Merge branch 'dsa_master_ioctl-notifier'

Vladimir Oltean says:

====================
net: Convert dsa_master_ioctl() to netdev notifier

This is preparatory work in order for Maxim Georgiev to be able to start
the API conversion process of hardware timestamping from ndo_eth_ioctl()
to ndo_hwtstamp_set():
https://lore.kernel.org/netdev/20230331045619.40256-1-glipus@gmail.com/

In turn, Maxim Georgiev's work is a preparation so that Köry Maincent is
able to make the active hardware timestamping layer selectable by user
space.
https://lore.kernel.org/netdev/20230308135936.761794-1-kory.maincent@bootlin.com/

So, quite some dependency chain.

Before this patch set, DSA prevented the conversion of any networking
driver from the ndo_eth_ioctl() API to the ndo_hwtstamp_set() API,
because it wanted to validate the hwtstamping settings on the DSA
master, and it was only coded up to do this using the old API.

After this patch set, a new netdev notifier exists, which does not
depend on anything that would constitute the "soon-to-be-legacy" API,
but rather, it uses a newly introduced struct kernel_hwtstamp_config,
and it doesn't issue any ioctl at all, being thus compatible both with
ndo_eth_ioctl(), and with the not-yet-introduced, but now possible,
ndo_hwtstamp_set().
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

5 files changed, 36 insertions, 40 deletions

diff --git a/net/dsa/master.c b/net/dsa/master.c
index 22d3f16b0e6d..c2cabe6248b1 100644
--- a/net/dsa/master.c
+++ b/net/dsa/master.c
@@ -195,38 +195,31 @@ static void dsa_master_get_strings(struct net_device *dev, uint32_t stringset,
 	}
 }
 
-static int dsa_master_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
+/* Deny PTP operations on master if there is at least one switch in the tree
+ * that is PTP capable.
+ */
+int dsa_master_pre_change_hwtstamp(struct net_device *dev,
+				   const struct kernel_hwtstamp_config *config,
+				   struct netlink_ext_ack *extack)
 {
 	struct dsa_port *cpu_dp = dev->dsa_ptr;
 	struct dsa_switch *ds = cpu_dp->ds;
 	struct dsa_switch_tree *dst;
-	int err = -EOPNOTSUPP;
 	struct dsa_port *dp;
 
 	dst = ds->dst;
 
-	switch (cmd) {
-	case SIOCGHWTSTAMP:
-	case SIOCSHWTSTAMP:
-		/* Deny PTP operations on master if there is at least one
-		 * switch in the tree that is PTP capable.
-		 */
-		list_for_each_entry(dp, &dst->ports, list)
-			if (dsa_port_supports_hwtstamp(dp, ifr))
-				return -EBUSY;
-		break;
+	list_for_each_entry(dp, &dst->ports, list) {
+		if (dsa_port_supports_hwtstamp(dp)) {
+			NL_SET_ERR_MSG(extack,
+				       "HW timestamping not allowed on DSA master when switch supports the operation");
+			return -EBUSY;
+		}
 	}
 
-	if (dev->netdev_ops->ndo_eth_ioctl)
-		err = dev->netdev_ops->ndo_eth_ioctl(dev, ifr, cmd);
-
-	return err;
+	return 0;
 }
 
-static const struct dsa_netdevice_ops dsa_netdev_ops = {
-	.ndo_eth_ioctl = dsa_master_ioctl,
-};
-
 static int dsa_master_ethtool_setup(struct net_device *dev)
 {
 	struct dsa_port *cpu_dp = dev->dsa_ptr;
@@ -267,15 +260,6 @@ static void dsa_master_ethtool_teardown(struct net_device *dev)
 	cpu_dp->orig_ethtool_ops = NULL;
 }
 
-static void dsa_netdev_ops_set(struct net_device *dev,
-			       const struct dsa_netdevice_ops *ops)
-{
-	if (netif_is_lag_master(dev))
-		return;
-
-	dev->dsa_ptr->netdev_ops = ops;
-}
-
 /* Keep the master always promiscuous if the tagging protocol requires that
  * (garbles MAC DA) or if it doesn't support unicast filtering, case in which
  * it would revert to promiscuous mode as soon as we call dev_uc_add() on it
@@ -414,16 +398,13 @@ int dsa_master_setup(struct net_device *dev, struct dsa_port *cpu_dp)
 	if (ret)
 		goto out_err_reset_promisc;
 
-	dsa_netdev_ops_set(dev, &dsa_netdev_ops);
-
 	ret = sysfs_create_group(&dev->dev.kobj, &dsa_group);
 	if (ret)
-		goto out_err_ndo_teardown;
+		goto out_err_ethtool_teardown;
 
 	return ret;
 
-out_err_ndo_teardown:
-	dsa_netdev_ops_set(dev, NULL);
+out_err_ethtool_teardown:
 	dsa_master_ethtool_teardown(dev);
 out_err_reset_promisc:
 	dsa_master_set_promiscuity(dev, -1);
@@ -433,7 +414,6 @@ out_err_reset_promisc:
 void dsa_master_teardown(struct net_device *dev)
 {
 	sysfs_remove_group(&dev->dev.kobj, &dsa_group);
-	dsa_netdev_ops_set(dev, NULL);
 	dsa_master_ethtool_teardown(dev);
 	dsa_master_reset_mtu(dev);
 	dsa_master_set_promiscuity(dev, -1);
diff --git a/net/dsa/master.h b/net/dsa/master.h
index 3fc0e610b5b5..80842f4e27f7 100644
--- a/net/dsa/master.h
+++ b/net/dsa/master.h
@@ -15,5 +15,8 @@ int dsa_master_lag_setup(struct net_device *lag_dev, struct dsa_port *cpu_dp,
 			 struct netlink_ext_ack *extack);
 void dsa_master_lag_teardown(struct net_device *lag_dev,
 			     struct dsa_port *cpu_dp);
+int dsa_master_pre_change_hwtstamp(struct net_device *dev,
+				   const struct kernel_hwtstamp_config *config,
+				   struct netlink_ext_ack *extack);
 
 #endif
diff --git a/net/dsa/port.c b/net/dsa/port.c
index 15cee17769e9..71ba30538411 100644
--- a/net/dsa/port.c
+++ b/net/dsa/port.c
@@ -114,19 +114,21 @@ static bool dsa_port_can_configure_learning(struct dsa_port *dp)
 	return !err;
 }
 
-bool dsa_port_supports_hwtstamp(struct dsa_port *dp, struct ifreq *ifr)
+bool dsa_port_supports_hwtstamp(struct dsa_port *dp)
 {
 	struct dsa_switch *ds = dp->ds;
+	struct ifreq ifr = {};
 	int err;
 
 	if (!ds->ops->port_hwtstamp_get || !ds->ops->port_hwtstamp_set)
 		return false;
 
 	/* "See through" shim implementations of the "get" method.
-	 * This will clobber the ifreq structure, but we will either return an
-	 * error, or the master will overwrite it with proper values.
+	 * Since we can't cook up a complete ioctl request structure, this will
+	 * fail in copy_to_user() with -EFAULT, which hopefully is enough to
+	 * detect a valid implementation.
 	 */
-	err = ds->ops->port_hwtstamp_get(ds, dp->index, ifr);
+	err = ds->ops->port_hwtstamp_get(ds, dp->index, &ifr);
 	return err != -EOPNOTSUPP;
 }
 
diff --git a/net/dsa/port.h b/net/dsa/port.h
index 9c218660d223..dc812512fd0e 100644
--- a/net/dsa/port.h
+++ b/net/dsa/port.h
@@ -15,7 +15,7 @@ struct switchdev_obj_port_mdb;
 struct switchdev_vlan_msti;
 struct phy_device;
 
-bool dsa_port_supports_hwtstamp(struct dsa_port *dp, struct ifreq *ifr);
+bool dsa_port_supports_hwtstamp(struct dsa_port *dp);
 void dsa_port_set_tag_protocol(struct dsa_port *cpu_dp,
 			       const struct dsa_device_ops *tag_ops);
 int dsa_port_set_state(struct dsa_port *dp, u8 state, bool do_fast_age);
diff --git a/net/dsa/slave.c b/net/dsa/slave.c
index 165bb2cb8431..8abc1658ac47 100644
--- a/net/dsa/slave.c
+++ b/net/dsa/slave.c
@@ -3289,6 +3289,7 @@ static int dsa_master_changeupper(struct net_device *dev,
 static int dsa_slave_netdevice_event(struct notifier_block *nb,
 				     unsigned long event, void *ptr)
 {
+	struct netlink_ext_ack *extack = netdev_notifier_info_to_extack(ptr);
 	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
 
 	switch (event) {
@@ -3418,6 +3419,16 @@ static int dsa_slave_netdevice_event(struct notifier_block *nb,
 
 		return NOTIFY_OK;
 	}
+	case NETDEV_PRE_CHANGE_HWTSTAMP: {
+		struct netdev_notifier_hwtstamp_info *info = ptr;
+		int err;
+
+		if (!netdev_uses_dsa(dev))
+			return NOTIFY_DONE;
+
+		err = dsa_master_pre_change_hwtstamp(dev, info->config, extack);
+		return notifier_from_errno(err);
+	}
 	default:
 		break;
 	}