Message-ID: <47A8CCC0.8020703@microgate.com>
Date: Tue, 05 Feb 2008 14:53:20 -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> <47A8C4AB.3030301@microgate.com>
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Paul Fulghum wrote:
> 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.

I mispoke, the patch changed the behavior by not
calling the driver specific wait_until_sent if
the condition is true.

Original behavior:
call driver->wait_until_sent() on
timeout or true condition
(skip for signal)

Patch behavior:
call driver->wait_until_sent() only
on timeout (rc == 0)
(skip for signal or true)

By modifying the patch as described above,
the original behavior is restored.

-- 
Paul Fulghum
Microgate Systems, Ltd.
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