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Date: Tue, 28 Jan 2014 16:13:44 +0800 From: Wang Weidong <wangweidong1@...wei.com> To: Neil Horman <nhorman@...driver.com> CC: <davem@...emloft.net>, <vyasevich@...il.com>, <dborkman@...hat.com>, <netdev@...r.kernel.org> Subject: Re: [PATCH 0/2] sctp: fix a problem with net_namespace 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() {...}. Is there something wrong? The next patch is that, the sctp_net_table is for init_net, So when load the sctp module, we needn't to do the cloning tables for init_net again. And I found the ipv4 do it in the same way. I have a doubt : how can I rmmod the sctp? only add '-f' ? If I do "rmmod -f sctp", I will get the log by dmesg: "Disabling lock debugging due to kernel taint" Regards, Wang > > -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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