tty: make tty_operations::write()'s count size_t

Unify with the rest of the code. Use size_t for counts and ssize_t for
retval.

Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20230810091510.13006-30-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

43 files changed, 82 insertions, 61 deletions

diff --git a/arch/alpha/kernel/srmcons.c b/arch/alpha/kernel/srmcons.c
index dea39008d93e..d6139dbae4ac 100644
--- a/arch/alpha/kernel/srmcons.c
+++ b/arch/alpha/kernel/srmcons.c
@@ -129,8 +129,8 @@ srmcons_do_write(struct tty_port *port, const char *buf, int count)
 	return count;
 }
 
-static int
-srmcons_write(struct tty_struct *tty, const u8 *buf, int count)
+static ssize_t
+srmcons_write(struct tty_struct *tty, const u8 *buf, size_t count)
 {
 	unsigned long flags;
 
diff --git a/arch/m68k/emu/nfcon.c b/arch/m68k/emu/nfcon.c
index 87398f834e36..3a74d493eb3e 100644
--- a/arch/m68k/emu/nfcon.c
+++ b/arch/m68k/emu/nfcon.c
@@ -70,7 +70,8 @@ static void nfcon_tty_close(struct tty_struct *tty, struct file *filp)
 {
 }
 
-static int nfcon_tty_write(struct tty_struct *tty, const u8 *buf, int count)
+static ssize_t nfcon_tty_write(struct tty_struct *tty, const u8 *buf,
+			       size_t count)
 {
 	nfputs(buf, count);
 	return count;
diff --git a/arch/um/drivers/line.c b/arch/um/drivers/line.c
index e5393b4ba9f8..b98545f3edb5 100644
--- a/arch/um/drivers/line.c
+++ b/arch/um/drivers/line.c
@@ -184,7 +184,7 @@ void line_flush_chars(struct tty_struct *tty)
 	line_flush_buffer(tty);
 }
 
-int line_write(struct tty_struct *tty, const u8 *buf, int len)
+ssize_t line_write(struct tty_struct *tty, const u8 *buf, size_t len)
 {
 	struct line *line = tty->driver_data;
 	unsigned long flags;
diff --git a/arch/um/drivers/line.h b/arch/um/drivers/line.h
index 8354024b6b35..e84fb9b4165e 100644
--- a/arch/um/drivers/line.h
+++ b/arch/um/drivers/line.h
@@ -64,7 +64,7 @@ extern void line_cleanup(struct tty_struct *tty);
 extern void line_hangup(struct tty_struct *tty);
 extern int line_setup(char **conf, unsigned nlines, char **def,
 		      char *init, char *name);
-extern int line_write(struct tty_struct *tty, const u8 *buf, int len);
+extern ssize_t line_write(struct tty_struct *tty, const u8 *buf, size_t len);
 extern unsigned 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);
diff --git a/arch/xtensa/platforms/iss/console.c b/arch/xtensa/platforms/iss/console.c
index 182ec57e2d5c..7d1f8b398a46 100644
--- a/arch/xtensa/platforms/iss/console.c
+++ b/arch/xtensa/platforms/iss/console.c
@@ -52,7 +52,7 @@ static void rs_close(struct tty_struct *tty, struct file * filp)
 }
 
 
-static int rs_write(struct tty_struct * tty, const u8 *buf, int count)
+static ssize_t rs_write(struct tty_struct * tty, const u8 *buf, size_t count)
 {
 	/* see drivers/char/serialX.c to reference original version */
 
diff --git a/drivers/char/ttyprintk.c b/drivers/char/ttyprintk.c
index 4f3dd93f1fd8..5af804c17a75 100644
--- a/drivers/char/ttyprintk.c
+++ b/drivers/char/ttyprintk.c
@@ -103,7 +103,7 @@ static void tpk_close(struct tty_struct *tty, struct file *filp)
 /*
  * TTY operations write function.
  */
-static int tpk_write(struct tty_struct *tty, const u8 *buf, int count)
+static ssize_t tpk_write(struct tty_struct *tty, const u8 *buf, size_t count)
 {
 	struct ttyprintk_port *tpkp = tty->driver_data;
 	unsigned long flags;
diff --git a/drivers/ipack/devices/ipoctal.c b/drivers/ipack/devices/ipoctal.c
index c3cf086e7e36..da308be6c487 100644
--- a/drivers/ipack/devices/ipoctal.c
+++ b/drivers/ipack/devices/ipoctal.c
@@ -458,7 +458,8 @@ static inline int ipoctal_copy_write_buffer(struct ipoctal_channel *channel,
 	return i;
 }
 
-static int ipoctal_write_tty(struct tty_struct *tty, const u8 *buf, int count)
+static ssize_t ipoctal_write_tty(struct tty_struct *tty, const u8 *buf,
+				 size_t count)
 {
 	struct ipoctal_channel *channel = tty->driver_data;
 	unsigned int char_copied;
diff --git a/drivers/isdn/capi/capi.c b/drivers/isdn/capi/capi.c
index 2f38e1cfe97a..2f3789515445 100644
--- a/drivers/isdn/capi/capi.c
+++ b/drivers/isdn/capi/capi.c
@@ -1077,12 +1077,13 @@ static void capinc_tty_close(struct tty_struct *tty, struct file *filp)
 	tty_port_close(&mp->port, tty, filp);
 }
 
-static int capinc_tty_write(struct tty_struct *tty, const u8 *buf, int count)
+static ssize_t capinc_tty_write(struct tty_struct *tty, const u8 *buf,
+				size_t count)
 {
 	struct capiminor *mp = tty->driver_data;
 	struct sk_buff *skb;
 
-	pr_debug("capinc_tty_write(count=%d)\n", count);
+	pr_debug("capinc_tty_write(count=%zu)\n", count);
 
 	spin_lock_bh(&mp->outlock);
 	skb = mp->outskb;
diff --git a/drivers/misc/bcm-vk/bcm_vk_tty.c b/drivers/misc/bcm-vk/bcm_vk_tty.c
index 44851b607cce..2bce835ca43e 100644
--- a/drivers/misc/bcm-vk/bcm_vk_tty.c
+++ b/drivers/misc/bcm-vk/bcm_vk_tty.c
@@ -186,7 +186,8 @@ static void bcm_vk_tty_doorbell(struct bcm_vk *vk, u32 db_val)
 		  VK_BAR0_REGSEG_DB_BASE + VK_BAR0_REGSEG_TTY_DB_OFFSET);
 }
 
-static int bcm_vk_tty_write(struct tty_struct *tty, const u8 *buffer, int count)
+static ssize_t bcm_vk_tty_write(struct tty_struct *tty, const u8 *buffer,
+				size_t count)
 {
 	int index;
 	struct bcm_vk *vk;
diff --git a/drivers/mmc/core/sdio_uart.c b/drivers/mmc/core/sdio_uart.c
index 90d2fe00c0b9..ef38dcd3a887 100644
--- a/drivers/mmc/core/sdio_uart.c
+++ b/drivers/mmc/core/sdio_uart.c
@@ -760,7 +760,8 @@ static void sdio_uart_hangup(struct tty_struct *tty)
 	tty_port_hangup(&port->port);
 }
 
-static int sdio_uart_write(struct tty_struct *tty, const u8 *buf, int count)
+static ssize_t sdio_uart_write(struct tty_struct *tty, const u8 *buf,
+			      size_t count)
 {
 	struct sdio_uart_port *port = tty->driver_data;
 	int ret;
diff --git a/drivers/net/usb/hso.c b/drivers/net/usb/hso.c
index 014a9d29bab5..3f424da87bf4 100644
--- a/drivers/net/usb/hso.c
+++ b/drivers/net/usb/hso.c
@@ -1322,7 +1322,8 @@ static void hso_serial_close(struct tty_struct *tty, struct file *filp)
 }
 
 /* close the requested serial port */
-static int hso_serial_write(struct tty_struct *tty, const u8 *buf, int count)
+static ssize_t hso_serial_write(struct tty_struct *tty, const u8 *buf,
+				size_t count)
 {
 	struct hso_serial *serial = tty->driver_data;
 	int space, tx_bytes;
diff --git a/drivers/s390/char/con3215.c b/drivers/s390/char/con3215.c
index 8bbce6a4d7f5..99361618c31f 100644
--- a/drivers/s390/char/con3215.c
+++ b/drivers/s390/char/con3215.c
@@ -1021,7 +1021,8 @@ static unsigned int tty3215_write_room(struct tty_struct *tty)
 /*
  * String write routine for 3215 ttys
  */
-static int tty3215_write(struct tty_struct *tty, const u8 *buf, int count)
+static ssize_t tty3215_write(struct tty_struct *tty, const u8 *buf,
+			     size_t count)
 {
 	handle_write(tty->driver_data, buf, count);
 	return count;
diff --git a/drivers/s390/char/con3270.c b/drivers/s390/char/con3270.c
index 6374555a0937..363315fa1666 100644
--- a/drivers/s390/char/con3270.c
+++ b/drivers/s390/char/con3270.c
@@ -1803,7 +1803,8 @@ static void tty3270_do_write(struct tty3270 *tp, struct tty_struct *tty,
 /*
  * String write routine for 3270 ttys
  */
-static int tty3270_write(struct tty_struct *tty, const u8 *buf, int count)
+static ssize_t tty3270_write(struct tty_struct *tty, const u8 *buf,
+			     size_t count)
 {
 	struct tty3270 *tp;
 
diff --git a/drivers/s390/char/sclp_tty.c b/drivers/s390/char/sclp_tty.c
index 831a8c7cacc2..892c18d2f87e 100644
--- a/drivers/s390/char/sclp_tty.c
+++ b/drivers/s390/char/sclp_tty.c
@@ -229,8 +229,8 @@ out:
  * tty device. The characters may come from user space or kernel space. This
  * routine will return the number of characters actually accepted for writing.
  */
-static int
-sclp_tty_write(struct tty_struct *tty, const u8 *buf, int count)
+static ssize_t
+sclp_tty_write(struct tty_struct *tty, const u8 *buf, size_t count)
 {
 	if (sclp_tty_chars_count > 0) {
 		sclp_tty_write_string(sclp_tty_chars, sclp_tty_chars_count, 0);
diff --git a/drivers/s390/char/sclp_vt220.c b/drivers/s390/char/sclp_vt220.c
index e148350c1e2c..218ae604f737 100644
--- a/drivers/s390/char/sclp_vt220.c
+++ b/drivers/s390/char/sclp_vt220.c
@@ -462,8 +462,8 @@ out:
  * user space or kernel space.  This routine will return the
  * number of characters actually accepted for writing.
  */
-static int
-sclp_vt220_write(struct tty_struct *tty, const u8 *buf, int count)
+static ssize_t
+sclp_vt220_write(struct tty_struct *tty, const u8 *buf, size_t count)
 {
 	return __sclp_vt220_write(buf, count, 1, 0, 1);
 }
diff --git a/drivers/staging/gdm724x/gdm_tty.c b/drivers/staging/gdm724x/gdm_tty.c
index ae9978b73d9b..b31f2afb0286 100644
--- a/drivers/staging/gdm724x/gdm_tty.c
+++ b/drivers/staging/gdm724x/gdm_tty.c
@@ -149,7 +149,7 @@ static void gdm_tty_send_complete(void *arg)
 	tty_port_tty_wakeup(&gdm->port);
 }
 
-static int gdm_tty_write(struct tty_struct *tty, const u8 *buf, int len)
+static ssize_t gdm_tty_write(struct tty_struct *tty, const u8 *buf, size_t len)
 {
 	struct gdm *gdm = tty->driver_data;
 	int remain = len;
diff --git a/drivers/staging/greybus/uart.c b/drivers/staging/greybus/uart.c
index 97c7ddd0f53e..999ce613dca8 100644
--- a/drivers/staging/greybus/uart.c
+++ b/drivers/staging/greybus/uart.c
@@ -427,7 +427,7 @@ static void gb_tty_hangup(struct tty_struct *tty)
 	tty_port_hangup(&gb_tty->port);
 }
 
-static int gb_tty_write(struct tty_struct *tty, const u8 *buf, int count)
+static ssize_t gb_tty_write(struct tty_struct *tty, const u8 *buf, size_t count)
 {
 	struct gb_tty *gb_tty = tty->driver_data;
 
diff --git a/drivers/tty/amiserial.c b/drivers/tty/amiserial.c
index 91cf294ec8c1..785558c65ae8 100644
--- a/drivers/tty/amiserial.c
+++ b/drivers/tty/amiserial.c
@@ -741,7 +741,7 @@ static void rs_flush_chars(struct tty_struct *tty)
 	local_irq_restore(flags);
 }
 
-static int rs_write(struct tty_struct * tty, const u8 *buf, int count)
+static ssize_t rs_write(struct tty_struct * tty, const u8 *buf, size_t count)
 {
 	int	c, ret = 0;
 	struct serial_state *info = tty->driver_data;
diff --git a/drivers/tty/ehv_bytechan.c b/drivers/tty/ehv_bytechan.c
index de36347e2145..a067628e01c8 100644
--- a/drivers/tty/ehv_bytechan.c
+++ b/drivers/tty/ehv_bytechan.c
@@ -466,7 +466,8 @@ static irqreturn_t ehv_bc_tty_tx_isr(int irq, void *data)
  * ehv_bc_tty_write_room() will never lie, so the tty layer will never send us
  * too much data.
  */
-static int ehv_bc_tty_write(struct tty_struct *ttys, const u8 *s, int count)
+static ssize_t ehv_bc_tty_write(struct tty_struct *ttys, const u8 *s,
+				size_t count)
 {
 	struct ehv_bc_data *bc = ttys->driver_data;
 	unsigned long flags;
diff --git a/drivers/tty/goldfish.c b/drivers/tty/goldfish.c
index faa597ffbaf9..4591f940b7a1 100644
--- a/drivers/tty/goldfish.c
+++ b/drivers/tty/goldfish.c
@@ -185,7 +185,8 @@ static void goldfish_tty_hangup(struct tty_struct *tty)
 	tty_port_hangup(tty->port);
 }
 
-static int goldfish_tty_write(struct tty_struct *tty, const u8 *buf, int count)
+static ssize_t goldfish_tty_write(struct tty_struct *tty, const u8 *buf,
+				  size_t count)
 {
 	goldfish_tty_do_write(tty->index, buf, count);
 	return count;
diff --git a/drivers/tty/hvc/hvc_console.c b/drivers/tty/hvc/hvc_console.c
index 4c60d15c7a6f..e93e8072ec86 100644
--- a/drivers/tty/hvc/hvc_console.c
+++ b/drivers/tty/hvc/hvc_console.c
@@ -496,7 +496,7 @@ static int hvc_push(struct hvc_struct *hp)
 	return n;
 }
 
-static int hvc_write(struct tty_struct *tty, const u8 *buf, int count)
+static ssize_t hvc_write(struct tty_struct *tty, const u8 *buf, size_t count)
 {
 	struct hvc_struct *hp = tty->driver_data;
 	unsigned long flags;
diff --git a/drivers/tty/hvc/hvcs.c b/drivers/tty/hvc/hvcs.c
index 2465d61b4e76..1de91fa23b04 100644
--- a/drivers/tty/hvc/hvcs.c
+++ b/drivers/tty/hvc/hvcs.c
@@ -1257,7 +1257,7 @@ static void hvcs_hangup(struct tty_struct * tty)
  * tty_hangup will allow hvcs_write time to complete execution before it
  * terminates our device.
  */
-static int hvcs_write(struct tty_struct *tty, const u8 *buf, int count)
+static ssize_t hvcs_write(struct tty_struct *tty, const u8 *buf, size_t count)
 {
 	struct hvcs_struct *hvcsd = tty->driver_data;
 	unsigned int unit_address;
@@ -1299,7 +1299,8 @@ static int hvcs_write(struct tty_struct *tty, const u8 *buf, int count)
 	unit_address = hvcsd->vdev->unit_address;
 
 	while (count > 0) {
-		tosend = min(count, (HVCS_BUFF_LEN - hvcsd->chars_in_buffer));
+		tosend = min_t(unsigned, count,
+			       (HVCS_BUFF_LEN - hvcsd->chars_in_buffer));
 		/*
 		 * No more space, this probably means that the last call to
 		 * hvcs_write() didn't succeed and the buffer was filled up.
diff --git a/drivers/tty/hvc/hvsi.c b/drivers/tty/hvc/hvsi.c
index 46dd62df2442..c57bd85aa488 100644
--- a/drivers/tty/hvc/hvsi.c
+++ b/drivers/tty/hvc/hvsi.c
@@ -904,7 +904,8 @@ static unsigned int hvsi_chars_in_buffer(struct tty_struct *tty)
 	return hp->n_outbuf;
 }
 
-static int hvsi_write(struct tty_struct *tty, const u8 *source, int count)
+static ssize_t hvsi_write(struct tty_struct *tty, const u8 *source,
+			  size_t count)
 {
 	struct hvsi_struct *hp = tty->driver_data;
 	unsigned long flags;
diff --git a/drivers/tty/ipwireless/tty.c b/drivers/tty/ipwireless/tty.c
index cd43208c523c..b6de40815fb9 100644
--- a/drivers/tty/ipwireless/tty.c
+++ b/drivers/tty/ipwireless/tty.c
@@ -186,7 +186,8 @@ static void ipw_write_packet_sent_callback(void *callback_data,
 	tty->tx_bytes_queued -= packet_length;
 }
 
-static int ipw_write(struct tty_struct *linux_tty, const u8 *buf, int count)
+static ssize_t ipw_write(struct tty_struct *linux_tty, const u8 *buf,
+			 size_t count)
 {
 	struct ipw_tty *tty = linux_tty->driver_data;
 	int room, ret;
diff --git a/drivers/tty/mips_ejtag_fdc.c b/drivers/tty/mips_ejtag_fdc.c
index cf4ef0c38624..369ec71c24ef 100644
--- a/drivers/tty/mips_ejtag_fdc.c
+++ b/drivers/tty/mips_ejtag_fdc.c
@@ -796,8 +796,8 @@ static void mips_ejtag_fdc_tty_hangup(struct tty_struct *tty)
 	tty_port_hangup(tty->port);
 }
 
-static int mips_ejtag_fdc_tty_write(struct tty_struct *tty, const u8 *buf,
-				    int total)
+static ssize_t mips_ejtag_fdc_tty_write(struct tty_struct *tty, const u8 *buf,
+					size_t total)
 {
 	int count, block;
 	struct mips_ejtag_fdc_tty_port *dport = tty->driver_data;
@@ -816,7 +816,7 @@ static int mips_ejtag_fdc_tty_write(struct tty_struct *tty, const u8 *buf,
 	 */
 	spin_lock(&dport->xmit_lock);
 	/* Work out how many bytes we can write to the xmit buffer */
-	total = min(total, (int)(priv->xmit_size - dport->xmit_cnt));
+	total = min_t(size_t, total, priv->xmit_size - dport->xmit_cnt);
 	atomic_add(total, &priv->xmit_total);
 	dport->xmit_cnt += total;
 	/* Write the actual bytes (may need splitting if it wraps) */
diff --git a/drivers/tty/moxa.c b/drivers/tty/moxa.c
index d94cf1be651b..bf3f87ba3a92 100644
--- a/drivers/tty/moxa.c
+++ b/drivers/tty/moxa.c
@@ -487,7 +487,7 @@ module_param(ttymajor, int, 0);
  */
 static int moxa_open(struct tty_struct *, struct file *);
 static void moxa_close(struct tty_struct *, struct file *);
-static int moxa_write(struct tty_struct *, const u8 *, int);
+static ssize_t moxa_write(struct tty_struct *, const u8 *, size_t);
 static unsigned int moxa_write_room(struct tty_struct *);
 static void moxa_flush_buffer(struct tty_struct *);
 static unsigned int moxa_chars_in_buffer(struct tty_struct *);
@@ -1499,7 +1499,7 @@ static void moxa_close(struct tty_struct *tty, struct file *filp)
 	tty_port_close(&ch->port, tty, filp);
 }
 
-static int moxa_write(struct tty_struct *tty, const u8 *buf, int count)
+static ssize_t moxa_write(struct tty_struct *tty, const u8 *buf, size_t count)
 {
 	struct moxa_port *ch = tty->driver_data;
 	unsigned long flags;
diff --git a/drivers/tty/mxser.c b/drivers/tty/mxser.c
index a5dfd08d4ea2..10aa4ed38793 100644
--- a/drivers/tty/mxser.c
+++ b/drivers/tty/mxser.c
@@ -901,7 +901,7 @@ static void mxser_close(struct tty_struct *tty, struct file *filp)
 	tty_port_close(tty->port, tty, filp);
 }
 
-static int mxser_write(struct tty_struct *tty, const u8 *buf, int count)
+static ssize_t mxser_write(struct tty_struct *tty, const u8 *buf, size_t count)
 {
 	struct mxser_port *info = tty->driver_data;
 	unsigned long flags;
diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c
index d167e36873fe..3e5cc30941a7 100644
--- a/drivers/tty/n_gsm.c
+++ b/drivers/tty/n_gsm.c
@@ -4256,7 +4256,7 @@ static void gsmtty_hangup(struct tty_struct *tty)
 	gsm_dlci_begin_close(dlci);
 }
 
-static int gsmtty_write(struct tty_struct *tty, const u8 *buf, int len)
+static ssize_t gsmtty_write(struct tty_struct *tty, const u8 *buf, size_t len)
 {
 	int sent;
 	struct gsm_dlci *dlci = tty->driver_data;
diff --git a/drivers/tty/nozomi.c b/drivers/tty/nozomi.c
index b3756402f5d9..02cd40147b3a 100644
--- a/drivers/tty/nozomi.c
+++ b/drivers/tty/nozomi.c
@@ -1599,7 +1599,8 @@ static void ntty_hangup(struct tty_struct *tty)
  * called when the userspace process writes to the tty (/dev/noz*).
  * Data is inserted into a fifo, which is then read and transferred to the modem.
  */
-static int ntty_write(struct tty_struct *tty, const u8 *buffer, int count)
+static ssize_t ntty_write(struct tty_struct *tty, const u8 *buffer,
+			  size_t count)
 {
 	int rval = -EINVAL;
 	struct nozomi *dc = get_dc_by_tty(tty);
diff --git a/drivers/tty/pty.c b/drivers/tty/pty.c
index 335f5744f320..df08f13052ff 100644
--- a/drivers/tty/pty.c
+++ b/drivers/tty/pty.c
@@ -108,7 +108,7 @@ static void pty_unthrottle(struct tty_struct *tty)
  *	the other side of the pty/tty pair.
  */
 
-static int pty_write(struct tty_struct *tty, const u8 *buf, int c)
+static ssize_t pty_write(struct tty_struct *tty, const u8 *buf, size_t c)
 {
 	struct tty_struct *to = tty->link;
 
diff --git a/drivers/tty/rpmsg_tty.c b/drivers/tty/rpmsg_tty.c
index 29db413bbc03..60a2915f5cfe 100644
--- a/drivers/tty/rpmsg_tty.c
+++ b/drivers/tty/rpmsg_tty.c
@@ -73,7 +73,8 @@ static void rpmsg_tty_close(struct tty_struct *tty, struct file *filp)
 	return tty_port_close(tty->port, tty, filp);
 }
 
-static int rpmsg_tty_write(struct tty_struct *tty, const u8 *buf, int len)
+static ssize_t rpmsg_tty_write(struct tty_struct *tty, const u8 *buf,
+			       size_t len)
 {
 	struct rpmsg_tty_port *cport = tty->driver_data;
 	struct rpmsg_device *rpdev;
@@ -86,7 +87,7 @@ static int rpmsg_tty_write(struct tty_struct *tty, const u8 *buf, int len)
 	if (msg_max_size < 0)
 		return msg_max_size;
 
-	msg_size = min(len, msg_max_size);
+	msg_size = min_t(unsigned int, len, msg_max_size);
 
 	/*
 	 * Use rpmsg_trysend instead of rpmsg_send to send the message so the caller is not
diff --git a/drivers/tty/serial/kgdb_nmi.c b/drivers/tty/serial/kgdb_nmi.c
index 2a04d19d5ec0..e93850f6447a 100644
--- a/drivers/tty/serial/kgdb_nmi.c
+++ b/drivers/tty/serial/kgdb_nmi.c
@@ -304,7 +304,8 @@ static unsigned int kgdb_nmi_tty_write_room(struct tty_struct *tty)
 	return 2048;
 }
 
-static int kgdb_nmi_tty_write(struct tty_struct *tty, const u8 *buf, int c)
+static ssize_t kgdb_nmi_tty_write(struct tty_struct *tty, const u8 *buf,
+				  size_t c)
 {
 	int i;
 
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index d5b682ff20b3..7bdc21d5e13b 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -580,7 +580,7 @@ static void uart_flush_chars(struct tty_struct *tty)
 	uart_start(tty);
 }
 
-static int uart_write(struct tty_struct *tty, const u8 *buf, int count)
+static ssize_t uart_write(struct tty_struct *tty, const u8 *buf, size_t count)
 {
 	struct uart_state *state = tty->driver_data;
 	struct uart_port *port;
diff --git a/drivers/tty/synclink_gt.c b/drivers/tty/synclink_gt.c
index 0264e9f7699c..8112d9d5a0d8 100644
--- a/drivers/tty/synclink_gt.c
+++ b/drivers/tty/synclink_gt.c
@@ -745,7 +745,7 @@ static void update_tx_timer(struct slgt_info *info)
 	}
 }
 
-static int write(struct tty_struct *tty, const u8 *buf, int count)
+static ssize_t write(struct tty_struct *tty, const u8 *buf, size_t count)
 {
 	int ret = 0;
 	struct slgt_info *info = tty->driver_data;
@@ -754,7 +754,7 @@ static int write(struct tty_struct *tty, const u8 *buf, int count)
 	if (sanity_check(info, tty->name, "write"))
 		return -EIO;
 
-	DBGINFO(("%s write count=%d\n", info->device_name, count));
+	DBGINFO(("%s write count=%zu\n", info->device_name, count));
 
 	if (!info->tx_buf || (count > info->max_frame_size))
 		return -EIO;
diff --git a/drivers/tty/ttynull.c b/drivers/tty/ttynull.c
index 6b74ebaa0f2d..e4c4273993bc 100644
--- a/drivers/tty/ttynull.c
+++ b/drivers/tty/ttynull.c
@@ -29,7 +29,8 @@ static void ttynull_hangup(struct tty_struct *tty)
 	tty_port_hangup(&ttynull_port);
 }
 
-static int ttynull_write(struct tty_struct *tty, const u8 *buf, int count)
+static ssize_t ttynull_write(struct tty_struct *tty, const u8 *buf,
+			     size_t count)
 {
 	return count;
 }
diff --git a/drivers/tty/vcc.c b/drivers/tty/vcc.c
index c223879039b8..9cc569174c83 100644
--- a/drivers/tty/vcc.c
+++ b/drivers/tty/vcc.c
@@ -804,7 +804,7 @@ static void vcc_hangup(struct tty_struct *tty)
 	tty_port_hangup(tty->port);
 }
 
-static int vcc_write(struct tty_struct *tty, const u8 *buf, int count)
+static ssize_t vcc_write(struct tty_struct *tty, const u8 *buf, size_t count)
 {
 	struct vcc_port *port;
 	struct vio_vcc *pkt;
@@ -826,7 +826,8 @@ static int vcc_write(struct tty_struct *tty, const u8 *buf, int count)
 
 	while (count > 0) {
 		/* Minimum of data to write and space available */
-		tosend = min(count, (VCC_BUFF_LEN - port->chars_in_buffer));
+		tosend = min_t(size_t, count,
+			       (VCC_BUFF_LEN - port->chars_in_buffer));
 
 		if (!tosend)
 			break;
diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c
index ea7c20d66acb..5c47f77804f0 100644
--- a/drivers/tty/vt/vt.c
+++ b/drivers/tty/vt/vt.c
@@ -3238,7 +3238,7 @@ int tioclinux(struct tty_struct *tty, unsigned long arg)
  * /dev/ttyN handling
  */
 
-static int con_write(struct tty_struct *tty, const u8 *buf, int count)
+static ssize_t con_write(struct tty_struct *tty, const u8 *buf, size_t count)
 {
 	int	retval;
 
diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c
index 913b07b30d33..3591880d96bd 100644
--- a/drivers/usb/class/cdc-acm.c
+++ b/drivers/usb/class/cdc-acm.c
@@ -789,7 +789,8 @@ static void acm_tty_close(struct tty_struct *tty, struct file *filp)
 	tty_port_close(&acm->port, tty, filp);
 }
 
-static int acm_tty_write(struct tty_struct *tty, const u8 *buf, int count)
+static ssize_t acm_tty_write(struct tty_struct *tty, const u8 *buf,
+			     size_t count)
 {
 	struct acm *acm = tty->driver_data;
 	int stat;
@@ -800,7 +801,7 @@ static int acm_tty_write(struct tty_struct *tty, const u8 *buf, int count)
 	if (!count)
 		return 0;
 
-	dev_vdbg(&acm->data->dev, "%d bytes from tty layer\n", count);
+	dev_vdbg(&acm->data->dev, "%zu bytes from tty layer\n", count);
 
 	spin_lock_irqsave(&acm->write_lock, flags);
 	wbn = acm_wb_alloc(acm);
@@ -817,7 +818,7 @@ static int acm_tty_write(struct tty_struct *tty, const u8 *buf, int count)
 	}
 
 	count = (count > acm->writesize) ? acm->writesize : count;
-	dev_vdbg(&acm->data->dev, "writing %d bytes\n", count);
+	dev_vdbg(&acm->data->dev, "writing %zu bytes\n", count);
 	memcpy(wb->buf, buf, count);
 	wb->len = count;
 
diff --git a/drivers/usb/gadget/function/u_serial.c b/drivers/usb/gadget/function/u_serial.c
index 3e6b750aa4fc..a92eb6d90976 100644
--- a/drivers/usb/gadget/function/u_serial.c
+++ b/drivers/usb/gadget/function/u_serial.c
@@ -734,12 +734,12 @@ exit:
 	spin_unlock_irq(&port->port_lock);
 }
 
-static int gs_write(struct tty_struct *tty, const u8 *buf, int count)
+static ssize_t gs_write(struct tty_struct *tty, const u8 *buf, size_t count)
 {
 	struct gs_port	*port = tty->driver_data;
 	unsigned long	flags;
 
-	pr_vdebug("gs_write: ttyGS%d (%p) writing %d bytes\n",
+	pr_vdebug("gs_write: ttyGS%d (%p) writing %zu bytes\n",
 			port->port_num, tty, count);
 
 	spin_lock_irqsave(&port->port_lock, flags);
diff --git a/drivers/usb/host/xhci-dbgtty.c b/drivers/usb/host/xhci-dbgtty.c
index 5b82bdd82ba9..b74e98e94393 100644
--- a/drivers/usb/host/xhci-dbgtty.c
+++ b/drivers/usb/host/xhci-dbgtty.c
@@ -208,7 +208,8 @@ static void dbc_tty_close(struct tty_struct *tty, struct file *file)
 	tty_port_close(&port->port, tty, file);
 }
 
-static int dbc_tty_write(struct tty_struct *tty, const u8 *buf, int count)
+static ssize_t dbc_tty_write(struct tty_struct *tty, const u8 *buf,
+			     size_t count)
 {
 	struct dbc_port		*port = tty->driver_data;
 	unsigned long		flags;
diff --git a/drivers/usb/serial/usb-serial.c b/drivers/usb/serial/usb-serial.c
index 51f738ea3f77..17b09f03ef84 100644
--- a/drivers/usb/serial/usb-serial.c
+++ b/drivers/usb/serial/usb-serial.c
@@ -361,7 +361,7 @@ static void serial_cleanup(struct tty_struct *tty)
 	module_put(owner);
 }
 
-static int serial_write(struct tty_struct *tty, const u8 *buf, int count)
+static ssize_t serial_write(struct tty_struct *tty, const u8 *buf, size_t count)
 {
 	struct usb_serial_port *port = tty->driver_data;
 	int retval = -ENODEV;
@@ -369,7 +369,7 @@ static int serial_write(struct tty_struct *tty, const u8 *buf, int count)
 	if (port->serial->dev->state == USB_STATE_NOTATTACHED)
 		goto exit;
 
-	dev_dbg(&port->dev, "%s - %d byte(s)\n", __func__, count);
+	dev_dbg(&port->dev, "%s - %zu byte(s)\n", __func__, count);
 
 	retval = port->serial->type->write(tty, port, buf, count);
 	if (retval < 0)
diff --git a/include/linux/tty_driver.h b/include/linux/tty_driver.h
index c5299d952e59..18beff0cec1a 100644
--- a/include/linux/tty_driver.h
+++ b/include/linux/tty_driver.h
@@ -72,8 +72,8 @@ struct serial_struct;
  *	is closed for the last time freeing up the resources. This is
  *	actually the second part of shutdown for routines that might sleep.
  *
- * @write: ``int ()(struct tty_struct *tty, const unsigned char *buf,
- *		    int count)``
+ * @write: ``ssize_t ()(struct tty_struct *tty, const unsigned char *buf,
+ *		    size_t count)``
  *
  *	This routine is called by the kernel to write a series (@count) of
  *	characters (@buf) to the @tty device. The characters may come from
@@ -356,7 +356,7 @@ struct tty_operations {
 	void (*close)(struct tty_struct * tty, struct file * filp);
 	void (*shutdown)(struct tty_struct *tty);
 	void (*cleanup)(struct tty_struct *tty);
-	int  (*write)(struct tty_struct *tty, const u8 *buf, int count);
+	ssize_t (*write)(struct tty_struct *tty, const u8 *buf, size_t count);
 	int  (*put_char)(struct tty_struct *tty, u8 ch);
 	void (*flush_chars)(struct tty_struct *tty);
 	unsigned int (*write_room)(struct tty_struct *tty);
diff --git a/net/bluetooth/rfcomm/tty.c b/net/bluetooth/rfcomm/tty.c
index 3b5f8404dc84..33b135ed59c4 100644
--- a/net/bluetooth/rfcomm/tty.c
+++ b/net/bluetooth/rfcomm/tty.c
@@ -779,14 +779,15 @@ static void rfcomm_tty_close(struct tty_struct *tty, struct file *filp)
 	tty_port_close(&dev->port, tty, filp);
 }
 
-static int rfcomm_tty_write(struct tty_struct *tty, const u8 *buf, int count)
+static ssize_t rfcomm_tty_write(struct tty_struct *tty, const u8 *buf,
+				size_t count)
 {
 	struct rfcomm_dev *dev = tty->driver_data;
 	struct rfcomm_dlc *dlc = dev->dlc;
 	struct sk_buff *skb;
 	int sent = 0, size;
 
-	BT_DBG("tty %p count %d", tty, count);
+	BT_DBG("tty %p count %zu", tty, count);
 
 	while (count) {
 		size = min_t(uint, count, dlc->mtu);