[PATCH v1] printk: add dummy vprintk_emit for when CONFIG_PRINTK=n

[Brendan Higgins <brendanhiggins@google.com>]

Previously vprintk_emit was only defined when CONFIG_PRINTK=y, this
caused a build failure in kunit/test.c when CONFIG_PRINTK was not set.
Add a no-op dummy so that callers don't have to ifdef around this.

Note: It has been suggested that this go in through the kselftest tree
along with the KUnit patches, because KUnit depends on this. See the
second link for the discussion on this.

Reported-by: Randy Dunlap <rdunlap@infradead.org>
Link: https://lore.kernel.org/linux-kselftest/0352fae9-564f-4a97-715a-fabe016259df@kernel.org/T/#t
Link: https://lore.kernel.org/linux-kselftest/ECADFF3FD767C149AD96A924E7EA6EAF977A5D82@USCULXMSG01.am.sony.com/
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Brendan Higgins <brendanhiggins@google.com>
---
 include/linux/printk.h | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/include/linux/printk.h b/include/linux/printk.h
index cefd374c47b1..85b7970615a9 100644
--- a/include/linux/printk.h
+++ b/include/linux/printk.h
@@ -206,6 +206,13 @@ extern void printk_safe_init(void);
 extern void printk_safe_flush(void);
 extern void printk_safe_flush_on_panic(void);
 #else
+static inline __printf(5, 0)
+int vprintk_emit(int facility, int level,
+		 const char *dict, size_t dictlen,
+		 const char *fmt, va_list args)
+{
+	return 0;
+}
 static inline __printf(1, 0)
 int vprintk(const char *s, va_list args)
 {
-- 
2.23.0.187.g17f5b7556c-goog