TTY: switch tty_flip_buffer_push

Now, we start converting tty buffer functions to actually use
tty_port. This will allow us to get rid of the need of tty in many
call sites. Only tty_port will needed and hence no more
tty_port_tty_get in those paths.

Now, the one where most of tty_port_tty_get gets removed:
tty_flip_buffer_push.

IOW we also closed all the races in drivers not using tty_port_tty_get
at all yet.

Also we move tty_flip_buffer_push declaration from include/linux/tty.h
to include/linux/tty_flip.h to all others while we are changing it
anyway.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 15 insertions, 26 deletions

diff --git a/drivers/staging/fwserial/fwserial.c b/drivers/staging/fwserial/fwserial.c
index a2a0c43dec1..b403393c49c 100644
--- a/drivers/staging/fwserial/fwserial.c
+++ b/drivers/staging/fwserial/fwserial.c
@@ -489,16 +489,11 @@ static void fwtty_do_hangup(struct work_struct *work)
 static void fwtty_emit_breaks(struct work_struct *work)
 {
 	struct fwtty_port *port = to_port(to_delayed_work(work), emit_breaks);
-	struct tty_struct *tty;
 	static const char buf[16];
 	unsigned long now = jiffies;
 	unsigned long elapsed = now - port->break_last;
 	int n, t, c, brk = 0;
 
-	tty = tty_port_tty_get(&port->port);
-	if (!tty)
-		return;
-
 	/* generate breaks at the line rate (but at least 1) */
 	n = (elapsed * port->cps) / HZ + 1;
 	port->break_last = now;
@@ -514,9 +509,7 @@ static void fwtty_emit_breaks(struct work_struct *work)
 		if (c < t)
 			break;
 	}
-	tty_flip_buffer_push(tty);
-
-	tty_kref_put(tty);
+	tty_flip_buffer_push(&port->port);
 
 	if (port->mstatus & (UART_LSR_BI << 24))
 		schedule_delayed_work(&port->emit_breaks, FREQ_BREAKS);
@@ -530,10 +523,6 @@ static void fwtty_pushrx(struct work_struct *work)
 	struct buffered_rx *buf, *next;
 	int n, c = 0;
 
-	tty = tty_port_tty_get(&port->port);
-	if (!tty)
-		return;
-
 	spin_lock_bh(&port->lock);
 	list_for_each_entry_safe(buf, next, &port->buf_list, list) {
 		n = tty_insert_flip_string_fixed_flag(&port->port, buf->data,
@@ -545,7 +534,11 @@ static void fwtty_pushrx(struct work_struct *work)
 				memmove(buf->data, buf->data + n, buf->n - n);
 				buf->n -= n;
 			}
-			__fwtty_throttle(port, tty);
+			tty = tty_port_tty_get(&port->port);
+			if (tty) {
+				__fwtty_throttle(port, tty);
+				tty_kref_put(tty);
+			}
 			break;
 		} else {
 			list_del(&buf->list);
@@ -553,13 +546,11 @@ static void fwtty_pushrx(struct work_struct *work)
 		}
 	}
 	if (c > 0)
-		tty_flip_buffer_push(tty);
+		tty_flip_buffer_push(&port->port);
 
 	if (list_empty(&port->buf_list))
 		clear_bit(BUFFERING_RX, &port->flags);
 	spin_unlock_bh(&port->lock);
-
-	tty_kref_put(tty);
 }
 
 static int fwtty_buffer_rx(struct fwtty_port *port, unsigned char *d, size_t n)
@@ -594,10 +585,6 @@ static int fwtty_rx(struct fwtty_port *port, unsigned char *data, size_t len)
 	unsigned lsr;
 	int err = 0;
 
-	tty = tty_port_tty_get(&port->port);
-	if (!tty)
-		return -ENOENT;
-
 	fwtty_dbg(port, "%d", n);
 	profile_size_distrib(port->stats.reads, n);
 
@@ -634,16 +621,20 @@ static int fwtty_rx(struct fwtty_port *port, unsigned char *data, size_t len)
 		c = tty_insert_flip_string_fixed_flag(&port->port, data,
 				TTY_NORMAL, n);
 		if (c > 0)
-			tty_flip_buffer_push(tty);
+			tty_flip_buffer_push(&port->port);
 		n -= c;
 
 		if (n) {
 			/* start buffering and throttling */
 			n -= fwtty_buffer_rx(port, &data[c], n);
 
-			spin_lock_bh(&port->lock);
-			__fwtty_throttle(port, tty);
-			spin_unlock_bh(&port->lock);
+			tty = tty_port_tty_get(&port->port);
+			if (tty) {
+				spin_lock_bh(&port->lock);
+				__fwtty_throttle(port, tty);
+				spin_unlock_bh(&port->lock);
+				tty_kref_put(tty);
+			}
 		}
 	} else
 		n -= fwtty_buffer_rx(port, data, n);
@@ -654,8 +645,6 @@ static int fwtty_rx(struct fwtty_port *port, unsigned char *data, size_t len)
 	}
 
 out:
-	tty_kref_put(tty);
-
 	port->icount.rx += len;
 	port->stats.lost += n;
 	return err;