linux-kernel - Re: [PATCH] Revert "floppy: reintroduce O

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Date:   Mon, 16 Aug 2021 09:17:30 +0200 (CEST)
From:   Jiri Kosina <jikos@...nel.org>
To:     Denis Efremov <efremov@...ux.com>
cc:     linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
        regressions@...ts.linux.dev, Mark Hounschell <markh@...pro.net>,
        Wim Osterholt <wim@....tudelft.nl>,
        Kurt Garloff <kurt@...loff.de>, stable@...r.kernel.org
Subject: Re: [PATCH] Revert "floppy: reintroduce O_NDELAY fix"

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