From mboxrd@z Thu Jan  1 00:00:00 1970
From: Laurent Chavey <chavey@google.com>
Subject: Re: [PATCH] net: dev_getfirstbyhwtype() optimization
Date: Thu, 18 Mar 2010 14:54:44 -0700
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Cc: David Miller <davem@davemloft.net>, netdev <netdev@vger.kernel.org>
To: Eric Dumazet <eric.dumazet@gmail.com>
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reviewed_by: Laurent Chavey <chavey@google.com>


On Thu, Mar 18, 2010 at 2:27 PM, Eric Dumazet <eric.dumazet@gmail.com> =
wrote:
> Use RCU to avoid RTNL use in dev_getfirstbyhwtype()
>
> Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
> ---
> diff --git a/net/core/dev.c b/net/core/dev.c
> index 17b1686..0f2e9fc 100644
> --- a/net/core/dev.c
> +++ b/net/core/dev.c
> @@ -772,14 +772,17 @@ EXPORT_SYMBOL(__dev_getfirstbyhwtype);
>
> =A0struct net_device *dev_getfirstbyhwtype(struct net *net, unsigned =
short type)
> =A0{
> - =A0 =A0 =A0 struct net_device *dev;
> + =A0 =A0 =A0 struct net_device *dev, *ret =3D NULL;
>
> - =A0 =A0 =A0 rtnl_lock();
> - =A0 =A0 =A0 dev =3D __dev_getfirstbyhwtype(net, type);
> - =A0 =A0 =A0 if (dev)
> - =A0 =A0 =A0 =A0 =A0 =A0 =A0 dev_hold(dev);
> - =A0 =A0 =A0 rtnl_unlock();
> - =A0 =A0 =A0 return dev;
> + =A0 =A0 =A0 rcu_read_lock();
> + =A0 =A0 =A0 for_each_netdev_rcu(net, dev)
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 if (dev->type =3D=3D type) {
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 dev_hold(dev);
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 ret =3D dev;
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 break;
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 }
> + =A0 =A0 =A0 rcu_read_unlock();
> + =A0 =A0 =A0 return ret;
> =A0}
> =A0EXPORT_SYMBOL(dev_getfirstbyhwtype);
>
>
>
> --
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