tty: move some tty-only functions to drivers/tty/tty.h

The flow change and restricted_tty_write() logic is internal to the tty
core only, so move it out of the include/linux/tty.h file.

Cc: Jiri Slaby <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20210408125134.3016837-12-gregkh@linuxfoundation.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/tty.h

@@ -40,6 +40,21 @@ enum {
 	TTY_LOCK_SLAVE,
 };
 
+/* Values for tty->flow_change */
+#define TTY_THROTTLE_SAFE	1
+#define TTY_UNTHROTTLE_SAFE	2
+
+static inline void __tty_set_flow_change(struct tty_struct *tty, int val)
+{
+	tty->flow_change = val;
+}
+
+static inline void tty_set_flow_change(struct tty_struct *tty, int val)
+{
+	tty->flow_change = val;
+	smp_mb();
+}
+
 int tty_ldisc_lock(struct tty_struct *tty, unsigned long timeout);
 void tty_ldisc_unlock(struct tty_struct *tty);
 
@@ -57,4 +72,6 @@ static inline void tty_audit_tiocsti(struct tty_struct *tty, char ch)
 }
 #endif
 
+ssize_t redirected_tty_write(struct kiocb *, struct iov_iter *);
+
 #endif

drivers/tty/tty_ioctl.c

@@ -21,6 +21,7 @@
 #include <linux/bitops.h>
 #include <linux/mutex.h>
 #include <linux/compat.h>
+#include "tty.h"
 
 #include <asm/io.h>
 #include <linux/uaccess.h>

include/linux/tty.h

@@ -349,21 +349,6 @@ struct tty_file_private {
 #define TTY_LDISC_CHANGING	20	/* Change pending - non-block IO */
 #define TTY_LDISC_HALTED	22	/* Line discipline is halted */
 
-/* Values for tty->flow_change */
-#define TTY_THROTTLE_SAFE 1
-#define TTY_UNTHROTTLE_SAFE 2
-
-static inline void __tty_set_flow_change(struct tty_struct *tty, int val)
-{
-	tty->flow_change = val;
-}
-
-static inline void tty_set_flow_change(struct tty_struct *tty, int val)
-{
-	tty->flow_change = val;
-	smp_mb();
-}
-
 static inline bool tty_io_nonblock(struct tty_struct *tty, struct file *file)
 {
 	return file->f_flags & O_NONBLOCK ||
@@ -395,7 +380,6 @@ extern struct tty_struct *tty_kopen_exclusive(dev_t device);
 extern struct tty_struct *tty_kopen_shared(dev_t device);
 extern void tty_kclose(struct tty_struct *tty);
 extern int tty_dev_name_to_number(const char *name, dev_t *number);
-extern ssize_t redirected_tty_write(struct kiocb *, struct iov_iter *);
 #else
 static inline void tty_kref_put(struct tty_struct *tty)
 { }