netdev - Re: [PATCH v2 net-next 2/7] net: dsa: merge all bools of struct dsa

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Date:   Wed, 5 Jan 2022 18:39:34 +0000
From:   Vladimir Oltean <vladimir.oltean@....com>
To:     Florian Fainelli <f.fainelli@...il.com>
CC:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>, Andrew Lunn <andrew@...n.ch>,
        Vivien Didelot <vivien.didelot@...il.com>
Subject: Re: [PATCH v2 net-next 2/7] net: dsa: merge all bools of struct
 dsa_port into a single u8

Hi Florian,

On Wed, Jan 05, 2022 at 10:30:54AM -0800, Florian Fainelli wrote:
> Reviewed-by: Florian Fainelli <f.fainelli@...il.com>

Thanks a lot for the review.

I'm a bit on the fence on this patch and the other one for dsa_switch.
The thing is that bit fields are not atomic in C89, so if we update any
of the flags inside dp or ds concurrently (like dp->vlan_filtering),
we're in trouble. Right now this isn't a problem, because most of the
flags are set either during probe, or during ds->ops->setup, or are
serialized by the rtnl_mutex in ways that are there to stay (switchdev
notifiers). That's why I didn't say anything about it. But it may be a
caveat to watch out for in the future. Do you think we need to do
something about it? A lock would not be necessary, strictly speaking.