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- From 9d5ef190e5615a7b63af89f88c4106a5bc127974 Mon Sep 17 00:00:00 2001
- From: Vladimir Oltean <[email protected]>
- Date: Fri, 5 Feb 2021 15:37:10 +0200
- Subject: [PATCH] net: dsa: automatically bring up DSA master when opening user
- port
- DSA wants the master interface to be open before the user port is due to
- historical reasons. The promiscuity of interfaces that are down used to
- have issues, as referenced Lennert Buytenhek in commit df02c6ff2e39
- ("dsa: fix master interface allmulti/promisc handling").
- The bugfix mentioned there, commit b6c40d68ff64 ("net: only invoke
- dev->change_rx_flags when device is UP"), was basically a "don't do
- that" approach to working around the promiscuity while down issue.
- Further work done by Vlad Yasevich in commit d2615bf45069 ("net: core:
- Always propagate flag changes to interfaces") has resolved the
- underlying issue, and it is strictly up to the DSA and 8021q drivers
- now, it is no longer mandated by the networking core that the master
- interface must be up when changing its promiscuity.
- From DSA's point of view, deciding to error out in dsa_slave_open
- because the master isn't up is
- (a) a bad user experience and
- (b) knocking at an open door.
- Even if there still was an issue with promiscuity while down, DSA could
- still just open the master and avoid it.
- Doing it this way has the additional benefit that user space can now
- remove DSA-specific workarounds, like systemd-networkd with BindCarrier:
- https://github.com/systemd/systemd/issues/7478
- And we can finally remove one of the 2 bullets in the "Common pitfalls
- using DSA setups" chapter.
- Tested with two cascaded DSA switches:
- $ ip link set sw0p2 up
- fsl_enetc 0000:00:00.2 eno2: configuring for fixed/internal link mode
- fsl_enetc 0000:00:00.2 eno2: Link is Up - 1Gbps/Full - flow control rx/tx
- mscc_felix 0000:00:00.5 swp0: configuring for fixed/sgmii link mode
- mscc_felix 0000:00:00.5 swp0: Link is Up - 1Gbps/Full - flow control off
- 8021q: adding VLAN 0 to HW filter on device swp0
- sja1105 spi2.0 sw0p2: configuring for phy/rgmii-id link mode
- IPv6: ADDRCONF(NETDEV_CHANGE): eno2: link becomes ready
- IPv6: ADDRCONF(NETDEV_CHANGE): swp0: link becomes ready
- Signed-off-by: Vladimir Oltean <[email protected]>
- Reviewed-by: Andrew Lunn <[email protected]>
- Reviewed-by: Florian Fainelli <[email protected]>
- Signed-off-by: Jakub Kicinski <[email protected]>
- ---
- Documentation/networking/dsa/dsa.rst | 4 ----
- net/dsa/slave.c | 7 +++++--
- 2 files changed, 5 insertions(+), 6 deletions(-)
- --- a/Documentation/networking/dsa/dsa.rst
- +++ b/Documentation/networking/dsa/dsa.rst
- @@ -273,10 +273,6 @@ will not make us go through the switch t
- the Ethernet switch on the other end, expecting a tag will typically drop this
- frame.
-
- -Slave network devices check that the master network device is UP before allowing
- -you to administratively bring UP these slave network devices. A common
- -configuration mistake is forgetting to bring UP the master network device first.
- -
- Interactions with other subsystems
- ==================================
-
- --- a/net/dsa/slave.c
- +++ b/net/dsa/slave.c
- @@ -68,8 +68,11 @@ static int dsa_slave_open(struct net_dev
- struct dsa_port *dp = dsa_slave_to_port(dev);
- int err;
-
- - if (!(master->flags & IFF_UP))
- - return -ENETDOWN;
- + err = dev_open(master, NULL);
- + if (err < 0) {
- + netdev_err(dev, "failed to open master %s\n", master->name);
- + goto out;
- + }
-
- if (!ether_addr_equal(dev->dev_addr, master->dev_addr)) {
- err = dev_uc_add(master, dev->dev_addr);
|
