netdev - Re: [PATCH RESEND net-next] net: Do synchronize_rcu() in ip6mr_sk

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Message-ID: <1520355533.109662.24.camel@gmail.com>
Date:   Tue, 06 Mar 2018 08:58:53 -0800
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     Kirill Tkhai <ktkhai@...tuozzo.com>, davem@...emloft.net,
        yoshfuji@...ux-ipv6.org, netdev@...r.kernel.org
Cc:     Yuval Mintz <yuvalm@...lanox.com>
Subject: Re: [PATCH RESEND net-next] net: Do synchronize_rcu() in
 ip6mr_sk_done() only if this is needed

On Tue, 2018-03-06 at 08:50 -0800, Eric Dumazet wrote:
> 
> But... what is this synchronize_rcu() doing exactly ?
> 
> This was added in 8571ab479a6e1ef46ead5ebee567e128a422767c
> 
> ("ip6mr: Make mroute_sk rcu-based")
> 
> Typically on a delete, the synchronize_rcu() would be needed before
> freeing the deleted object.
> 
> But nowadays we have better way : SOCK_RCU_FREE

To be clear, your patch is fine Kirill,

I am only sad seeing one can add a synchronize_rcu() in hot path
without anyone complaining during code review.

Reviewed-by: Eric Dumazet <edumazet@...gle.com>