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Date:   Wed, 23 Sep 2020 18:57:45 +0200
From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     Maximilian Luz <luzmaximilian@gmail.com>
Cc:     linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org,
        Arnd Bergmann <arnd@arndb.de>, Rob Herring <robh@kernel.org>,
        Jiri Slaby <jirislaby@kernel.org>,
        =?utf-8?B?Qmxhxb4=?= Hrastnik <blaz@mxxn.io>,
        Dorian Stoll <dorian.stoll@tmsp.io>
Subject: Re: [RFC PATCH 1/9] misc: Add Surface Aggregator subsystem
Message-ID: <20200923165745.GA3732240@kroah.com>
References: <20200923151511.3842150-1-luzmaximilian@gmail.com>
 <20200923151511.3842150-2-luzmaximilian@gmail.com>
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On Wed, Sep 23, 2020 at 05:15:03PM +0200, Maximilian Luz wrote:
> +/* -- Safe counters. -------------------------------------------------------- */
> +
> +/**
> + * ssh_seq_reset() - Reset/initialize sequence ID counter.
> + * @c: The counter to reset.
> + */
> +static void ssh_seq_reset(struct ssh_seq_counter *c)
> +{
> +	WRITE_ONCE(c->value, 0);
> +}

These "counters" are odd, what exactly are they?

They seem like a simple atomic counter, but not quite, so you have
rolled your own pseudo-atomic variable.  Are you sure that it works
properly?  If so, how?

What about just using an ida/idr structure instead?  Or just a simple
atomic counter that avoids the values you can't touch, or better yet, a
simple number with a correct lock protecting it :)

thanks,

greg k-h