Re: [REGRESSION] "USB: use kfifo to buffer usb-generic serial writes" causes gobi_loader to hang

[Oliver Neukum]

Am Montag, 18. Januar 2010 21:14:16 schrieb Matthew Garrett:

> drivers/usb/serial/generic.c: usb_serial_generic_write - port 0, 1565 
> bytes
> drivers/usb/serial/generic.c: usb_serial_generic_write - put 0 bytes 
> into fifo
> drivers/usb/serial/generic.c: usb_serial_generic_read_bulk_callback - 
> port 0

If the FIFO is full we can do nothing. Please try the attached patch.

	Regards
		Oliver
From d7317bae0772b794a1cc9b832bc3d3e1b3642a13 Mon Sep 17 00:00:00 2001
From: Oliver Neukum <oliver@xxxxxxxxxx>
Date: Tue, 19 Jan 2010 14:16:41 +0100
Subject: [PATCH] usb:serial:Deal with filled FIFO

Bail out if the FIFO is filled

Signed-off-by: Oliver Neukum <oliver@xxxxxxxxxx>
---
 drivers/usb/serial/generic.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/drivers/usb/serial/generic.c b/drivers/usb/serial/generic.c
index 76e5514..053f7f1 100644
--- a/drivers/usb/serial/generic.c
+++ b/drivers/usb/serial/generic.c
@@ -349,6 +349,10 @@ int usb_serial_generic_write(struct tty_struct *tty,
 
 	count = kfifo_in_locked(&port->write_fifo, buf, count, &port->lock);
 	dbg("%s - put %d bytes into fifo", __func__, count);
+	if (!count) {
+		dbg("%s - FIFO is full", __func__);
+		return 0;
+	}
 	result = usb_serial_generic_write_start(port);
 
 	if (result >= 0)
-- 
1.6.4.2