net: partial revert of the "Make timestamping selectable: series

Revert following commits:

commit acec05fb78ab ("net_tstamp: Add TIMESTAMPING SOFTWARE and HARDWARE mask")
commit 11d55be06df0 ("net: ethtool: Add a command to expose current time stamping layer")
commit bb8645b00ced ("netlink: specs: Introduce new netlink command to get current timestamp")
commit d905f9c75329 ("net: ethtool: Add a command to list available time stamping layers")
commit aed5004ee7a0 ("netlink: specs: Introduce new netlink command to list available time stamping layers")
commit 51bdf3165f01 ("net: Replace hwtstamp_source by timestamping layer")
commit 0f7f463d4821 ("net: Change the API of PHY default timestamp to MAC")
commit 091fab122869 ("net: ethtool: ts: Update GET_TS to reply the current selected timestamp")
commit 152c75e1d002 ("net: ethtool: ts: Let the active time stamping layer be selectable")
commit ee60ea6be0d3 ("netlink: specs: Introduce time stamping set command")

They need more time for reviews.

Link: https://lore.kernel.org/all/20231118183529.6e67100c@kernel.org/
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

3 files changed, 14 insertions, 35 deletions

diff --git a/net/core/dev.c b/net/core/dev.c
index 05ce00632892..af53f6d838ce 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -10212,9 +10212,6 @@ int register_netdevice(struct net_device *dev)
 	    dev->rtnl_link_state == RTNL_LINK_INITIALIZED)
 		rtmsg_ifinfo(RTM_NEWLINK, dev, ~0U, GFP_KERNEL, 0, NULL);
 
-	if (dev->ethtool_ops->get_ts_info)
-		dev->ts_layer = MAC_TIMESTAMPING;
-
 out:
 	return ret;
 
diff --git a/net/core/dev_ioctl.c b/net/core/dev_ioctl.c
index bc8be9749376..9a66cf5015f2 100644
--- a/net/core/dev_ioctl.c
+++ b/net/core/dev_ioctl.c
@@ -259,7 +259,9 @@ static int dev_eth_ioctl(struct net_device *dev,
  * @dev: Network device
  * @cfg: Timestamping configuration structure
  *
- * Helper for calling the selected hardware provider timestamping.
+ * Helper for enforcing a common policy that phylib timestamping, if available,
+ * should take precedence in front of hardware timestamping provided by the
+ * netdev.
  *
  * Note: phy_mii_ioctl() only handles SIOCSHWTSTAMP (not SIOCGHWTSTAMP), and
  * there only exists a phydev->mii_ts->hwtstamp() method. So this will return
@@ -269,14 +271,10 @@ static int dev_eth_ioctl(struct net_device *dev,
 static int dev_get_hwtstamp_phylib(struct net_device *dev,
 				   struct kernel_hwtstamp_config *cfg)
 {
-	enum timestamping_layer ts_layer = dev->ts_layer;
-
-	if (ts_layer == PHY_TIMESTAMPING)
+	if (phy_has_hwtstamp(dev->phydev))
 		return phy_hwtstamp_get(dev->phydev, cfg);
-	else if (ts_layer == MAC_TIMESTAMPING)
-		return dev->netdev_ops->ndo_hwtstamp_get(dev, cfg);
 
-	return -EOPNOTSUPP;
+	return dev->netdev_ops->ndo_hwtstamp_get(dev, cfg);
 }
 
 static int dev_get_hwtstamp(struct net_device *dev, struct ifreq *ifr)
@@ -317,8 +315,9 @@ static int dev_get_hwtstamp(struct net_device *dev, struct ifreq *ifr)
  * @cfg: Timestamping configuration structure
  * @extack: Netlink extended ack message structure, for error reporting
  *
- * Helper for calling the selected hardware provider timestamping.
- * If the netdev driver needs to perform specific actions even for PHY
+ * Helper for enforcing a common policy that phylib timestamping, if available,
+ * should take precedence in front of hardware timestamping provided by the
+ * netdev. If the netdev driver needs to perform specific actions even for PHY
  * timestamping to work properly (a switch port must trap the timestamped
  * frames and not forward them), it must set IFF_SEE_ALL_HWTSTAMP_REQUESTS in
  * dev->priv_flags.
@@ -328,26 +327,20 @@ int dev_set_hwtstamp_phylib(struct net_device *dev,
 			    struct netlink_ext_ack *extack)
 {
 	const struct net_device_ops *ops = dev->netdev_ops;
-	enum timestamping_layer ts_layer = dev->ts_layer;
+	bool phy_ts = phy_has_hwtstamp(dev->phydev);
 	struct kernel_hwtstamp_config old_cfg = {};
 	bool changed = false;
 	int err;
 
-	cfg->source = ts_layer;
-
-	if (ts_layer != PHY_TIMESTAMPING &&
-	    ts_layer != MAC_TIMESTAMPING)
-		return -EOPNOTSUPP;
+	cfg->source = phy_ts ? HWTSTAMP_SOURCE_PHYLIB : HWTSTAMP_SOURCE_NETDEV;
 
-	if (ts_layer == PHY_TIMESTAMPING &&
-	    dev->priv_flags & IFF_SEE_ALL_HWTSTAMP_REQUESTS) {
+	if (phy_ts && (dev->priv_flags & IFF_SEE_ALL_HWTSTAMP_REQUESTS)) {
 		err = ops->ndo_hwtstamp_get(dev, &old_cfg);
 		if (err)
 			return err;
 	}
 
-	if (ts_layer == MAC_TIMESTAMPING ||
-	    dev->priv_flags & IFF_SEE_ALL_HWTSTAMP_REQUESTS) {
+	if (!phy_ts || (dev->priv_flags & IFF_SEE_ALL_HWTSTAMP_REQUESTS)) {
 		err = ops->ndo_hwtstamp_set(dev, cfg, extack);
 		if (err) {
 			if (extack->_msg)
@@ -356,11 +349,10 @@ int dev_set_hwtstamp_phylib(struct net_device *dev,
 		}
 	}
 
-	if (ts_layer == PHY_TIMESTAMPING &&
-	    dev->priv_flags & IFF_SEE_ALL_HWTSTAMP_REQUESTS)
+	if (phy_ts && (dev->priv_flags & IFF_SEE_ALL_HWTSTAMP_REQUESTS))
 		changed = kernel_hwtstamp_config_changed(&old_cfg, cfg);
 
-	if (ts_layer == PHY_TIMESTAMPING) {
+	if (phy_ts) {
 		err = phy_hwtstamp_set(dev->phydev, cfg, extack);
 		if (err) {
 			if (changed)
diff --git a/net/core/timestamping.c b/net/core/timestamping.c
index 5cf51a523fb3..04840697fe79 100644
--- a/net/core/timestamping.c
+++ b/net/core/timestamping.c
@@ -21,7 +21,6 @@ static unsigned int classify(const struct sk_buff *skb)
 
 void skb_clone_tx_timestamp(struct sk_buff *skb)
 {
-	enum timestamping_layer ts_layer;
 	struct mii_timestamper *mii_ts;
 	struct sk_buff *clone;
 	unsigned int type;
@@ -29,10 +28,6 @@ void skb_clone_tx_timestamp(struct sk_buff *skb)
 	if (!skb->sk)
 		return;
 
-	ts_layer = skb->dev->ts_layer;
-	if (ts_layer != PHY_TIMESTAMPING)
-		return;
-
 	type = classify(skb);
 	if (type == PTP_CLASS_NONE)
 		return;
@@ -49,17 +44,12 @@ EXPORT_SYMBOL_GPL(skb_clone_tx_timestamp);
 
 bool skb_defer_rx_timestamp(struct sk_buff *skb)
 {
-	enum timestamping_layer ts_layer;
 	struct mii_timestamper *mii_ts;
 	unsigned int type;
 
 	if (!skb->dev || !skb->dev->phydev || !skb->dev->phydev->mii_ts)
 		return false;
 
-	ts_layer = skb->dev->ts_layer;
-	if (ts_layer != PHY_TIMESTAMPING)
-		return false;
-
 	if (skb_headroom(skb) < ETH_HLEN)
 		return false;