printk: Declare log_wait properly

kernel/printk/printk.c:365:1: warning: symbol 'log_wait' was not declared. Should it be static?

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20220924000454.3319186-3-john.ogness@linutronix.de

Author: KAGA-KOKO

fs/proc/kmsg.c

@@ -18,8 +18,6 @@
 #include <linux/uaccess.h>
 #include <asm/io.h>
 
-extern wait_queue_head_t log_wait;
-
 static int kmsg_open(struct inode * inode, struct file * file)
 {
 	return do_syslog(SYSLOG_ACTION_OPEN, NULL, 0, SYSLOG_FROM_PROC);

include/linux/syslog.h

@@ -8,6 +8,8 @@
 #ifndef _LINUX_SYSLOG_H
 #define _LINUX_SYSLOG_H
 
+#include <linux/wait.h>
+
 /* Close the log.  Currently a NOP. */
 #define SYSLOG_ACTION_CLOSE          0
 /* Open the log. Currently a NOP. */
@@ -35,5 +37,6 @@
 #define SYSLOG_FROM_PROC             1
 
 int do_syslog(int type, char __user *buf, int count, int source);
+extern wait_queue_head_t log_wait;
 
 #endif /* _LINUX_SYSLOG_H */