Re: Linux 2.4.28-rc1

[Paul Fulghum <paulkf@microgate.com>]

On Fri, 2004-10-22 at 13:59, Marcelo Tosatti wrote:
> Here goes the first release candidate of v2.4.28.

Any chance of getting this in?

-- 
Paul Fulghum
paulkf@microgate.com

>From paulkf@microgate.com Fri Oct  8 13:20:56 2004
Subject: [PATCH] serial receive lockup fix
From: Paul Fulghum <paulkf@microgate.com>
To: Marcelo Tosatti <marcelo.tosatti@cyclades.com>
Cc: linux-kernel <linux-kernel@vger.kernel.org>

Fix lockup caused by serial driver not clearing
receive interrupt if flip buffer becomes full.

Signed-off-by: Paul Fulghum <paulkf@microgate.com>



--- a/drivers/char/serial.c	2004-09-29 09:08:35.000000000 -0500
+++ b/drivers/char/serial.c	2004-09-29 09:09:07.000000000 -0500
@@ -573,8 +573,19 @@
 	do {
 		if (tty->flip.count >= TTY_FLIPBUF_SIZE) {
 			tty->flip.tqueue.routine((void *) tty);
-			if (tty->flip.count >= TTY_FLIPBUF_SIZE)
+			if (tty->flip.count >= TTY_FLIPBUF_SIZE) {
+				/* no room in flip buffer, discard rx FIFO contents to clear IRQ
+				 * *FIXME* Hardware with auto flow control
+				 * would benefit from leaving the data in the FIFO and
+				 * disabling the rx IRQ until space becomes available.
+				 */
+				do {
+					serial_inp(info, UART_RX);
+					icount->overrun++;
+					*status = serial_inp(info, UART_LSR);
+				} while ((*status & UART_LSR_DR) && (max_count-- > 0));
 				return;		// if TTY_DONT_FLIP is set
+			}
 		}
 		ch = serial_inp(info, UART_RX);
 		*tty->flip.char_buf_ptr = ch;