linux-kernel - Re: pty FIONREAD returning zero breaks emacs in 3.11rc3

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Date:	Mon, 12 Aug 2013 21:43:43 -0400
From:	Peter Hurley <peter@...leysoftware.com>
To:	Andi Kleen <andi@...stfloor.org>
CC:	linux-kernel@...r.kernel.org, gregkh@...uxfoundation.org,
	viro@...iv.linux.org.uk
Subject: Re: pty FIONREAD returning zero breaks emacs in 3.11rc3

On 08/09/2013 05:11 PM, Andi Kleen wrote:
>
> When I run emacs over ssh terminal (no X) on 3.11-rc3 it often ignores key
> strokes.  I first thought the system was busy or so, but when
> stracing the emacs it was not blocked.

Andi,

More information might help me narrow this down since I can't
reproduce this.

Is the ssh session remote?
Can you reproduce this on a local ssh session?
What version of emacs is this? Is it the nox flavor?
What distribution/version?
What platform?

> Here's a typical sequence. select/SIGIO wakes it up, but then
> FIONREAD returns 0.
>
> I'm not fully sure when it started.

In the 3.11 cycle? or could have started back on 3.9 or earlier?

Could you try to reproduce this on linux-next?

> It does not happen all the time, but is quite frequent.
>
> ioctl(3, FIONREAD, [0])                 = 0
> pselect6(4, [3], [], NULL, {17, 952336932}, {NULL, 8}) = 1 (in [3], left
> {17, 504942810})
> --- SIGIO {si_signo=SIGIO, si_code=SI_KERNEL} ---
> rt_sigreturn()                          = 1
> ioctl(3, FIONREAD, [0])                 = 0
> ioctl(3, FIONREAD, [0])                 = 0
> pselect6(4, [3], [], NULL, {17, 504298807}, {NULL, 8}) = ?
> ERESTARTNOHAND (Interrupted by signal)
> --- SIGIO {si_signo=SIGIO, si_code=SI_KERNEL} ---
> rt_sigreturn()                          = -1 EINTR (Interrupted system
> call)
> ioctl(3, FIONREAD, [0])                 = 0
> pselect6(4, [3], [], NULL, {17, 103972440}, {NULL, 8}) = 1 (in [3], left
> {16, 864890560})
> --- SIGIO {si_signo=SIGIO, si_code=SI_KERNEL} ---
> rt_sigreturn()                          = 1

Would you please attach the full strace of emacs from this session?

Regards,
Peter Hurley
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