netdev - RE: [RFC PATCH] netlink: Increase netlink dump skb message size

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Date:	Tue, 26 Apr 2011 09:02:21 -0700
From:	"Rose, Gregory V" <gregory.v.rose@...el.com>
To:	Eric Dumazet <eric.dumazet@...il.com>
CC:	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"bhutchings@...arflare.com" <bhutchings@...arflare.com>,
	"davem@...emloft.net" <davem@...emloft.net>
Subject: RE: [RFC PATCH] netlink: Increase netlink dump skb message size

> -----Original Message-----
> From: Eric Dumazet [mailto:eric.dumazet@...il.com]
> Sent: Monday, April 25, 2011 11:33 PM
> To: Rose, Gregory V
> Cc: netdev@...r.kernel.org; bhutchings@...arflare.com; davem@...emloft.net
> Subject: Re: [RFC PATCH] netlink: Increase netlink dump skb message size
> 
> Le lundi 25 avril 2011 à 15:01 -0700, Greg Rose a écrit :
> > The message size allocated for rtnl info dumps was limited to a single
> page.
> > This is not enough for additional interface info available with devices
> > that support SR-IOV.  Check that the amount of data allocated is
> sufficient
> > for the amount of data requested.
> >
> > Signed-off-by: Greg Rose <gregory.v.rose@...el.com>
> > ---
> >
> >  include/linux/rtnetlink.h |    1 +
> >  net/core/rtnetlink.c      |    6 ++++++
> >  net/netlink/af_netlink.c  |   37 +++++++++++++++++++++++++++++++------
> >  3 files changed, 38 insertions(+), 6 deletions(-)
> >
> 
> Hmm, thats a hack, because netlink_dump() is generic and you add
> something very specific.
> 
> I prefer something that allows one dump() to reallocate a bigger skb
> 
> Maybe changing->dump() prototype to struct sk_buff **pskb instead of
> struct sk_buff *skb.

I'll have a look at that, although Dave's not too happy with the whole lot of this mess and I very much agree with him.

- Greg
> 
> diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
> index c8f35b5..7fa6735 100644
> --- a/net/netlink/af_netlink.c
> +++ b/net/netlink/af_netlink.c
> @@ -1681,7 +1681,7 @@ static int netlink_dump(struct sock *sk)
>  		goto errout_skb;
>  	}
> 
> -	len = cb->dump(skb, cb);
> +	len = cb->dump(&skb, cb);
> 
>  	if (len > 0) {
>  		mutex_unlock(nlk->cb_mutex);
>