linux-kernel - Re: n_tty_write() going into schedule but NOT coming out

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Date:	Fri, 05 Apr 2013 15:52:47 -0400
From:	Peter Hurley <peter@...leysoftware.com>
To:	Vineet Gupta <Vineet.Gupta1@...opsys.com>
Cc:	lkml <linux-kernel@...r.kernel.org>, linux-serial@...r.kernel.org,
	Jiri Slaby <jslaby@...e.cz>
Subject: Re: n_tty_write() going into schedule but NOT coming out

[ --cc Ingo and Peter Z. as this is not scheduler-related]

On Tue, 2013-04-02 at 18:56 +0530, Vineet Gupta wrote:
> On 04/01/2013 08:40 PM, Peter Hurley wrote:
> > On Mon, 2013-04-01 at 19:27 +0530, Vineet Gupta wrote:
> >> Hi,
> >>
> >> Any thoughts: I observe the same issue even with CONFIG_PREEMPT and
> >> CONFIG_PREEMPT_COUNT

I'll see if I can reproduce this over the weekend on an old single-core
laptop I still have.

There were some race conditions in the N_TTY line discipline which I
recently fixed. Those changes are in linux-next. Can you test if this is
reproducible on linux-next?

Assuming I don't reproduce this on the laptop, the only other
explanation I can think of right now is that ARCLinux is not properly
handling signal-driven i/o (assuming the BusyBox /bin/sh uses SIGIO). Do
you know if there is anything special about the way ARCLinux handle
signals?

Regards,
Peter Hurley

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