From mboxrd@z Thu Jan 1 00:00:00 1970 From: Herbert Xu Subject: Re: [PATCH] netlink: enable skb header refcounting before sending first broadcast Date: Mon, 13 Jul 2015 16:10:40 +0800 Message-ID: <20150713081040.GB8971@gondor.apana.org.au> References: <20150710115141.12980.88829.stgit@buzz> <20150713072352.GA8485@gondor.apana.org.au> <1436774742.9402.3.camel@edumazet-glaptop2.roam.corp.google.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Konstantin Khlebnikov , netdev@vger.kernel.org, "David S. Miller" , Eric Dumazet To: Eric Dumazet Return-path: Received: from helcar.hengli.com.au ([209.40.204.226]:54651 "EHLO helcar.hengli.com.au" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751370AbbGMIKp (ORCPT ); Mon, 13 Jul 2015 04:10:45 -0400 Content-Disposition: inline In-Reply-To: <1436774742.9402.3.camel@edumazet-glaptop2.roam.corp.google.com> Sender: netdev-owner@vger.kernel.org List-ID: On Mon, Jul 13, 2015 at 10:05:42AM +0200, Eric Dumazet wrote: > > Herbert, UDP peek support is very buggy anyway, because of deferred > checksums > > __skb_checksum_complete() will happily manipulate csum, ip_summed, > csum_complete_sw & csum_valid > > Ideally, peek should never touch skb (but skb->users) I think UDP should be OK because the main creator of shared skbs is af_packet and in that cast the IP stack will clone the skb upon entry. AFAIK there aren't any entities doing the shared skb trick within the IP stack. IOW the UDP stack does not have to worry about share skbs, unlike netlink. Cheers, -- Email: Herbert Xu Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt