netdev - Re: [PATCH net-next v2] net: core: decouple ifalias get/set from rtnl lock

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Message-ID: <1506957543.8061.14.camel@edumazet-glaptop3.roam.corp.google.com>
Date:   Mon, 02 Oct 2017 08:19:03 -0700
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     Florian Westphal <fw@...len.de>
Cc:     netdev@...r.kernel.org
Subject: Re: [PATCH net-next v2] net: core: decouple ifalias get/set from
 rtnl lock

On Mon, 2017-10-02 at 17:09 +0200, Florian Westphal wrote:
> Eric Dumazet <eric.dumazet@...il.com> wrote:
> > Just use RCU : A writer is supposed to work on a private copy, and
> > _then_ publish the new pointer, so that a reader can not see mangled
> > string.
> > 
> > We either copy the 'old' name or the 'new' one.
> > 
> > A seqcount is not needed, and wont prevent you from reading the value
> > right before a change anyway.
> 
> Would you rather use kfree_rcu or unconditional synchronize_net()
> before releasing old memory?

kfree_rcu() please ;)

Adding 16 bytes for the rcu_head is acceptable I think.