From mboxrd@z Thu Jan 1 00:00:00 1970 From: Neil Horman Subject: Re: [PATCH 0/2] sctp: fix a problem with net_namespace Date: Mon, 10 Feb 2014 07:08:05 -0500 Message-ID: <20140210120805.GA32580@hmsreliant.think-freely.org> References: <1390794543-1008-1-git-send-email-wangweidong1@huawei.com> <20140127114904.GA17143@hmsreliant.think-freely.org> <52E766B8.3090406@huawei.com> <20140128115757.GA5002@hmsreliant.think-freely.org> <52F83FF3.6010307@huawei.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: davem@davemloft.net, vyasevich@gmail.com, dborkman@redhat.com, netdev@vger.kernel.org To: Wang Weidong Return-path: Received: from charlotte.tuxdriver.com ([70.61.120.58]:46822 "EHLO smtp.tuxdriver.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752276AbaBJMIs (ORCPT ); Mon, 10 Feb 2014 07:08:48 -0500 Content-Disposition: inline In-Reply-To: <52F83FF3.6010307@huawei.com> Sender: netdev-owner@vger.kernel.org List-ID: On Mon, Feb 10, 2014 at 10:56:51AM +0800, Wang Weidong wrote: > On 2014/1/28 19:57, Neil Horman wrote: > > On Tue, Jan 28, 2014 at 04:13:44PM +0800, Wang Weidong wrote: > >> On 2014/1/27 19:49, Neil Horman wrote: > >>> On Mon, Jan 27, 2014 at 11:49:01AM +0800, Wang Weidong wrote: > >>>> fix a problem with net_namespace, and optimize > >>>> the sctp_sysctl_net_register. > >>>> > >>>> Wang Weidong (2): > >>>> sctp: fix a missed .data initialization > >>>> sctp: optimize the sctp_sysctl_net_register > >>>> > >>>> net/sctp/sysctl.c | 17 ++++++++++------- > >>>> 1 file changed, 10 insertions(+), 7 deletions(-) > >>>> > >>>> -- > >>>> 1.7.12 > >>>> > >>>> > >>>> > >>> I don't see that either of these patches are needed. In sctp_init_net, the > >>> sctp_hmac_alg pointer gets initalized before calling sctp_sysctl_net_register, > >>> and sctp_proc_do_hmac_alg is written to specifically expect NULL values, so this > >>> code may change behavior regarding default cookie selection. > >>> > >> Hi Neil, > >> > >> Here, I think the sctp_proc_do_hmac_alg will be called only when we change the > >> /proc/sys/net/cookie_hmac_alg. So add the .data won't effect the default value. > >> and the data isn't equal to the "cookie_hmac_alg"? > >> > >>> This was coded so that poniters to entires in the string table could be used, > >>> rather than needing to allocate or maintain character buffers. That said, it > >>> does look like that for loop in sctp_sysctl_register_table might compute an odd > >>> offset when cloning the table. I think the right fix for that is likely to just > >>> move the sysctl value initalization in sctp_init_net to below the sysctl > >>> register function. > >>> > >>> Neil > >>> > >> > >> I found the problem is that: > >> I use "ip netns add netns1/netns2" > >> In any netns(netns1 or netns2 or init_net) when I change the value of the entry > >> such as "addip_enable" "max_autoclose" which after the cookie_hmac_alg (contain it), > >> and the other netns will be effected. > >> > >> In sctp_sysctl_net_register, kmemdup does cloning the table. The offset of netns1 and > >> init_net's clt_table.data is the same as two netns offset. So the for(){...} would do > >> add the offset for every clt_table.data. > >> > >> The code: > >> for (i = 0; table[i].data; i++) > >> table[i].data += (char *)(&net->sctp) - (char *)&init_net.sctp; > >> > >> And I add a pr_info into the for(){...} in sctp_sysctl_net_register and only print 7 times for each ns. > >> 7 is the index of "cookie_preserve_enable" which before the "cookie_hmac_alg". > >> > >> As the "cookie_hmac_alg" data is NULL, so we can't add offset to the rest, and all the netns use the same > >> address of clt_table entry after the "cookie_hmac_alg". > >> > >> So I think only "move the sysctl value initalization in sctp_init_net to below the sysctl > >> register function" won't solve the problem, because the problem is at the for() {...}. > >> > > I'm sorry, you're right, the kmemdup duplicates the table, not the structure in > > which the table points to with its .data pointers. I was looking at it > > backwards. > > > > Hi Neil, > > Should I resend "sctp: fix a problem with net_namespace" series again? > Not sure. I agree with your assesment on the table adjustments, but I think the discussion below is holding things up. You probably want to get to the root cause of whats causing the lockdep issue before that patch goes in for 1/2 though Acked-by: Neil Horman