Messages in this thread | | | From | Rocco Yue <> | Subject | Re: [PATCH net-next v3] ipv6: add IFLA_INET6_RA_MTU to expose mtu value in the RA message | Date | Fri, 13 Aug 2021 16:07:40 +0800 |
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On Wed, 2021-08-11 at 12:05 -0600, David Ahern wrote: > On 8/11/21 7:56 AM, David Ahern wrote: >> On 8/10/21 6:33 AM, Rocco Yue wrote: >>> On Mon, 2021-08-09 at 16:43 -0600, David Ahern wrote: >>>> >>>> Since this MTU is getting reported via af_info infrastructure, >>>> rtmsg_ifinfo should be sufficient. >>>> >>>> From there use 'ip monitor' to make sure you are not generating multiple >>>> notifications; you may only need this on the error path. >>> >>> Hi David, >>> >>> To avoid generating multiple notifications, I added a separate ramtu notify >>> function in this patch, and I added RTNLGRP_IPV6_IFINFO nl_mgrp to the ipmonitor.c >>> to verify this patch was as expected. >>> >>> I look at the rtmsg_ifinfo code, it should be appropriate and I will use it and >>> verify it. >>> >>> But there's one thing, I'm sorry I didn't fully understand the meaning of this >>> sentence "you may only need this on the error path". Honestly, I'm not sure what >>> the error patch refers to, do you mean "if (mtu < IPV6_MIN_MTU || mtu > skb->dev->mtu)" ? >>> >> >> looks like nothing under: >> if (ndopts.nd_opts_mtu && in6_dev->cnf.accept_ra_mtu) { >> >> } >> >> is going to send a link notification so you can just replace >> inet6_iframtu_notify with rtmsg_ifinfo in your proposed change. >> > > Taking a deeper dive on the code, you do not need to call rtmsg_ifinfo. > Instead, the existing: > > /* > * Send a notify if RA changed managed/otherconf flags or > timer settings > */ > if (send_ifinfo_notify) > inet6_ifinfo_notify(RTM_NEWLINK, in6_dev); > > is called too early. For one the RA can change the MTU and that is done > after this notify. > > I think if you moved this down to the out: > > out: > /* > * Send a notify if RA changed managed/otherconf flags or > timer settings > */ > if (send_ifinfo_notify) > inet6_ifinfo_notify(RTM_NEWLINK, in6_dev); > > and then set send_ifinfo_notify when the mtu is *changed* by the RA you > should be good.
Hi David,
Thanks for your suggestion, this looks like a better choice without adding a separate notification function, I will modify it and push the next iteration .
Best Regards, Rocco
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