linux-kernel - Re: [RFC/RFT 01/10] i2c: add 'is_suspended' flag for i2c adapters

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Message-ID: <CAMuHMdWH-bh=cfZhxrD6MYfqFUYroai5WbyYZ6+H4MQeubN=PA@mail.gmail.com>
Date:   Wed, 19 Dec 2018 10:39:05 +0100
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Wolfram Sang <wsa@...-dreams.de>
Cc:     Peter Rosin <peda@...ntia.se>, Hans de Goede <hdegoede@...hat.com>,
        "linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-renesas-soc@...r.kernel.org" 
        <linux-renesas-soc@...r.kernel.org>,
        Wolfram Sang <wsa+renesas@...g-engineering.com>,
        "linux-i2c@...r.kernel.org" <linux-i2c@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [RFC/RFT 01/10] i2c: add 'is_suspended' flag for i2c adapters

Hi Wolfram,

On Wed, Dec 19, 2018 at 12:34 AM Wolfram Sang <wsa@...-dreams.de> wrote:
> > > +   unsigned int is_suspended:1;    /* owned by the I2C core */
> >
> > When more stuff is added to this bit field (which always happens at
> > some point) updates to all members of the bit field will have to use
> > the same root-adapter-locking, or we will suffer from RMW-races. So
> > this feels like an invitation for future disaster. Maybe a comment
> > about that to remind our future selves? Or perhaps the bit field
> > should be avoided altogether?
>
> Changed to bool. Thanks!

Does that help, given bool is smaller than the CPUs word size?
Is it Alpha that cannot do atomic operations on bytes?

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds