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Date: Sun, 9 Jul 2017 20:08:14 +0100
From: Okash Khawaja <okash.khawaja@gmail.com>
To: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Jiri Slaby <jslaby@suse.com>,
        Samuel Thibault <samuel.thibault@ens-lyon.org>,
        Alan Cox <gnomes@lxorguk.ukuu.org.uk>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        William Hubbs <w.d.hubbs@gmail.com>,
        Chris Brannon <chris@the-brannons.com>, Kirk Reiser <kirk@reisers.ca>,
        speakup@linux-speakup.org, devel@driverdev.osuosl.org
Subject: Re: [patch 1/3] tty: resolve tty contention between kernel and user
 space
Message-ID: <20170709190814.GA913@sanghar>
References: <20170708083803.GA23080@kroah.com>
 <20170709114153.157783481@gmail.com>
 <20170709114426.618570903@gmail.com>
 <CAHp75VdwWNj8PHRAMLqcQKhtT=sS5-n9T3n8GY1Rte=MKOQV-w@mail.gmail.com>
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Hi,

On Sun, Jul 09, 2017 at 06:04:17PM +0300, Andy Shevchenko wrote:
 
> Above
> 1. take mutex
> 2. take reference
> 
> Here:
> 1. give mutex back
> 2. give reference back
> 
> I think we usually see symmetrical  calls, i.e.
> 
> 1. give reference back
> 2. give mutex back
> 
> So, what did I miss?

After we hold the kref, driver won't disappear from underneath us so we
don't need tty_mutex just for decrementing the refcount.

Thanks,
Okash