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Date: Thu, 21 Dec 2023 09:10:48 +0100
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: Ahelenia =?utf-8?Q?Ziemia=C5=84ska?= <nabijaczleweli@nabijaczleweli.xyz>
Cc: Jens Axboe <axboe@kernel.dk>, Christian Brauner <brauner@kernel.org>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	linux-fsdevel@vger.kernel.org, Jiri Slaby <jirislaby@kernel.org>,
	linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org
Subject: Re: [PATCH v2 08/11] tty: splice_read: disable
Message-ID: <2023122141-footboard-yam-433c@gregkh>
References: <cover.1703126594.git.nabijaczleweli@nabijaczleweli.xyz>
 <4dec932dcd027aa5836d70a6d6bedd55914c84c2.1703126594.git.nabijaczleweli@nabijaczleweli.xyz>
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In-Reply-To: <4dec932dcd027aa5836d70a6d6bedd55914c84c2.1703126594.git.nabijaczleweli@nabijaczleweli.xyz>

On Thu, Dec 21, 2023 at 04:09:10AM +0100, Ahelenia Ziemiańska wrote:
> We request non-blocking I/O in the generic copy_splice_read, but
> "the tty layer doesn't actually honor the IOCB_NOWAIT flag for
> various historical reasons.". This means that a tty->pipe splice
> will happily sleep with the pipe locked forever, and any process
> trying to take it (due to an open/read/write/&c.) will enter
> uninterruptible sleep.
> 
> This also masks inconsistent wake-ups (usually every second line)
> when splicing from ttys in icanon mode.
> 
> Link: https://lore.kernel.org/linux-fsdevel/CAHk-=wimmqG_wvSRtMiKPeGGDL816n65u=Mq2+H3-=uM2U6FmA@mail.gmail.com/
> Signed-off-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz>
> ---

Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>