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Date:   Thu, 23 Jul 2020 15:11:58 -0700 (PDT)
Message-Id: <20200723.151158.2190104866687627036.davem@davemloft.net>
To:     madhuparnabhowmik10@gmail.com
Cc:     isdn@linux-pingi.de, arnd@arndb.de, gregkh@linuxfoundation.org,
        edumazet@google.com, netdev@vger.kernel.org,
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        ldv-project@linuxtesting.org
Subject: Re: [PATCH] drivers: isdn: capi: Fix data-race bug
From:   David Miller <davem@davemloft.net>
In-Reply-To: <20200722172329.16727-1-madhuparnabhowmik10@gmail.com>
References: <20200722172329.16727-1-madhuparnabhowmik10@gmail.com>
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From: madhuparnabhowmik10@gmail.com
Date: Wed, 22 Jul 2020 22:53:29 +0530

> From: Madhuparna Bhowmik <madhuparnabhowmik10@gmail.com>
> 
> In capi_init(), after register_chrdev() the file operation callbacks
> can be called. However capinc_tty_init() is called later.
> Since capiminors and capinc_tty_driver are initialized in
> capinc_tty_init(), their initialization can race with their usage
> in various callbacks like in capi_release().
> 
> Therefore, call capinc_tty_init() before register_chrdev to avoid
> such race conditions.
> 
> Found by Linux Driver Verification project (linuxtesting.org).
> 
> Signed-off-by: Madhuparna Bhowmik <madhuparnabhowmik10@gmail.com>

I agree with Arnd that this just exchanges one set of problems for
another.