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 <jslaby@suse.cz>
Acked-by: Laurentiu Tudor <laurentiu.tudor@nxp.com>
Acked-by: Alex Elder <elder@linaro.org>
Acked-by: Max Filippov <jcmvbkbc@gmail.com> # xtensa
Acked-by: David Sterba <dsterba@suse.com>
Acked-By: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Matt Turner <mattst88@gmail.com>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Chris Zankel <chris@zankel.net>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Samuel Iglesias Gonsalvez <siglesias@igalia.com>
Cc: Jens Taprogge <jens.taprogge@taprogge.org>
Cc: Karsten Keil <isdn@linux-pingi.de>
Cc: Scott Branden <scott.branden@broadcom.com>
Cc: Ulf Hansson <ulf.hansson@linaro.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: David Lin <dtwlin@gmail.com>
Cc: Johan Hovold <johan@kernel.org>
Cc: Jiri Kosina <jikos@kernel.org>
Cc: Shawn Guo <shawnguo@kernel.org>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Oliver Neukum <oneukum@suse.com>
Cc: Felipe Balbi <balbi@kernel.org>
Cc: Mathias Nyman <mathias.nyman@intel.com>
Cc: Marcel Holtmann <marcel@holtmann.org>
Cc: Johan Hedberg <johan.hedberg@gmail.com>
Cc: Luiz Augusto von Dentz <luiz.dentz@gmail.com>
Link: https://lore.kernel.org/r/20210505091928.22010-23-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

6 files changed, 8 insertions, 8 deletions

diff --git a/arch/alpha/kernel/srmcons.c b/arch/alpha/kernel/srmcons.c
index 438b10c44d73..2110b7e7f988 100644
--- a/arch/alpha/kernel/srmcons.c
+++ b/arch/alpha/kernel/srmcons.c
@@ -142,7 +142,7 @@ srmcons_write(struct tty_struct *tty,
 	return count;
 }
 
-static int
+static unsigned int
 srmcons_write_room(struct tty_struct *tty)
 {
 	return 512;
diff --git a/arch/m68k/emu/nfcon.c b/arch/m68k/emu/nfcon.c
index 57e8c8fb5eba..92636c89d65b 100644
--- a/arch/m68k/emu/nfcon.c
+++ b/arch/m68k/emu/nfcon.c
@@ -85,7 +85,7 @@ static int nfcon_tty_put_char(struct tty_struct *tty, unsigned char ch)
 	return 1;
 }
 
-static int nfcon_tty_write_room(struct tty_struct *tty)
+static unsigned int nfcon_tty_write_room(struct tty_struct *tty)
 {
 	return 64;
 }
diff --git a/arch/parisc/kernel/pdc_cons.c b/arch/parisc/kernel/pdc_cons.c
index 7ed404c60a9e..fe2ed0bbd07e 100644
--- a/arch/parisc/kernel/pdc_cons.c
+++ b/arch/parisc/kernel/pdc_cons.c
@@ -103,7 +103,7 @@ static int pdc_console_tty_write(struct tty_struct *tty, const unsigned char *bu
 	return count;
 }
 
-static int pdc_console_tty_write_room(struct tty_struct *tty)
+static unsigned int pdc_console_tty_write_room(struct tty_struct *tty)
 {
 	return 32768; /* no limit, no buffer used */
 }
diff --git a/arch/um/drivers/line.c b/arch/um/drivers/line.c
index 1c70a31e7c5b..2b8810ba5470 100644
--- a/arch/um/drivers/line.c
+++ b/arch/um/drivers/line.c
@@ -32,7 +32,7 @@ static irqreturn_t line_interrupt(int irq, void *data)
  *
  * Should be called while holding line->lock (this does not modify data).
  */
-static int write_room(struct line *line)
+static unsigned int write_room(struct line *line)
 {
 	int n;
 
@@ -47,11 +47,11 @@ static int write_room(struct line *line)
 	return n - 1;
 }
 
-int line_write_room(struct tty_struct *tty)
+unsigned int line_write_room(struct tty_struct *tty)
 {
 	struct line *line = tty->driver_data;
 	unsigned long flags;
-	int room;
+	unsigned int room;
 
 	spin_lock_irqsave(&line->lock, flags);
 	room = write_room(line);
diff --git a/arch/um/drivers/line.h b/arch/um/drivers/line.h
index 01d21e76144f..861edf329569 100644
--- a/arch/um/drivers/line.h
+++ b/arch/um/drivers/line.h
@@ -70,7 +70,7 @@ extern void line_set_termios(struct tty_struct *tty, struct ktermios * old);
 extern int line_chars_in_buffer(struct tty_struct *tty);
 extern void line_flush_buffer(struct tty_struct *tty);
 extern void line_flush_chars(struct tty_struct *tty);
-extern int line_write_room(struct tty_struct *tty);
+extern unsigned int line_write_room(struct tty_struct *tty);
 extern void line_throttle(struct tty_struct *tty);
 extern void line_unthrottle(struct tty_struct *tty);
 
diff --git a/arch/xtensa/platforms/iss/console.c b/arch/xtensa/platforms/iss/console.c
index a3dda25a4e45..98ac3a7fdb0a 100644
--- a/arch/xtensa/platforms/iss/console.c
+++ b/arch/xtensa/platforms/iss/console.c
@@ -100,7 +100,7 @@ static void rs_flush_chars(struct tty_struct *tty)
 {
 }
 
-static int rs_write_room(struct tty_struct *tty)
+static unsigned int rs_write_room(struct tty_struct *tty)
 {
 	/* Let's say iss can always accept 2K characters.. */
 	return 2 * 1024;