linux-kernel - Re: [PATCH v2 7/8] thunderbolt: Add support for Intel Ice Lake

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Message-ID: <20190813161038.tip2u2z22xqnmfjl@wunner.de>
Date:   Tue, 13 Aug 2019 18:10:38 +0200
From:   Lukas Wunner <lukas@...ner.de>
To:     Mika Westerberg <mika.westerberg@...ux.intel.com>
Cc:     linux-kernel@...r.kernel.org,
        Andreas Noever <andreas.noever@...il.com>,
        Michael Jamet <michael.jamet@...el.com>,
        Yehezkel Bernat <YehezkelShB@...il.com>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Len Brown <lenb@...nel.org>, Mario.Limonciello@...l.com,
        Anthony Wong <anthony.wong@...onical.com>,
        Rajmohan Mani <rajmohan.mani@...el.com>,
        Raanan Avargil <raanan.avargil@...el.com>,
        David Laight <David.Laight@...LAB.COM>,
        linux-acpi@...r.kernel.org
Subject: Re: [PATCH v2 7/8] thunderbolt: Add support for Intel Ice Lake

On Mon, Aug 12, 2019 at 03:38:46PM +0300, Mika Westerberg wrote:
> +static void icm_veto_begin(struct tb *tb)
> +{
> +	struct icm *icm = tb_priv(tb);
> +
> +	if (!icm->veto) {
> +		icm->veto = true;
> +		/* Keep the domain powered while veto is in effect */
> +		pm_runtime_get(&tb->dev);
> +	}
> +}

Hm, don't you need memory barriers when accessing icm->veto?

If so, I'd suggest:

	/* Keep the domain powered while veto is in effect */
	if (cmpxchg(&icm->veto, false, true))
		pm_runtime_get(&tb->dev);

You'll have to declare icm->veto unsigned int instead of bool
because thunderbolt.ko is compiled if CONFIG_COMPILE_TEST is
enabled and there are arches which do not support cmpxchg for
a size of 1 byte.

The other bools in struct icm should likewise be unsigned int
per Linus' dictum:
https://lkml.org/lkml/2017/11/21/384


> --- a/drivers/thunderbolt/nhi.c
> +++ b/drivers/thunderbolt/nhi.c
> +/* Ice Lake specific NHI operations */
> +

Again, can't this be moved to a separate file for maintainability?

Thanks,

Lukas