netdev - Re: [PATCH net-next] net: nexthop: reduce rcu synchronizations when replacing resilient groups

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Message-ID: <YaTjsHnf3kpH3SqW@shredder>
Date:   Mon, 29 Nov 2021 16:29:04 +0200
From:   Ido Schimmel <idosch@...sch.org>
To:     Nikolay Aleksandrov <razor@...ckwall.org>
Cc:     netdev@...r.kernel.org, davem@...emloft.net, kuba@...nel.org,
        dsahern@...il.com, Nikolay Aleksandrov <nikolay@...dia.com>
Subject: Re: [PATCH net-next] net: nexthop: reduce rcu synchronizations when
 replacing resilient groups

On Mon, Nov 29, 2021 at 02:09:24PM +0200, Nikolay Aleksandrov wrote:
> From: Nikolay Aleksandrov <nikolay@...dia.com>
> 
> We can optimize resilient nexthop group replaces by reducing the number of
> synchronize_net calls. After commit 1005f19b9357 ("net: nexthop: release
> IPv6 per-cpu dsts when replacing a nexthop group") we always do a
> synchronize_net because we must ensure no new dsts can be created for the
> replaced group's removed nexthops, but we already did that when replacing
> resilient groups, so if we always call synchronize_net after any group
> type replacement we'll take care of both cases and reduce synchronize_net
> calls for resilient groups.
> 
> Suggested-by: Ido Schimmel <idosch@...sch.org>
> Signed-off-by: Nikolay Aleksandrov <nikolay@...dia.com>

I ran fib_nexthops.sh that used to trigger the bug fixed by commit
563f23b00253 ("nexthop: Fix division by zero while replacing a resilient
group") and it looks good.

Reviewed-by: Ido Schimmel <idosch@...dia.com>
Tested-by: Ido Schimmel <idosch@...dia.com>

Thanks!