netdev - Re: [PATCH net v4] net: openvswitch: fix to make sure flow

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Message-ID: <20201018124254.2ec023b0@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>
Date:   Sun, 18 Oct 2020 12:42:54 -0700
From:   Jakub Kicinski <kuba@...nel.org>
To:     Eelco Chaudron <echaudro@...hat.com>
Cc:     netdev@...r.kernel.org, davem@...emloft.net, dev@...nvswitch.org,
        pabeni@...hat.com, pshelar@....org, jlelli@...hat.com,
        bigeasy@...utronix.de, i.maximets@....org
Subject: Re: [PATCH net v4] net: openvswitch: fix to make sure flow_lookup()
 is not preempted

On Sat, 17 Oct 2020 20:24:51 +0200 Eelco Chaudron wrote:
> The flow_lookup() function uses per CPU variables, which must be called
> with BH disabled. However, this is fine in the general NAPI use case
> where the local BH is disabled. But, it's also called from the netlink
> context. The below patch makes sure that even in the netlink path, the
> BH is disabled.
> 
> In addition, u64_stats_update_begin() requires a lock to ensure one writer
> which is not ensured here. Making it per-CPU and disabling NAPI (softirq)
> ensures that there is always only one writer.
> 
> Fixes: eac87c413bf9 ("net: openvswitch: reorder masks array based on usage")
> Reported-by: Juri Lelli <jlelli@...hat.com>
> Signed-off-by: Eelco Chaudron <echaudro@...hat.com>

Applied and queued for 5.9.2. Thanks Eelco!