From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754487AbaIXIPF (ORCPT ); Wed, 24 Sep 2014 04:15:05 -0400 Received: from ducie-dc1.codethink.co.uk ([185.25.241.215]:35220 "EHLO ducie-dc1.codethink.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753354AbaIXIPA (ORCPT ); Wed, 24 Sep 2014 04:15:00 -0400 Message-ID: <54227D7D.6020909@codethink.co.uk> Date: Wed, 24 Sep 2014 09:14:53 +0100 From: Rob Jones User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Icedove/24.7.0 MIME-Version: 1.0 To: Pablo Neira Ayuso , Ben Hutchings CC: davem@davemloft.net, coreteam@netfilter.org, netdev@vger.kernel.org, linux-kernel@codethink.co.uk, linux-kernel@vger.kernel.org, netfilter@vger.kernel.org, netfilter-devel@vger.kernel.org Subject: Re: [Linux-kernel] [PATCH v2] net/netfilter/x_tables.c: use __seq_open_private() References: <1411491955-9131-1-git-send-email-rob.jones@codethink.co.uk> <1411494387.32579.138.camel@xylophone> <20140923214021.GA4206@salvia> In-Reply-To: <20140923214021.GA4206@salvia> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 23/09/14 22:40, Pablo Neira Ayuso wrote: > On Tue, Sep 23, 2014 at 06:46:27PM +0100, Ben Hutchings wrote: >> On Tue, 2014-09-23 at 18:05 +0100, Rob Jones wrote: >>> Reduce boilerplate code by using __seq_open_private() instead of seq_open() >>> in xt_match_open() and xt_target_open(). >>> >>> Signed-off-by: Rob Jones >>> --- >>> >>> This patch uses an existing variant of seq_open() to reduce the kernel code >>> size. >>> >>> The only significant variation from the pre-existing code is the fact that >>> __seq_open_private() calls kzalloc() rather than kmalloc(), which could >>> conceivably have an impact on timing. >>> >>> This version 2 incorporates a minor initialisation simplification (resulting >>> from kzalloc() being used) requested by netfilter-devel@vger.kernel.org >> [...] >>> --- a/net/netfilter/x_tables.c >>> +++ b/net/netfilter/x_tables.c >>> @@ -1080,7 +1080,6 @@ static void *xt_mttg_seq_start(struct seq_file *seq, loff_t *pos, >>> struct nf_mttg_trav *trav = seq->private; >>> unsigned int j; >>> >>> - trav->class = MTTG_TRAV_INIT; >>> for (j = 0; j < *pos; ++j) >>> if (xt_mttg_seq_next(seq, NULL, NULL, is_target) == NULL) >>> return NULL; >> [...] >> >> I'm fairly sure this simplification is wrong, as xt_mttg_seq_start() is >> potentially called multiple times on the same file handle. Well spotted Ben. > > Right. I'm going to take v1 of this patch instead, sorry for the > inconvenience Rob. No problem at all. It gave me something to do on the train home last night :-) -- Rob Jones Codethink Ltd mailto:rob.jones@codethink.co.uk tel:+44 161 236 5575 From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rob Jones Subject: Re: [PATCH v2] net/netfilter/x_tables.c: use __seq_open_private() Date: Wed, 24 Sep 2014 09:14:53 +0100 Message-ID: <54227D7D.6020909@codethink.co.uk> References: <1411491955-9131-1-git-send-email-rob.jones@codethink.co.uk> <1411494387.32579.138.camel@xylophone> <20140923214021.GA4206@salvia> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: davem@davemloft.net, coreteam@netfilter.org, netdev@vger.kernel.org, linux-kernel@codethink.co.uk, linux-kernel@vger.kernel.org, netfilter@vger.kernel.org, netfilter-devel@vger.kernel.org To: Pablo Neira Ayuso , Ben Hutchings Return-path: In-Reply-To: <20140923214021.GA4206@salvia> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On 23/09/14 22:40, Pablo Neira Ayuso wrote: > On Tue, Sep 23, 2014 at 06:46:27PM +0100, Ben Hutchings wrote: >> On Tue, 2014-09-23 at 18:05 +0100, Rob Jones wrote: >>> Reduce boilerplate code by using __seq_open_private() instead of seq_open() >>> in xt_match_open() and xt_target_open(). >>> >>> Signed-off-by: Rob Jones >>> --- >>> >>> This patch uses an existing variant of seq_open() to reduce the kernel code >>> size. >>> >>> The only significant variation from the pre-existing code is the fact that >>> __seq_open_private() calls kzalloc() rather than kmalloc(), which could >>> conceivably have an impact on timing. >>> >>> This version 2 incorporates a minor initialisation simplification (resulting >>> from kzalloc() being used) requested by netfilter-devel@vger.kernel.org >> [...] >>> --- a/net/netfilter/x_tables.c >>> +++ b/net/netfilter/x_tables.c >>> @@ -1080,7 +1080,6 @@ static void *xt_mttg_seq_start(struct seq_file *seq, loff_t *pos, >>> struct nf_mttg_trav *trav = seq->private; >>> unsigned int j; >>> >>> - trav->class = MTTG_TRAV_INIT; >>> for (j = 0; j < *pos; ++j) >>> if (xt_mttg_seq_next(seq, NULL, NULL, is_target) == NULL) >>> return NULL; >> [...] >> >> I'm fairly sure this simplification is wrong, as xt_mttg_seq_start() is >> potentially called multiple times on the same file handle. Well spotted Ben. > > Right. I'm going to take v1 of this patch instead, sorry for the > inconvenience Rob. No problem at all. It gave me something to do on the train home last night :-) -- Rob Jones Codethink Ltd mailto:rob.jones@codethink.co.uk tel:+44 161 236 5575