[PATCH v3 11/14] printk: fix duplicate extern declarations

[Safocl Stollmannovic <safocl88@gmail.com>]

Compiling a kernel module with a C++ compiler results in a "duplicate
extern specifier" error.
This occurs because the code contains `extern asmlinkage`, and `asmlinkage`
expands to `extern C` when processed by a C++ compiler.
Since the code already contains sections that respond to a C++ compiler,
I believe it is a perfectly valid approach to gradually move toward a state
where kernel modules can be compiled by a C++ compiler without any issues.
The `extern` specifier must be removed.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=222257
Signed-off-by: Safocl Stollmannovic <safocl88@gmail.com>
---
 include/linux/printk.h | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/include/linux/printk.h b/include/linux/printk.h
index f594c1266..09a28181e 100644
--- a/include/linux/printk.h
+++ b/include/linux/printk.h
@@ -136,7 +136,7 @@ struct va_format {
 })
 
 #ifdef CONFIG_EARLY_PRINTK
-extern asmlinkage __printf(1, 2)
+asmlinkage __printf(1, 2)
 void early_printk(const char *fmt, ...);
 #else
 static inline __printf(1, 2) __cold
@@ -200,8 +200,8 @@ void __init setup_log_buf(int early);
 __printf(1, 2) void dump_stack_set_arch_desc(const char *fmt, ...);
 void dump_stack_print_info(const char *log_lvl);
 void show_regs_print_info(const char *log_lvl);
-extern asmlinkage void dump_stack_lvl(const char *log_lvl) __cold;
-extern asmlinkage void dump_stack(void) __cold;
+asmlinkage void dump_stack_lvl(const char *log_lvl) __cold;
+asmlinkage void dump_stack(void) __cold;
 void printk_trigger_flush(void);
 void console_try_replay_all(void);
 void printk_legacy_allow_panic_sync(void);
-- 
2.56.1