Message-ID: <47A8C4AB.3030301@microgate.com>
Date: Tue, 05 Feb 2008 14:18:51 -0600
From: Paul Fulghum <paulkf@microgate.com>
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To: Rick Warner <rick@microway.com>
CC: linux-kernel@vger.kernel.org
Subject: Re: serial port regression caused by "Char: tty_ioctl, use wait_event_interruptible_timeout"
 patch
References: <200802051402.26816.rick@microway.com>
In-Reply-To: <200802051402.26816.rick@microway.com>
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Rick Warner wrote:
> I narrowed down the problem doing a binary search on git snapshots between .22 
> and .23, and found the breakage between git6 and git7.  Further isolating it 
> found the patch mentioned in the subject to be the cause.  I reversed the 
> patch in the .23 source and it now works properly.
> 
> Should the code be reverted back as I did, or is there something I should 
> change in our userspace code that reads from the serial port to correct it 
> instead?

Instead of reverting the patch can you try modifying
this part of the patch:

+	if (wait_event_interruptible_timeout(tty->write_wait,
+			!tty->driver->chars_in_buffer(tty), timeout))
+		return;

by changing it to:

+	if (wait_event_interruptible_timeout(tty->write_wait,
+			!tty->driver->chars_in_buffer(tty), timeout) < 0)
+		return;

It looks like the patch changed the behavior of
tty_wait_until_sent by not calling the driver
specific wait_until_sent if a timeout occurs.

-- 
Paul Fulghum
Microgate Systems, Ltd.
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