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Date:   Thu, 21 Jan 2021 16:05:52 +0100 (CET)
From:   Jiri Kosina <jikos@kernel.org>
To:     Denis Efremov <efremov@linux.com>
cc:     Jens Axboe <axboe@kernel.dk>, linux-kernel@vger.kernel.org,
        linux-block@vger.kernel.org, Wim Osterholt <wim@djo.tudelft.nl>
Subject: Re: [PATCH RESEND] floppy: fix open(O_ACCMODE) for ioctl-only open
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On Thu, 21 Jan 2021, Denis Efremov wrote:

> > From: Jiri Kosina <jkosina@suse.cz>
> > Subject: [PATCH v2] floppy: reintroduce O_NDELAY fix
> > 
> > Originally fixed in 09954bad4 ("floppy: refactor open() flags handling")
> > then reverted for unknown reason in f2791e7eadf437 instead of taking
> > the open(O_ACCMODE) for ioctl-only open fix, which had the changelog below
> > 
> > ====
> > Commit 09954bad4 ("floppy: refactor open() flags handling"), as a
> > side-effect, causes open(/dev/fdX, O_ACCMODE) to fail. It turns out that
> > this is being used setfdprm userspace for ioctl-only open().
> > 
> > Reintroduce back the original behavior wrt !(FMODE_READ|FMODE_WRITE)
> > modes, while still keeping the original O_NDELAY bug fixed.
> > 
> > Cc: stable@vger.kernel.org # v4.5+
> 
> Are you sure that it's not worth to backport it to LTS v4.4? Because 
> f2791e7ead is just a revert and 09954bad4 is not presented in v4.4 I'm 
> not sure what fixes tag is better to use in this case.

You are right; I'll drop the '4.5+' indicator and will backport it once/if 
it hits Linus' tree.

> > +	if (mode & (FMODE_READ|FMODE_WRITE)) {
> > +		UDRS->last_checked = 0;
> 
> UDRS will still break the compilation here.

Doh, forgot to refresh before sending, sorry for the noise.
I'll send the final version once I get confirmation from the reporter that 
it's fixing the issue properly, add his Reported-by: etc.

Thanks,

-- 
Jiri Kosina
SUSE Labs