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Date: Mon, 16 Aug 2021 09:17:30 +0200 (CEST)
From: Jiri Kosina <jikos@kernel.org>
To: Denis Efremov <efremov@linux.com>
cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, 
    regressions@lists.linux.dev, Mark Hounschell <markh@compro.net>, 
    Wim Osterholt <wim@djo.tudelft.nl>, Kurt Garloff <kurt@garloff.de>, 
    stable@vger.kernel.org
Subject: Re: [PATCH] Revert "floppy: reintroduce O_NDELAY fix"
In-Reply-To: <20210808074246.33449-1-efremov@linux.com>
Message-ID: <nycvar.YFH.7.76.2108160914070.8253@cbobk.fhfr.pm>
References: <de10cb47-34d1-5a88-7751-225ca380f735@compro.net> <20210808074246.33449-1-efremov@linux.com>
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On Sun, 8 Aug 2021, Denis Efremov wrote:

> The patch breaks userspace implementations (e.g. fdutils) and introduces
> regressions in behaviour. Previously, it was possible to O_NDELAY open a
> floppy device with no media inserted or with write protected media without
> an error. Some userspace tools use this particular behavior for probing.
> 
> It's not the first time when we revert this patch. Previous revert is in
> commit f2791e7eadf4 (Revert "floppy: refactor open() flags handling").
> 
> This reverts commit 8a0c014cd20516ade9654fc13b51345ec58e7be8.

By reverting it you bring back the bugs that were fixed by it -- e.g. the 
possibility to livelock mmap() on the returned fd to keep waiting on the 
page unlock bit forever, or the functionality bug reported at [1], and 
likely others.

[1] https://bugzilla.suse.com/show_bug.cgi?id=1181018

-- 
Jiri Kosina
SUSE Labs