summaryrefslogtreecommitdiff
path: root/net/core
diff options
context:
space:
mode:
authorVladimir Oltean <vladimir.oltean@nxp.com>2023-04-02 15:37:55 +0300
committerDavid S. Miller <davem@davemloft.net>2023-04-03 10:04:27 +0100
commit88c0a6b503b7f4fffb68a8d49c3987870c5b1d6b (patch)
treee59030b8a2b0657651f7b0528d270f0d2d585a72 /net/core
parentff6ac4d013e680a5e7a38ee83ca59ffe1846915d (diff)
net: create a netdev notifier for DSA to reject PTP on DSA master
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 <vladimir.oltean@nxp.com> Reviewed-by: Florian Fainelli <f.fainelli@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/core')
-rw-r--r--net/core/dev.c8
-rw-r--r--net/core/dev_ioctl.c16
2 files changed, 17 insertions, 7 deletions
diff --git a/net/core/dev.c b/net/core/dev.c
index 0c4b21291348..7ce5985be84b 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -160,8 +160,6 @@ struct list_head ptype_base[PTYPE_HASH_SIZE] __read_mostly;
struct list_head ptype_all __read_mostly; /* Taps */
static int netif_rx_internal(struct sk_buff *skb);
-static int call_netdevice_notifiers_info(unsigned long val,
- struct netdev_notifier_info *info);
static int call_netdevice_notifiers_extack(unsigned long val,
struct net_device *dev,
struct netlink_ext_ack *extack);
@@ -1614,7 +1612,7 @@ const char *netdev_cmd_to_name(enum netdev_cmd cmd)
N(SVLAN_FILTER_PUSH_INFO) N(SVLAN_FILTER_DROP_INFO)
N(PRE_CHANGEADDR) N(OFFLOAD_XSTATS_ENABLE) N(OFFLOAD_XSTATS_DISABLE)
N(OFFLOAD_XSTATS_REPORT_USED) N(OFFLOAD_XSTATS_REPORT_DELTA)
- N(XDP_FEAT_CHANGE)
+ N(XDP_FEAT_CHANGE) N(PRE_CHANGE_HWTSTAMP)
}
#undef N
return "UNKNOWN_NETDEV_EVENT";
@@ -1919,8 +1917,8 @@ static void move_netdevice_notifiers_dev_net(struct net_device *dev,
* are as for raw_notifier_call_chain().
*/
-static int call_netdevice_notifiers_info(unsigned long val,
- struct netdev_notifier_info *info)
+int call_netdevice_notifiers_info(unsigned long val,
+ struct netdev_notifier_info *info)
{
struct net *net = dev_net(info->dev);
int ret;
diff --git a/net/core/dev_ioctl.c b/net/core/dev_ioctl.c
index c532ef4d5dff..6d772837eb3f 100644
--- a/net/core/dev_ioctl.c
+++ b/net/core/dev_ioctl.c
@@ -259,7 +259,11 @@ static int dev_get_hwtstamp(struct net_device *dev, struct ifreq *ifr)
static int dev_set_hwtstamp(struct net_device *dev, struct ifreq *ifr)
{
+ struct netdev_notifier_hwtstamp_info info = {
+ .info.dev = dev,
+ };
struct kernel_hwtstamp_config kernel_cfg;
+ struct netlink_ext_ack extack = {};
struct hwtstamp_config cfg;
int err;
@@ -272,9 +276,17 @@ static int dev_set_hwtstamp(struct net_device *dev, struct ifreq *ifr)
if (err)
return err;
- err = dsa_ndo_eth_ioctl(dev, ifr, SIOCSHWTSTAMP);
- if (err != -EOPNOTSUPP)
+ info.info.extack = &extack;
+ info.config = &kernel_cfg;
+
+ err = call_netdevice_notifiers_info(NETDEV_PRE_CHANGE_HWTSTAMP,
+ &info.info);
+ err = notifier_to_errno(err);
+ if (err) {
+ if (extack._msg)
+ netdev_err(dev, "%s\n", extack._msg);
return err;
+ }
return dev_eth_ioctl(dev, ifr, SIOCSHWTSTAMP);
}