[PATCH] printk: add dummy printk_force_console_enter/exit helpers

[Arnd Bergmann <arnd@kernel.org>]

From: Arnd Bergmann <arnd@arndb.de>

The newly added interface is broken when PRINTK is disabled:

drivers/tty/sysrq.c: In function '__handle_sysrq':
drivers/tty/sysrq.c:601:9: error: implicit declaration of function 'printk_force_console_enter' [-Wimplicit-function-declaration]
  601 |         printk_force_console_enter();
      |         ^~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/tty/sysrq.c:611:25: error: implicit declaration of function 'printk_force_console_exit' [-Wimplicit-function-declaration]
  611 |                         printk_force_console_exit();
      |                         ^~~~~~~~~~~~~~~~~~~~~~~~~

Add empty stub functions for both.

Fixes: ed76c07c6885 ("printk: Introduce FORCE_CON flag")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 include/linux/printk.h | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/include/linux/printk.h b/include/linux/printk.h
index 232e5fd06701..0f2d7bdcea54 100644
--- a/include/linux/printk.h
+++ b/include/linux/printk.h
@@ -232,6 +232,14 @@ static inline void printk_deferred_exit(void)
 {
 }
 
+static void printk_force_console_enter(void)
+{
+}
+
+static void printk_force_console_exit(void)
+{
+}
+
 static inline int printk_ratelimit(void)
 {
 	return 0;
-- 
2.39.5