kernel/linux.git/drivers/net/dsa/dsa_loop.c, branch v5.19

net: dsa: pass extack to .port_bridge_join driver methods

2022-02-27T11:06:14+00:00

As FDB isolation cannot be enforced between VLAN-aware bridges in lack of hardware assistance like extra FID bits, it seems plausible that many DSA switches cannot do it. Therefore, they need to reject configurations with multiple VLAN-aware bridges from the two code paths that can transition towards that state: - joining a VLAN-aware bridge - toggling VLAN awareness on an existing bridge The .port_vlan_filtering method already propagates the netlink extack to the driver, let's propagate it from .port_bridge_join too, to make sure that the driver can use the same function for both. Signed-off-by: Vladimir Oltean Signed-off-by: David S. Miller

net: dsa: add a "tx_fwd_offload" argument to ->port_bridge_join

2021-12-08T22:31:16+00:00

This is a preparation patch for the removal of the DSA switch methods ->port_bridge_tx_fwd_offload() and ->port_bridge_tx_fwd_unoffload(). The plan is for the switch to report whether it offloads TX forwarding directly as a response to the ->port_bridge_join() method. This change deals with the noisy portion of converting all existing function prototypes to take this new boolean pointer argument. The bool is placed in the cross-chip notifier structure for bridge join, and a reference to it is provided to drivers. In the next change, DSA will then actually look at this value instead of calling ->port_bridge_tx_fwd_offload(). Signed-off-by: Vladimir Oltean Reviewed-by: Alvin Šipraga Signed-off-by: Jakub Kicinski

net: dsa: keep the bridge_dev and bridge_num as part of the same structure

2021-12-08T22:31:16+00:00

The main desire behind this is to provide coherent bridge information to the fast path without locking. For example, right now we set dp->bridge_dev and dp->bridge_num from separate code paths, it is theoretically possible for a packet transmission to read these two port properties consecutively and find a bridge number which does not correspond with the bridge device. Another desire is to start passing more complex bridge information to dsa_switch_ops functions. For example, with FDB isolation, it is expected that drivers will need to be passed the bridge which requested an FDB/MDB entry to be offloaded, and along with that bridge_dev, the associated bridge_num should be passed too, in case the driver might want to implement an isolation scheme based on that number. We already pass the {bridge_dev, bridge_num} pair to the TX forwarding offload switch API, however we'd like to remove that and squash it into the basic bridge join/leave API. So that means we need to pass this pair to the bridge join/leave API. During dsa_port_bridge_leave, first we unset dp->bridge_dev, then we call the driver's .port_bridge_leave with what used to be our dp->bridge_dev, but provided as an argument. When bridge_dev and bridge_num get folded into a single structure, we need to preserve this behavior in dsa_port_bridge_leave: we need a copy of what used to be in dp->bridge. Switch drivers check bridge membership by comparing dp->bridge_dev with the provided bridge_dev, but now, if we provide the struct dsa_bridge as a pointer, they cannot keep comparing dp->bridge to the provided pointer, since this only points to an on-stack copy. To make this obvious and prevent driver writers from forgetting and doing stupid things, in this new API, the struct dsa_bridge is provided as a full structure (not very large, contains an int and a pointer) instead of a pointer. An explicit comparison function needs to be used to determine bridge membership: dsa_port_offloads_bridge(). Signed-off-by: Vladimir Oltean Reviewed-by: Alvin Šipraga Signed-off-by: Jakub Kicinski

net: dsa: be compatible with masters which unregister on shutdown

2021-09-19T11:08:37+00:00

Lino reports that on his system with bcmgenet as DSA master and KSZ9897 as a switch, rebooting or shutting down never works properly. What does the bcmgenet driver have special to trigger this, that other DSA masters do not? It has an implementation of ->shutdown which simply calls its ->remove implementation. Otherwise said, it unregisters its network interface on shutdown. This message can be seen in a loop, and it hangs the reboot process there: unregister_netdevice: waiting for eth0 to become free. Usage count = 3 So why 3? A usage count of 1 is normal for a registered network interface, and any virtual interface which links itself as an upper of that will increment it via dev_hold. In the case of DSA, this is the call path: dsa_slave_create -> netdev_upper_dev_link -> __netdev_upper_dev_link -> __netdev_adjacent_dev_insert -> dev_hold So a DSA switch with 3 interfaces will result in a usage count elevated by two, and netdev_wait_allrefs will wait until they have gone away. Other stacked interfaces, like VLAN, watch NETDEV_UNREGISTER events and delete themselves, but DSA cannot just vanish and go poof, at most it can unbind itself from the switch devices, but that must happen strictly earlier compared to when the DSA master unregisters its net_device, so reacting on the NETDEV_UNREGISTER event is way too late. It seems that it is a pretty established pattern to have a driver's ->shutdown hook redirect to its ->remove hook, so the same code is executed regardless of whether the driver is unbound from the device, or the system is just shutting down. As Florian puts it, it is quite a big hammer for bcmgenet to unregister its net_device during shutdown, but having a common code path with the driver unbind helps ensure it is well tested. So DSA, for better or for worse, has to live with that and engage in an arms race of implementing the ->shutdown hook too, from all individual drivers, and do something sane when paired with masters that unregister their net_device there. The only sane thing to do, of course, is to unlink from the master. However, complications arise really quickly. The pattern of redirecting ->shutdown to ->remove is not unique to bcmgenet or even to net_device drivers. In fact, SPI controllers do it too (see dspi_shutdown -> dspi_remove), and presumably, I2C controllers and MDIO controllers do it too (this is something I have not researched too deeply, but even if this is not the case today, it is certainly plausible to happen in the future, and must be taken into consideration). Since DSA switches might be SPI devices, I2C devices, MDIO devices, the insane implication is that for the exact same DSA switch device, we might have both ->shutdown and ->remove getting called. So we need to do something with that insane environment. The pattern I've come up with is "if this, then not that", so if either ->shutdown or ->remove gets called, we set the device's drvdata to NULL, and in the other hook, we check whether the drvdata is NULL and just do nothing. This is probably not necessary for platform devices, just for devices on buses, but I would really insist for consistency among drivers, because when code is copy-pasted, it is not always copy-pasted from the best sources. So depending on whether the DSA switch's ->remove or ->shutdown will get called first, we cannot really guarantee even for the same driver if rebooting will result in the same code path on all platforms. But nonetheless, we need to do something minimally reasonable on ->shutdown too to fix the bug. Of course, the ->remove will do more (a full teardown of the tree, with all data structures freed, and this is why the bug was not caught for so long). The new ->shutdown method is kept separate from dsa_unregister_switch not because we couldn't have unregistered the switch, but simply in the interest of doing something quick and to the point. The big question is: does the DSA switch's ->shutdown get called earlier than the DSA master's ->shutdown? If not, there is still a risk that we might still trigger the WARN_ON in unregister_netdevice that says we are attempting to unregister a net_device which has uppers. That's no good. Although the reference to the master net_device won't physically go away even if DSA's ->shutdown comes afterwards, remember we have a dev_hold on it. The answer to that question lies in this comment above device_link_add: * A side effect of the link creation is re-ordering of dpm_list and the * devices_kset list by moving the consumer device and all devices depending * on it to the ends of these lists (that does not happen to devices that have * not been registered when this function is called). so the fact that DSA uses device_link_add towards its master is not exactly for nothing. device_shutdown() walks devices_kset from the back, so this is our guarantee that DSA's shutdown happens before the master's shutdown. Fixes: 2f1e8ea726e9 ("net: dsa: link interfaces with the DSA master to get rid of lockdep warnings") Link: https://lore.kernel.org/netdev/20210909095324.12978-1-LinoSanfilippo@gmx.de/ Reported-by: Lino Sanfilippo Signed-off-by: Vladimir Oltean Tested-by: Andrew Lunn Signed-off-by: David S. Miller

net: dsa: propagate extack to .port_vlan_filtering

2021-02-15T01:38:12+00:00

Some drivers can't dynamically change the VLAN filtering option, or impose some restrictions, it would be nice to propagate this info through netlink instead of printing it to a kernel log that might never be read. Also netlink extack includes the module that emitted the message, which means that it's easier to figure out which ones are driver-generated errors as opposed to command misuse. Signed-off-by: Vladimir Oltean Reviewed-by: Florian Fainelli Signed-off-by: David S. Miller

net: dsa: propagate extack to .port_vlan_add

2021-02-15T01:38:11+00:00

Allow drivers to communicate their restrictions to user space directly, instead of printing to the kernel log. Where the conversion would have been lossy and things like VLAN ID could no longer be conveyed (due to the lack of support for printf format specifier in netlink extack), I chose to keep the messages in full form to the kernel log only, and leave it up to individual driver maintainers to move more messages to extack. Signed-off-by: Vladimir Oltean Reviewed-by: Florian Fainelli Signed-off-by: David S. Miller

net: dsa: Fix off by one in dsa_loop_port_vlan_add()

2021-01-21T01:10:04+00:00

The > comparison is intended to be >= to prevent reading beyond the end of the ps->vlans[] array. It doesn't affect run time though because the ps->vlans[] array has VLAN_N_VID (4096) elements and the vlan->vid cannot be > 4094 because it is checked earlier. Signed-off-by: Dan Carpenter Acked-by: Florian Fainelli Link: https://lore.kernel.org/r/YAbyb5kBJQlpYCs2@mwanda Signed-off-by: Jakub Kicinski

net: dsa: set configure_vlan_while_not_filtering to true by default

2021-01-16T01:29:40+00:00

As explained in commit 54a0ed0df496 ("net: dsa: provide an option for drivers to always receive bridge VLANs"), DSA has historically been skipping VLAN switchdev operations when the bridge wasn't in vlan_filtering mode, but the reason why it was doing that has never been clear. So the configure_vlan_while_not_filtering option is there merely to preserve functionality for existing drivers. It isn't some behavior that drivers should opt into. Ideally, when all drivers leave this flag set, we can delete the dsa_port_skip_vlan_configuration() function. New drivers always seem to omit setting this flag, for some reason. So let's reverse the logic: the DSA core sets it by default to true before the .setup() callback, and legacy drivers can turn it off. This way, new drivers get the new behavior by default, unless they explicitly set the flag to false, which is more obvious during review. Remove the assignment from drivers which were setting it to true, and add the assignment to false for the drivers that didn't previously have it. This way, it should be easier to see how many we have left. The following drivers: lan9303, mv88e6060 were skipped from setting this flag to false, because they didn't have any VLAN offload ops in the first place. The Broadcom Starfighter 2 driver calls the common b53_switch_alloc and therefore also inherits the configure_vlan_while_not_filtering=true behavior. Also, print a message through netlink extack every time a VLAN has been skipped. This is mildly annoying on purpose, so that (a) it is at least clear that VLANs are being skipped - the legacy behavior in itself is confusing, and the extack should be much more difficult to miss, unlike kernel logs - and (b) people have one more incentive to convert to the new behavior. No behavior change except for the added prints is intended at this time. $ ip link add br0 type bridge vlan_filtering 0 $ ip link set sw0p2 master br0 [ 60.315148] br0: port 1(sw0p2) entered blocking state [ 60.320350] br0: port 1(sw0p2) entered disabled state [ 60.327839] device sw0p2 entered promiscuous mode [ 60.334905] br0: port 1(sw0p2) entered blocking state [ 60.340142] br0: port 1(sw0p2) entered forwarding state Warning: dsa_core: skipping configuration of VLAN. # This was the pvid $ bridge vlan add dev sw0p2 vid 100 Warning: dsa_core: skipping configuration of VLAN. Signed-off-by: Vladimir Oltean Reviewed-by: Kurt Kanzenbach Reviewed-by: Florian Fainelli Link: https://lore.kernel.org/r/20210115231919.43834-1-vladimir.oltean@nxp.com Signed-off-by: Jakub Kicinski

net: dsa: remove the transactional logic from VLAN objects

2021-01-12T00:00:57+00:00

It should be the driver's business to logically separate its VLAN offloading into a preparation and a commit phase, and some drivers don't need / can't do this. So remove the transactional shim from DSA and let drivers propagate errors directly from the .port_vlan_add callback. It would appear that the code has worse error handling now than it had before. DSA is the only in-kernel user of switchdev that offloads one switchdev object to more than one port: for every VLAN object offloaded to a user port, that VLAN is also offloaded to the CPU port. So the "prepare for user port -> check for errors -> prepare for CPU port -> check for errors -> commit for user port -> commit for CPU port" sequence appears to make more sense than the one we are using now: "offload to user port -> check for errors -> offload to CPU port -> check for errors", but it is really a compromise. In the new way, we can catch errors from the commit phase that we previously had to ignore. But we have our hands tied and cannot do any rollback now: if we add a VLAN on the CPU port and it fails, we can't do the rollback by simply deleting it from the user port, because the switchdev API is not so nice with us: it could have simply been there already, even with the same flags. So we don't even attempt to rollback anything on addition error, just leave whatever VLANs managed to get offloaded right where they are. This should not be a problem at all in practice. Signed-off-by: Vladimir Oltean Reviewed-by: Florian Fainelli Acked-by: Linus Walleij Acked-by: Jiri Pirko Signed-off-by: Jakub Kicinski

net: switchdev: remove the transaction structure from port attributes

2021-01-12T00:00:57+00:00

Since the introduction of the switchdev API, port attributes were transmitted to drivers for offloading using a two-step transactional model, with a prepare phase that was supposed to catch all errors, and a commit phase that was supposed to never fail. Some classes of failures can never be avoided, like hardware access, or memory allocation. In the latter case, merely attempting to move the memory allocation to the preparation phase makes it impossible to avoid memory leaks, since commit 91cf8eceffc1 ("switchdev: Remove unused transaction item queue") which has removed the unused mechanism of passing on the allocated memory between one phase and another. It is time we admit that separating the preparation from the commit phase is something that is best left for the driver to decide, and not something that should be baked into the API, especially since there are no switchdev callers that depend on this. This patch removes the struct switchdev_trans member from switchdev port attribute notifier structures, and converts drivers to not look at this member. In part, this patch contains a revert of my previous commit 2e554a7a5d8a ("net: dsa: propagate switchdev vlan_filtering prepare phase to drivers"). For the most part, the conversion was trivial except for: - Rocker's world implementation based on Broadcom OF-DPA had an odd implementation of ofdpa_port_attr_bridge_flags_set. The conversion was done mechanically, by pasting the implementation twice, then only keeping the code that would get executed during prepare phase on top, then only keeping the code that gets executed during the commit phase on bottom, then simplifying the resulting code until this was obtained. - DSA's offloading of STP state, bridge flags, VLAN filtering and multicast router could be converted right away. But the ageing time could not, so a shim was introduced and this was left for a further commit. Signed-off-by: Vladimir Oltean Acked-by: Linus Walleij Acked-by: Jiri Pirko Reviewed-by: Kurt Kanzenbach # hellcreek Reviewed-by: Linus Walleij # RTL8366RB Reviewed-by: Ido Schimmel Reviewed-by: Florian Fainelli Signed-off-by: Jakub Kicinski