netdev - Re: [PATCH net v3] net: openvswitch: fix to make sure flow

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Date:   Sat, 17 Oct 2020 14:27:37 -0400 (EDT)
From:   Eelco Chaudron <echaudro@...hat.com>
To:     Jakub Kicinski <kuba@...nel.org>
Cc:     netdev@...r.kernel.org, davem@...emloft.net, dev@...nvswitch.org,
        pabeni@...hat.com, pshelar@....org, jlelli@...hat.com,
        bigeasy@...utronix.de, i maximets <i.maximets@....org>
Subject: Re: [PATCH net v3] net: openvswitch: fix to make sure flow_lookup()
 is not preempted



----- Original Message -----
> 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" <i.maximets@....org>
> Sent: Saturday, October 17, 2020 1:46:07 AM
> Subject: Re: [PATCH net v3] net: openvswitch: fix to make sure flow_lookup() is not preempted
> 
> On Thu, 15 Oct 2020 19:09:33 +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>
> 
> Hi Eelco, looks like this doesn't apply after the 5.10 merges.
> 
> Please respin on top of the current net.

Done, just sent out a v4.

//Eelco