From: Ivan Vecera <ivecera@redhat.com>
To: Jiri Pirko <jiri@resnulli.us>
Cc: David Miller <davem@davemloft.net>,
idosch@idosch.org, andrew@lunn.ch, horatiu.vultur@microchip.com,
alexandre.belloni@bootlin.com, UNGLinuxDriver@microchip.com,
allan.nielsen@microchip.com, f.fainelli@gmail.com,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3 1/2] net: core: Notify on changes to dev->promiscuity.
Date: Fri, 30 Aug 2019 08:54:45 +0200 [thread overview]
Message-ID: <20190830085445.1c28dc02@ceranb> (raw)
In-Reply-To: <20190830063624.GN2312@nanopsycho>
On Fri, 30 Aug 2019 08:36:24 +0200
Jiri Pirko <jiri@resnulli.us> wrote:
> Fri, Aug 30, 2019 at 08:02:33AM CEST, davem@davemloft.net wrote:
> >From: Jiri Pirko <jiri@resnulli.us>
> >Date: Fri, 30 Aug 2019 07:39:40 +0200
> >
> >> Because the "promisc mode" would gain another meaning. Now how the
> >> driver should guess which meaning the user ment when he setted it?
> >> filter or trap?
> >>
> >> That is very confusing. If the flag is the way to do this, let's
> >> introduce another flag, like IFF_TRAPPING indicating that user
> >> wants exactly this.
> >
> >I don't understand how the meaning of promiscuous mode for a
> >networking device has suddenly become ambiguous, when did this start
> >happening?
>
> The promiscuity is a way to setup the rx filter. So promics == rx
> filter off. For normal nics, where there is no hw fwd datapath,
> this coincidentally means all received packets go to cpu.
> But if there is hw fwd datapath, rx filter is still off, all rxed
> packets are processed. But that does not mean they should be trapped
> to cpu.
+1
Promisc is Rx filtering option and should not imply that offloaded
traffic is trapped to CPU.
> Simple example:
> I need to see slowpath packets, for example arps/stp/bgp/... that
> are going to cpu, I do:
> tcpdump -i swp1
>
> I don't want to get all the traffic running over hw running this cmd.
> This is a valid usecase.
>
> To cope with hw fwd datapath devices, I believe that tcpdump has to
> have notion of that. Something like:
>
> tcpdump -i swp1 --hw-trapping-mode
>
> The logic can be inverse:
> tcpdump -i swp1
> tcpdump -i swp1 --no-hw-trapping-mode
>
> However, that would provide inconsistent behaviour between existing
> and patched tcpdump/kernel.
>
> All I'm trying to say, there are 2 flags
> needed (if we don't use tc trap).
next prev parent reply other threads:[~2019-08-30 6:54 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-29 9:22 [PATCH v3 0/2] net: core: Notify on changes to dev->promiscuity Horatiu Vultur
2019-08-29 9:22 ` [PATCH v3 1/2] " Horatiu Vultur
2019-08-29 9:51 ` Jiri Pirko
2019-08-29 10:56 ` Horatiu Vultur
2019-08-29 12:18 ` Jiri Pirko
2019-08-29 12:44 ` Horatiu Vultur
2019-08-29 12:55 ` Ivan Vecera
2019-08-29 13:15 ` Andrew Lunn
2019-08-29 13:39 ` Ivan Vecera
2019-08-29 13:15 ` Horatiu Vultur
2019-08-29 13:26 ` Andrew Lunn
2019-08-29 13:49 ` Jiri Pirko
2019-08-29 14:37 ` Andrew Lunn
2019-08-29 17:57 ` Ido Schimmel
2019-08-29 18:29 ` Andrew Lunn
2019-08-29 19:36 ` Ido Schimmel
2019-08-29 22:12 ` David Miller
2019-08-30 5:39 ` Jiri Pirko
2019-08-30 6:02 ` David Miller
2019-08-30 6:36 ` Jiri Pirko
2019-08-30 6:54 ` Ivan Vecera [this message]
2019-08-30 7:13 ` David Miller
2019-08-30 7:12 ` David Miller
2019-08-30 7:21 ` Jiri Pirko
2019-08-30 7:32 ` David Miller
2019-08-30 8:01 ` Jiri Pirko
2019-09-02 17:42 ` Allan W. Nielsen
2019-09-02 17:51 ` Jiri Pirko
2019-09-02 18:05 ` Allan W. Nielsen
2019-09-02 18:45 ` Jiri Pirko
2019-09-03 6:13 ` Ido Schimmel
2019-09-03 8:14 ` Allan W. Nielsen
2019-09-08 10:15 ` Ido Schimmel
2019-08-30 9:43 ` Ido Schimmel
2019-08-31 19:35 ` Andrew Lunn
2019-08-31 20:47 ` Ido Schimmel
2019-09-01 18:48 ` Andrew Lunn
2019-09-02 17:55 ` Allan W. Nielsen
2019-09-01 6:54 ` Jiri Pirko
2019-08-29 22:10 ` David Miller
2019-08-29 22:08 ` David Miller
2019-08-30 6:13 ` Jiri Pirko
2019-08-30 6:18 ` David Miller
2019-08-30 7:26 ` Ivan Vecera
2019-08-29 9:22 ` [PATCH v3 2/2] net: mscc: Implement promisc mode Horatiu Vultur
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