linux-kernel - [PATCH]tty: Incorrect use tty_ldisc

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Message-ID: <50B4041C.9030002@ilyx.ru>
Date:	Tue, 27 Nov 2012 04:06:52 +0400
From:	Ilya Zykov <ilya@...x.ru>
To:	Alan Cox <alan@...ux.intel.com>
CC:	Andrew McGregor <andrew.mcgregor@...iedtelesis.co.nz>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	linux-serial@...r.kernel.org, linux-kernel@...r.kernel.org,
	ilya@...x.ru
Subject: [PATCH]tty: Incorrect use tty_ldisc_flush() in TTY drivers.

Sorry. Correct patch format.

Related bug 'tty: fix "IRQ45: nobody cared"'
Related commit 7b292b4bf9a9d6098440d85616d6ca4c608b8304

  Unfortunately, some drivers indirectly call ldisc's flush_buffer() function 
in own callback function close(). In particularly, by the use of tty_ldisc_flush(),
before TTY LAYER calls ldisc's flush_buffer() in the right moment.

1. It disturb the logic of work ldisc's layer.
2. It is simple overhead because we call ldisc's flush_buffer() at least two times.

Please, tell me what do you think about this? Can I make the adjustment for other drivers?

Signed-off-by: Ilya Zykov <ilya@...x.ru>
---
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index 0fcfd98..d87f353 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -1304,7 +1304,7 @@ static void uart_close(struct tty_struct *tty, struct file *filp)
 	uart_shutdown(tty, state);
 	uart_flush_buffer(tty);
 
-	tty_ldisc_flush(tty);
+	tty_buffer_flush(tty);
 
 	tty_port_tty_set(port, NULL);
 	spin_lock_irqsave(&port->lock, flags);
diff --git a/drivers/tty/tty_port.c b/drivers/tty/tty_port.c
index d7bdd8d..8a02996 100644
--- a/drivers/tty/tty_port.c
+++ b/drivers/tty/tty_port.c
@@ -428,8 +428,8 @@ int tty_port_close_start(struct tty_port *port,
 			timeout = 2 * HZ;
 		schedule_timeout_interruptible(timeout);
 	}
-	/* Flush the ldisc buffering */
-	tty_ldisc_flush(tty);
+	/* Flush the driver buffering */
+	tty_buffer_flush(tty);
 
 	/* Drop DTR/RTS if HUPCL is set. This causes any attached modem to
 	   hang up the line */
--
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