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From: Florian Fainelli <f.fainelli@gmail.com>
To: Vladimir Oltean <vladimir.oltean@nxp.com>,
	netdev@vger.kernel.org, Jakub Kicinski <kuba@kernel.org>,
	"David S. Miller" <davem@davemloft.net>
Cc: Andrew Lunn <andrew@lunn.ch>,
	Vivien Didelot <vivien.didelot@gmail.com>,
	Jiri Pirko <jiri@resnulli.us>, Ido Schimmel <idosch@idosch.org>,
	Tobias Waldekranz <tobias@waldekranz.com>,
	Roopa Prabhu <roopa@nvidia.com>,
	Nikolay Aleksandrov <nikolay@nvidia.com>,
	Stephen Hemminger <stephen@networkplumber.org>,
	bridge@lists.linux-foundation.org,
	Grygorii Strashko <grygorii.strashko@ti.com>,
	Marek Behun <kabel@blackhole.sk>,
	DENG Qingfang <dqfext@gmail.com>
Subject: Re: [PATCH v4 net-next 07/15] net: bridge: disambiguate offload_fwd_mark
Date: Sun, 18 Jul 2021 19:26:45 -0700	[thread overview]
Message-ID: <4191ea0a-09ce-d52f-f40e-2d680ef4b9ca@gmail.com> (raw)
In-Reply-To: <20210718214434.3938850-8-vladimir.oltean@nxp.com>



On 7/18/2021 2:44 PM, Vladimir Oltean wrote:
> From: Tobias Waldekranz <tobias@waldekranz.com>
> 
> Before this change, four related - but distinct - concepts where named
> offload_fwd_mark:
> 
> - skb->offload_fwd_mark: Set by the switchdev driver if the underlying
>    hardware has already forwarded this frame to the other ports in the
>    same hardware domain.
> 
> - nbp->offload_fwd_mark: An idetifier used to group ports that share
>    the same hardware forwarding domain.
> 
> - br->offload_fwd_mark: Counter used to make sure that unique IDs are
>    used in cases where a bridge contains ports from multiple hardware
>    domains.
> 
> - skb->cb->offload_fwd_mark: The hardware domain on which the frame
>    ingressed and was forwarded.
> 
> Introduce the term "hardware forwarding domain" ("hwdom") in the
> bridge to denote a set of ports with the following property:
> 
>      If an skb with skb->offload_fwd_mark set, is received on a port
>      belonging to hwdom N, that frame has already been forwarded to all
>      other ports in hwdom N.
> 
> By decoupling the name from "offload_fwd_mark", we can extend the
> term's definition in the future - e.g. to add constraints that
> describe expected egress behavior - without overloading the meaning of
> "offload_fwd_mark".
> 
> - nbp->offload_fwd_mark thus becomes nbp->hwdom.
> 
> - br->offload_fwd_mark becomes br->last_hwdom.
> 
> - skb->cb->offload_fwd_mark becomes skb->cb->src_hwdom. The slight
>    change in naming here mandates a slight change in behavior of the
>    nbp_switchdev_frame_mark() function. Previously, it only set this
>    value in skb->cb for packets with skb->offload_fwd_mark true (ones
>    which were forwarded in hardware). Whereas now we always track the
>    incoming hwdom for all packets coming from a switchdev (even for the
>    packets which weren't forwarded in hardware, such as STP BPDUs, IGMP
>    reports etc). As all uses of skb->cb->offload_fwd_mark were already
>    gated behind checks of skb->offload_fwd_mark, this will not introduce
>    any functional change, but it paves the way for future changes where
>    the ingressing hwdom must be known for frames coming from a switchdev
>    regardless of whether they were forwarded in hardware or not
>    (basically, if the skb comes from a switchdev, skb->cb->src_hwdom now
>    always tracks which one).
> 
>    A typical example where this is relevant: the switchdev has a fixed
>    configuration to trap STP BPDUs, but STP is not running on the bridge
>    and the group_fwd_mask allows them to be forwarded. Say we have this
>    setup:
> 
>          br0
>         / | \
>        /  |  \
>    swp0 swp1 swp2
> 
>    A BPDU comes in on swp0 and is trapped to the CPU; the driver does not
>    set skb->offload_fwd_mark. The bridge determines that the frame should
>    be forwarded to swp{1,2}. It is imperative that forward offloading is
>    _not_ allowed in this case, as the source hwdom is already "poisoned".
> 
>    Recording the source hwdom allows this case to be handled properly.
> 
> v2->v3: added code comments
> v3->v4: none
> 
> Signed-off-by: Tobias Waldekranz <tobias@waldekranz.com>
> Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
> Reviewed-by: Grygorii Strashko <grygorii.strashko@ti.com>

Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
-- 
Florian

  reply	other threads:[~2021-07-19  2:26 UTC|newest]

Thread overview: 37+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-18 21:44 [PATCH v4 net-next 00/15] Allow forwarding for the software bridge data path to be offloaded to capable devices Vladimir Oltean
2021-07-18 21:44 ` [PATCH v4 net-next 01/15] net: dpaa2-switch: use extack in dpaa2_switch_port_bridge_join Vladimir Oltean
2021-07-19  9:17   ` Ioana Ciornei
2021-07-18 21:44 ` [PATCH v4 net-next 02/15] net: dpaa2-switch: refactor prechangeupper sanity checks Vladimir Oltean
2021-07-19  9:18   ` Ioana Ciornei
2021-07-18 21:44 ` [PATCH v4 net-next 03/15] mlxsw: spectrum: " Vladimir Oltean
2021-07-18 21:44 ` [PATCH v4 net-next 04/15] mlxsw: spectrum: refactor leaving an 8021q upper that is a bridge port Vladimir Oltean
2021-07-19  2:16   ` Florian Fainelli
2021-07-18 21:44 ` [PATCH v4 net-next 05/15] net: marvell: prestera: refactor prechangeupper sanity checks Vladimir Oltean
2021-07-19  2:20   ` Florian Fainelli
2021-07-18 21:44 ` [PATCH v4 net-next 06/15] net: switchdev: guard drivers against multiple obj replays on same bridge port Vladimir Oltean
2021-07-19  2:17   ` Florian Fainelli
2021-07-18 21:44 ` [PATCH v4 net-next 07/15] net: bridge: disambiguate offload_fwd_mark Vladimir Oltean
2021-07-19  2:26   ` Florian Fainelli [this message]
2021-07-18 21:44 ` [PATCH v4 net-next 08/15] net: bridge: switchdev: recycle unused hwdoms Vladimir Oltean
2021-07-18 21:44 ` [PATCH v4 net-next 09/15] net: bridge: switchdev: let drivers inform which bridge ports are offloaded Vladimir Oltean
2021-07-19  9:23   ` Ioana Ciornei
2021-07-20  7:53   ` Horatiu Vultur
2021-07-20  8:45     ` Vladimir Oltean
2021-07-18 21:44 ` [PATCH v4 net-next 10/15] net: bridge: switchdev object replay helpers for everybody Vladimir Oltean
2021-07-19  8:19   ` Vladimir Oltean
2021-07-19  9:26   ` Ioana Ciornei
2021-07-18 21:44 ` [PATCH v4 net-next 11/15] net: bridge: switchdev: allow the TX data plane forwarding to be offloaded Vladimir Oltean
2021-07-19  2:43   ` Florian Fainelli
2021-07-19  7:22   ` Vladimir Oltean
2021-07-18 21:44 ` [PATCH v4 net-next 12/15] net: dsa: track the number of switches in a tree Vladimir Oltean
2021-07-19  2:54   ` Florian Fainelli
2021-07-18 21:44 ` [PATCH v4 net-next 13/15] net: dsa: add support for bridge TX forwarding offload Vladimir Oltean
2021-07-19  2:51   ` Florian Fainelli
2021-07-18 21:44 ` [PATCH v4 net-next 14/15] net: dsa: mv88e6xxx: map virtual bridges with forwarding offload in the PVT Vladimir Oltean
2021-07-19  2:52   ` Florian Fainelli
2021-07-18 21:44 ` [PATCH v4 net-next 15/15] net: dsa: tag_dsa: offload the bridge forwarding process Vladimir Oltean
2021-07-19  2:47   ` Florian Fainelli
2021-07-19  7:41     ` Vladimir Oltean
2021-07-20 11:24 ` [PATCH v4 net-next 00/15] Allow forwarding for the software bridge data path to be offloaded to capable devices Ido Schimmel
2021-07-20 13:20   ` Vladimir Oltean
2021-07-20 13:51     ` Ido Schimmel

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