From: Florian Fainelli <f.fainelli@gmail.com>
To: Vladimir Oltean <olteanv@gmail.com>,
Jakub Kicinski <kuba@kernel.org>,
"David S. Miller" <davem@davemloft.net>,
netdev@vger.kernel.org
Cc: Andrew Lunn <andrew@lunn.ch>,
Vivien Didelot <vivien.didelot@gmail.com>,
Vladimir Oltean <vladimir.oltean@nxp.com>
Subject: Re: [PATCH net-next 4/6] net: dsa: calculate the largest_mtu across all ports in the tree
Date: Sun, 20 Jun 2021 07:23:37 -0700 [thread overview]
Message-ID: <c10dcd29-c601-93ed-e844-6c75ca3a74b4@gmail.com> (raw)
In-Reply-To: <20210618183017.3340769-5-olteanv@gmail.com>
On 6/18/2021 11:30 AM, Vladimir Oltean wrote:
> From: Vladimir Oltean <vladimir.oltean@nxp.com>
>
> If we have a cross-chip topology like this:
>
> sw0p0 sw0p1 sw0p2 sw0p3 sw0p4
> [ cpu ] [ user ] [ user ] [ dsa ] [ user ]
> |
> +---------+
> |
> sw1p0 sw1p1 sw1p2 sw1p3 sw1p4
> [ user ] [ user ] [ user ] [ dsa ] [ dsa ]
>
> and we issue the following commands:
>
> 1. ip link set sw0p1 mtu 1700
> 2. ip link set sw1p1 mtu 1600
>
> we notice the following happening:
>
> Command 1. emits a non-targeted MTU notifier for the CPU port (sw0p0)
> with the largest_mtu calculated across switch 0, of 1700. This matches
> sw0p0, sw0p3 and sw1p4 (all CPU ports and DSA links).
> Then, it emits a targeted MTU notifier for the user port (sw0p1), again
> with MTU 1700 (this doesn't matter).
>
> Command 2. emits a non-targeted MTU notifier for the CPU port (sw0p0)
> with the largest_mtu calculated across switch 1, of 1600. This matches
> the same group of ports as above, and decreases the MTU for the CPU port
> and the DSA links from 1700 to 1600.
>
> As a result, the sw0p1 user port can no longer communicate with its CPU
> port at MTU 1700.
>
> To address this, we should calculate the largest_mtu across all switches
> that may share a CPU port, and only emit MTU notifiers with that value.
>
> Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
--
Florian
next prev parent reply other threads:[~2021-06-20 14:24 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-18 18:30 [PATCH net-next 0/6] Improvement for DSA cross-chip setups Vladimir Oltean
2021-06-18 18:30 ` [PATCH net-next 1/6] net: dsa: assert uniqueness of dsa,member properties Vladimir Oltean
2021-06-19 1:59 ` Florian Fainelli
2021-06-21 13:53 ` Andrew Lunn
2021-06-18 18:30 ` [PATCH net-next 2/6] net: dsa: export the dsa_port_is_{user,cpu,dsa} helpers Vladimir Oltean
2021-06-19 2:00 ` Florian Fainelli
2021-06-21 13:55 ` Andrew Lunn
2021-06-18 18:30 ` [PATCH net-next 3/6] net: dsa: execute dsa_switch_mdb_add only for routing port in cross-chip topologies Vladimir Oltean
2021-06-20 14:24 ` Florian Fainelli
2021-06-18 18:30 ` [PATCH net-next 4/6] net: dsa: calculate the largest_mtu across all ports in the tree Vladimir Oltean
2021-06-20 14:23 ` Florian Fainelli [this message]
2021-06-18 18:30 ` [PATCH net-next 5/6] net: dsa: targeted MTU notifiers should only match on one port Vladimir Oltean
2021-06-20 14:25 ` Florian Fainelli
2021-06-18 18:30 ` [PATCH net-next 6/6] net: dsa: remove cross-chip support from the MRP notifiers Vladimir Oltean
2021-06-20 14:22 ` Florian Fainelli
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