netdev - Re: [PATCH net-next v2] ipv4: fib: Replay events when registering FIB notifier

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20161102134845.GI1713@nanopsycho.orion>
Date:   Wed, 2 Nov 2016 14:48:45 +0100
From:   Jiri Pirko <jiri@...nulli.us>
To:     Roopa Prabhu <roopa@...ulusnetworks.com>
Cc:     Ido Schimmel <idosch@...sch.org>,
        Eric Dumazet <eric.dumazet@...il.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "davem@...emloft.net" <davem@...emloft.net>,
        Jiri Pirko <jiri@...lanox.com>, mlxsw <mlxsw@...lanox.com>,
        David Ahern <dsa@...ulusnetworks.com>,
        Nikolay Aleksandrov <nikolay@...ulusnetworks.com>,
        Andy Gospodarek <andy@...yhouse.net>,
        Vivien Didelot <vivien.didelot@...oirfairelinux.com>,
        Andrew Lunn <andrew@...n.ch>,
        Florian Fainelli <f.fainelli@...il.com>,
        alexander.h.duyck@...el.com,
        Alexey Kuznetsov <kuznet@....inr.ac.ru>,
        James Morris <jmorris@...ei.org>,
        Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
        Patrick McHardy <kaber@...sh.net>,
        Ido Schimmel <idosch@...lanox.com>
Subject: Re: [PATCH net-next v2] ipv4: fib: Replay events when registering
 FIB notifier

Wed, Nov 02, 2016 at 02:29:40PM CET, roopa@...ulusnetworks.com wrote:
>On Wed, Nov 2, 2016 at 12:20 AM, Jiri Pirko <jiri@...nulli.us> wrote:
>> Wed, Nov 02, 2016 at 03:13:42AM CET, roopa@...ulusnetworks.com wrote:
>>>
>[snip]
>
>>>I understand..but, if you are adding some core infrastructure for switchdev ..it cannot be
>>>based on the number of simple use-cases or data you have today.
>>>
>>>I won't be surprised if tomorrow other switch drivers have a case where they need to
>>>reset the hw routing table state and reprogram all routes again. Re-registering the notifier to just
>>>get the routing state of the kernel will not scale. For the long term, since the driver does not maintain a cache,
>>
>> Driver (mlxsw, rocker) maintain a cache. So I'm not sure why you say
>> otherwise.
>>
>>
>>>a pull api with efficient use of rtnl will be useful for other such cases as well.
>>
>> How do you imagine this "pull API" should look like?
>
>
>Just like you already have added fib notifiers to parallel fib netlink
>notifications, the pull API is  a parallel to 'netlink dump'.
>Is my imagination too wild  ? :)

Perhaps I'm slow, but I don't understand what you mean.


>
>
>>
>>
>>>
>>>
>>>If you don't want to get to the complexity of a new api right away because of the
>>>simple case of management interface routes you have, Can your driver register the notifier early  ?
>>>(I am sure you have probably already thought about this)
>>
>> Register early? What it would resolve? I must be missing something. We
>> register as early as possible. But the thing is, we cannot register
>> in a past. And that is what this patch resolves.
>
>sure, you must be having a valid problem then. I was just curious why
>your driver is not up and initialized before any of the addresses or
>routes get configured in the system (even on a management port). Ours

If you unload the module and load it again for example. This is a valid
usecase.


>does. But i agree there can be races and you cannot always guarantee
>(I was just responding to ido's comment about adding complexity for a
>small problem he has to solve for management routes). Our driver does
>a pull before it starts. This helps when we want to reset the hardware
>routing table state too.

Can you point me to you driver in the tree? I would like to see how you
do "the pull".


>
>
>But, my point was, when you are defining an API, you cannot quantify
>the 'past' to be just the very 'close past' or 'the past is just the
>management routes that were added' . Tomorrow the 'past' can be the
>full routing table if you need to reset the hardware state.

Sure.