kernel/linux.git/net/dsa/master.c, branch v6.6.131

net: dsa: replace NETDEV_PRE_CHANGE_HWTSTAMP notifier with a stub

2023-04-09T14:35:49+00:00

There was a sort of rush surrounding commit 88c0a6b503b7 ("net: create a netdev notifier for DSA to reject PTP on DSA master"), due to a desire to convert DSA's attempt to deny TX timestamping on a DSA master to something that doesn't block the kernel-wide API conversion from ndo_eth_ioctl() to ndo_hwtstamp_set(). What was required was a mechanism that did not depend on ndo_eth_ioctl(), and what was provided was a mechanism that did not depend on ndo_eth_ioctl(), while at the same time introducing something that wasn't absolutely necessary - a new netdev notifier. There have been objections from Jakub Kicinski that using notifiers in general when they are not absolutely necessary creates complications to the control flow and difficulties to maintainers who look at the code. So there is a desire to not use notifiers. In addition to that, the notifier chain gets called even if there is no DSA in the system and no one is interested in applying any restriction. Take the model of udp_tunnel_nic_ops and introduce a stub mechanism, through which net/core/dev_ioctl.c can call into DSA even when CONFIG_NET_DSA=m. Compared to the code that existed prior to the notifier conversion, aka what was added in commits: - 4cfab3566710 ("net: dsa: Add wrappers for overloaded ndo_ops") - 3369afba1e46 ("net: Call into DSA netdevice_ops wrappers") this is different because we are not overloading any struct net_device_ops of the DSA master anymore, but rather, we are exposing a rather specific functionality which is orthogonal to which API is used to enable it - ndo_eth_ioctl() or ndo_hwtstamp_set(). Also, what is similar is that both approaches use function pointers to get from built-in code to DSA. There is no point in replicating the function pointers towards __dsa_master_hwtstamp_validate() once for every CPU port (dev->dsa_ptr). Instead, it is sufficient to introduce a singleton struct dsa_stubs, built into the kernel, which contains a single function pointer to __dsa_master_hwtstamp_validate(). I find this approach preferable to what we had originally, because dev->dsa_ptr->netdev_ops->ndo_do_ioctl() used to require going through struct dsa_port (dev->dsa_ptr), and so, this was incompatible with any attempts to add any data encapsulation and hide DSA data structures from the outside world. Link: https://lore.kernel.org/netdev/20230403083019.120b72fd@kernel.org/ Signed-off-by: Vladimir Oltean Reviewed-by: Florian Fainelli Signed-off-by: David S. Miller

net: create a netdev notifier for DSA to reject PTP on DSA master

2023-04-03T09:04:27+00:00

The fact that PTP 2-step TX timestamping is broken on DSA switches if the master also timestamps the same packets is documented by commit f685e609a301 ("net: dsa: Deny PTP on master if switch supports it"). We attempt to help the users avoid shooting themselves in the foot by making DSA reject the timestamping ioctls on an interface that is a DSA master, and the switch tree beneath it contains switches which are aware of PTP. The only problem is that there isn't an established way of intercepting ndo_eth_ioctl calls, so DSA creates avoidable burden upon the network stack by creating a struct dsa_netdevice_ops with overlaid function pointers that are manually checked from the relevant call sites. There used to be 2 such dsa_netdevice_ops, but now, ndo_eth_ioctl is the only one left. There is an ongoing effort to migrate driver-visible hardware timestamping control from the ndo_eth_ioctl() based API to a new ndo_hwtstamp_set() model, but DSA actively prevents that migration, since dsa_master_ioctl() is currently coded to manually call the master's legacy ndo_eth_ioctl(), and so, whenever a network device driver would be converted to the new API, DSA's restrictions would be circumvented, because any device could be used as a DSA master. The established way for unrelated modules to react on a net device event is via netdevice notifiers. So we create a new notifier which gets called whenever there is an attempt to change hardware timestamping settings on a device. Finally, there is another reason why a netdev notifier will be a good idea, besides strictly DSA, and this has to do with PHY timestamping. With ndo_eth_ioctl(), all MAC drivers must manually call phy_has_hwtstamp() before deciding whether to act upon SIOCSHWTSTAMP, otherwise they must pass this ioctl to the PHY driver via phy_mii_ioctl(). With the new ndo_hwtstamp_set() API, it will be desirable to simply not make any calls into the MAC device driver when timestamping should be performed at the PHY level. But there exist drivers, such as the lan966x switch, which need to install packet traps for PTP regardless of whether they are the layer that provides the hardware timestamps, or the PHY is. That would be impossible to support with the new API. The proposal there, too, is to introduce a netdev notifier which acts as a better cue for switching drivers to add or remove PTP packet traps, than ndo_hwtstamp_set(). The one introduced here "almost" works there as well, except for the fact that packet traps should only be installed if the PHY driver succeeded to enable hardware timestamping, whereas here, we need to deny hardware timestamping on the DSA master before it actually gets enabled. This is why this notifier is called "PRE_", and the notifier that would get used for PHY timestamping and packet traps would be called NETDEV_CHANGE_HWTSTAMP. This isn't a new concept, for example NETDEV_CHANGEUPPER and NETDEV_PRECHANGEUPPER do the same thing. In expectation of future netlink UAPI, we also pass a non-NULL extack pointer to the netdev notifier, and we make DSA populate it with an informative reason for the rejection. To avoid making it go to waste, we make the ioctl-based dev_set_hwtstamp() create a fake extack and print the message to the kernel log. Link: https://lore.kernel.org/netdev/20230401191215.tvveoi3lkawgg6g4@skbuf/ Link: https://lore.kernel.org/netdev/20230310164451.ls7bbs6pdzs4m6pw@skbuf/ Signed-off-by: Vladimir Oltean Reviewed-by: Florian Fainelli Signed-off-by: David S. Miller

net: dsa: make dsa_port_supports_hwtstamp() construct a fake ifreq

2023-04-03T09:04:27+00:00

dsa_master_ioctl() is in the process of getting converted to a different API, where we won't have access to a struct ifreq * anymore, but rather, to a struct kernel_hwtstamp_config. Since ds->ops->port_hwtstamp_get() still uses struct ifreq *, this creates a difficult situation where we have to make up such a dummy pointer. The conversion is a bit messy, because it forces a "good" implementation of ds->ops->port_hwtstamp_get() to return -EFAULT in copy_to_user() because of the NULL ifr->ifr_data pointer. However, it works, and it is only a transient step until ds->ops->port_hwtstamp_get() gets converted to the new API which passes struct kernel_hwtstamp_config and does not call copy_to_user(). Signed-off-by: Vladimir Oltean Reviewed-by: Florian Fainelli Signed-off-by: David S. Miller

net: dsa: Use sysfs_emit() to instead of sprintf()

2023-02-02T14:28:59+00:00

Follow the advice of the Documentation/filesystems/sysfs.rst and show() should only use sysfs_emit() or sysfs_emit_at() when formatting the value to be returned to user space. Signed-off-by: Bo Liu Link: https://lore.kernel.org/r/20230201081438.3151-1-liubo03@inspur.com Signed-off-by: Paolo Abeni

netlink: provide an ability to set default extack message

2023-02-02T05:04:09+00:00

In netdev common pattern, extack pointer is forwarded to the drivers to be filled with error message. However, the caller can easily overwrite the filled message. Instead of adding multiple "if (!extack->_msg)" checks before any NL_SET_ERR_MSG() call, which appears after call to the driver, let's add new macro to common code. [1] https://lore.kernel.org/all/Y9Irgrgf3uxOjwUm@unreal Reviewed-by: Simon Horman Reviewed-by: Nikolay Aleksandrov Signed-off-by: Leon Romanovsky Link: https://lore.kernel.org/r/6993fac557a40a1973dfa0095107c3d03d40bec1.1675171790.git.leon@kernel.org Signed-off-by: Jakub Kicinski

net: dsa: rename dsa2.c back into dsa.c and create its header

2022-11-23T04:41:53+00:00

The previous change moved the code into the larger file (dsa2.c) to minimize the delta. Rename that now to dsa.c, and create dsa.h, where all related definitions from dsa_priv.h go. Signed-off-by: Vladimir Oltean Reviewed-by: Florian Fainelli Signed-off-by: Jakub Kicinski

net: dsa: move tagging protocol code to tag.{c,h}

2022-11-23T04:41:50+00:00

It would be nice if tagging protocol drivers could include just the header they need, since they are (mostly) data path and isolated from most of the other DSA core code does. Create a tag.c and a tag.h file which are meant to support tagging protocol drivers. Signed-off-by: Vladimir Oltean Reviewed-by: Florian Fainelli Signed-off-by: Jakub Kicinski

net: dsa: move headers exported by master.c to master.h

2022-11-23T04:41:49+00:00

Minimize the use of the bloated dsa_priv.h by moving the prototypes exported by master.c to their own header file. Signed-off-by: Vladimir Oltean Reviewed-by: Florian Fainelli Signed-off-by: Jakub Kicinski

net: dsa: move headers exported by port.c to port.h

2022-11-23T04:41:48+00:00

Minimize the use of the bloated dsa_priv.h by moving the prototypes exported by port.c to their own header file. Signed-off-by: Vladimir Oltean Reviewed-by: Florian Fainelli Signed-off-by: Jakub Kicinski

net: dsa: autoload tag driver module on tagging protocol change

2022-11-18T05:16:42+00:00

Issue a request_module() call when an attempt to change the tagging protocol is made, either by sysfs or by device tree. In the case of ocelot (the only driver for which the default and the alternative tagging protocol are compiled as different modules), the user is now no longer required to insert tag_ocelot_8021q.ko manually. In the particular case of ocelot, this solves a problem where tag_ocelot_8021q.ko is built as module, and this is present in the device tree: &mscc_felix_port4 { dsa-tag-protocol = "ocelot-8021q"; }; &mscc_felix_port5 { dsa-tag-protocol = "ocelot-8021q"; }; Because no one attempts to load the module into the kernel at boot time, the switch driver will fail to probe (actually forever defer) until someone manually inserts tag_ocelot_8021q.ko. This is now no longer necessary and happens automatically. Rename dsa_find_tagger_by_name() to denote the change in functionality: there is now feature parity with dsa_tag_driver_get_by_id(), i.o.w. we also load the module if it's missing. Link: https://lore.kernel.org/lkml/20221027113248.420216-1-michael@walle.cc/ Suggested-by: Michael Walle Signed-off-by: Vladimir Oltean Tested-by: Michael Walle # on kontron-sl28 w/ ocelot_8021q Tested-by: Michael Walle Signed-off-by: Jakub Kicinski