselftest/20190827174932.44177-1-brendanhiggins@google.com/
Link[3]: https://lore.kernel.org/linux-kselftest/20190827234835.234473-1-brendanhiggins@google.com/
Link[4]: https://lore.kernel.org/linux-kselftest/20190828093143.163302-1-brendanhiggins@google.com/
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Cc: Joe Perches <joe@perches.com>
Cc: Tim.Bird@sony.com
Signed-off-by: Brendan Higgins <brendanhiggins@google.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org> # build-tested
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

include/kunit/test.h

@@ -339,9 +339,8 @@ static inline void *kunit_kzalloc(struct kunit *test, size_t size, gfp_t gfp)
 
 void kunit_cleanup(struct kunit *test);
 
-void __printf(3, 4) kunit_printk(const char *level,
-				 const struct kunit *test,
-				 const char *fmt, ...);
+#define kunit_printk(lvl, test, fmt, ...) \
+	printk(lvl "\t# %s: " fmt, (test)->name, ##__VA_ARGS__)
 
 /**
  * kunit_info() - Prints an INFO level message associated with @test.

lib/kunit/test.c

@@ -16,36 +16,12 @@ static void kunit_set_failure(struct kunit *test)
 	WRITE_ONCE(test->success, false);
 }
 
-static int kunit_vprintk_emit(int level, const char *fmt, va_list args)
-{
-	return vprintk_emit(0, level, NULL, 0, fmt, args);
-}
-
-static int kunit_printk_emit(int level, const char *fmt, ...)
-{
-	va_list args;
-	int ret;
-
-	va_start(args, fmt);
-	ret = kunit_vprintk_emit(level, fmt, args);
-	va_end(args);
-
-	return ret;
-}
-
-static void kunit_vprintk(const struct kunit *test,
-			  const char *level,
-			  struct va_format *vaf)
-{
-	kunit_printk_emit(level[1] - '0', "\t# %s: %pV", test->name, vaf);
-}
-
 static void kunit_print_tap_version(void)
 {
 	static bool kunit_has_printed_tap_version;
 
 	if (!kunit_has_printed_tap_version) {
-		kunit_printk_emit(LOGLEVEL_INFO, "TAP version 14\n");
+		pr_info("TAP version 14\n");
 		kunit_has_printed_tap_version = true;
 	}
 }
@@ -64,10 +40,8 @@ static size_t kunit_test_cases_len(struct kunit_case *test_cases)
 static void kunit_print_subtest_start(struct kunit_suite *suite)
 {
 	kunit_print_tap_version();
-	kunit_printk_emit(LOGLEVEL_INFO, "\t# Subtest: %s\n", suite->name);
-	kunit_printk_emit(LOGLEVEL_INFO,
-			  "\t1..%zd\n",
-			  kunit_test_cases_len(suite->test_cases));
+	pr_info("\t# Subtest: %s\n", suite->name);
+	pr_info("\t1..%zd\n", kunit_test_cases_len(suite->test_cases));
 }
 
 static void kunit_print_ok_not_ok(bool should_indent,
@@ -87,9 +61,7 @@ static void kunit_print_ok_not_ok(bool should_indent,
 	else
 		ok_not_ok = "not ok";
 
-	kunit_printk_emit(LOGLEVEL_INFO,
-			  "%s%s %zd - %s\n",
-			  indent, ok_not_ok, test_number, description);
+	pr_info("%s%s %zd - %s\n", indent, ok_not_ok, test_number, description);
 }
 
 static bool kunit_suite_has_succeeded(struct kunit_suite *suite)
@@ -133,11 +105,11 @@ static void kunit_print_string_stream(struct kunit *test,
 		kunit_err(test,
 			  "Could not allocate buffer, dumping stream:\n");
 		list_for_each_entry(fragment, &stream->fragments, node) {
-			kunit_err(test, fragment->fragment);
+			kunit_err(test, "%s", fragment->fragment);
 		}
 		kunit_err(test, "\n");
 	} else {
-		kunit_err(test, buf);
+		kunit_err(test, "%s", buf);
 		kunit_kfree(test, buf);
 	}
 }
@@ -504,20 +476,3 @@ void kunit_cleanup(struct kunit *test)
 		kunit_resource_free(test, resource);
 	}
 }
-
-void kunit_printk(const char *level,
-		  const struct kunit *test,
-		  const char *fmt, ...)
-{
-	struct va_format vaf;
-	va_list args;
-
-	va_start(args, fmt);
-
-	vaf.fmt = fmt;
-	vaf.va = &args;
-
-	kunit_vprintk(test, level, &vaf);
-
-	va_end(args);
-}