netdev - Re: [PATCH net-next v2 2/3] tipc: message reassembly using fragment chain

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Date:	Tue, 5 Nov 2013 09:15:26 +0100
From:	Erik Hugne <erik.hugne@...csson.com>
To:	David Miller <davem@...emloft.net>
CC:	<netdev@...r.kernel.org>, <jon.maloy@...csson.com>,
	<maloy@...jonn.com>, <paul.gortmaker@...driver.com>,
	<ying.xue@...driver.com>
Subject: Re: [PATCH net-next v2 2/3] tipc: message reassembly using fragment
 chain

On Mon, Nov 04, 2013 at 04:12:54PM -0500, David Miller wrote:
> From: <erik.hugne@...csson.com>
> Date: Thu, 31 Oct 2013 09:40:13 +0100
> 
> > +	skb_pull(frag, msg_hdr_sz(msg));
> > +	if (fragid == FIRST_FRAGMENT) {
> > +		if (*head)
> > +			goto out_free;
> > +		*head = frag;
> > +		skb_frag_list_init(*head);
> >  		return 0;
> > +	} else {
> > +		if (!*head)
> > +			goto out_free;
> > +		if (!skb_has_frag_list(*head))
> > +			skb_shinfo(*head)->frag_list = frag;
> > +		else
> > +			(*tail)->next = frag;
> > +		*tail = frag;
> > +		(*head)->truesize += frag->truesize;
> > +	}
> > +	if (fragid == LAST_FRAGMENT) {
> > +		*fbuf = *head;
> > +		*tail = *head = NULL;
> > +		return LINK_REASM_COMPLETE;
> >  	}
> 
> Please use skb_try_coalese(), and only use frag lists if that does not
> succeed.

Will fix.

> 
> Also you must be certain to unclone the SKB if you are going to modify
> it in this kind of way.

Is it enough to just unclone the list head skb?

> 
> For a good example of how to attend to all of these things, see
> ip_frag_reasm() in net/ipv4/ip_fragment.c

Thanks David.
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