tty: make tty_operations::write_room return uint

Line disciplines expect a positive value or zero returned from
tty->ops->write_room (invoked by tty_write_room). So make this
assumption explicit by using unsigned int as a return value. Both of
tty->ops->write_room and tty_write_room.

Signed-off-by: Jiri Slaby <[email protected]>
Acked-by: Laurentiu Tudor <[email protected]>
Acked-by: Alex Elder <[email protected]>
Acked-by: Max Filippov <[email protected]> # xtensa
Acked-by: David Sterba <[email protected]>
Acked-By: Anton Ivanov <[email protected]>
Acked-by: Geert Uytterhoeven <[email protected]>
Cc: Richard Henderson <[email protected]>
Cc: Ivan Kokshaysky <[email protected]>
Cc: Matt Turner <[email protected]>
Cc: "James E.J. Bottomley" <[email protected]>
Cc: Helge Deller <[email protected]>
Cc: Jeff Dike <[email protected]>
Cc: Richard Weinberger <[email protected]>
Cc: Chris Zankel <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: Samuel Iglesias Gonsalvez <[email protected]>
Cc: Jens Taprogge <[email protected]>
Cc: Karsten Keil <[email protected]>
Cc: Scott Branden <[email protected]>
Cc: Ulf Hansson <[email protected]>
Cc: "David S. Miller" <[email protected]>
Cc: Jakub Kicinski <[email protected]>
Cc: Heiko Carstens <[email protected]>
Cc: Vasily Gorbik <[email protected]>
Cc: Christian Borntraeger <[email protected]>
Cc: David Lin <[email protected]>
Cc: Johan Hovold <[email protected]>
Cc: Jiri Kosina <[email protected]>
Cc: Shawn Guo <[email protected]>
Cc: Sascha Hauer <[email protected]>
Cc: Oliver Neukum <[email protected]>
Cc: Felipe Balbi <[email protected]>
Cc: Mathias Nyman <[email protected]>
Cc: Marcel Holtmann <[email protected]>
Cc: Johan Hedberg <[email protected]>
Cc: Luiz Augusto von Dentz <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

1 files changed, 2 insertions, 2 deletions

diff --git a/include/linux/tty_driver.h b/include/linux/tty_driver.h
index 653fa5af3a22..ea5b15c72764 100644
--- a/include/linux/tty_driver.h
+++ b/include/linux/tty_driver.h
@@ -89,7 +89,7 @@
  *
  *	Note: Do not call this function directly, call tty_driver_flush_chars
  * 
- * int  (*write_room)(struct tty_struct *tty);
+ * unsigned int  (*write_room)(struct tty_struct *tty);
  *
  * 	This routine returns the numbers of characters the tty driver
  * 	will accept for queuing to be written.  This number is subject
@@ -256,7 +256,7 @@ struct tty_operations {
 		      const unsigned char *buf, int count);
 	int  (*put_char)(struct tty_struct *tty, unsigned char ch);
 	void (*flush_chars)(struct tty_struct *tty);
-	int  (*write_room)(struct tty_struct *tty);
+	unsigned int (*write_room)(struct tty_struct *tty);
 	int  (*chars_in_buffer)(struct tty_struct *tty);
 	int  (*ioctl)(struct tty_struct *tty,
 		    unsigned int cmd, unsigned long arg);