[PATCH RFC V1 net-next 3/4] net: Let the active time stamping layer be selectable.

Richard Cochran
2022-01-03T23:26:10Z

Make the sysfs knob writable, and add checks in the ioctl and time
stamping paths to respect the currently selected time stamping layer.

Signed-off-by: Richard Cochran <richardcochran@gmail.com>
---
.../ABI/testing/sysfs-class-net-timestamping | 5 +-
net/core/dev_ioctl.c | 44 ++++++++++++++--
net/core/net-sysfs.c | 50 +++++++++++++++++--
net/core/timestamping.c | 6 +++
net/ethtool/common.c | 18 +++++--
5 files changed, 111 insertions(+), 12 deletions(-)

diff --git a/Documentation/ABI/testing/sysfs-class-net-timestamping b/Documentation/ABI/testing/sysfs-class-net-timestamping
index 529c3a6eb607..6dfd59740cad 100644
--- a/Documentation/ABI/testing/sysfs-class-net-timestamping
+++ b/Documentation/ABI/testing/sysfs-class-net-timestamping
@@ -11,7 +11,10 @@ What: /sys/class/net/<iface>/current_timestamping_provider
Date: January 2022
Contact: Richard Cochran <richardcochran@gmail.com>
Description:
- Show the current SO_TIMESTAMPING provider.
+ Shows or sets the current SO_TIMESTAMPING provider.
+ When changing the value, some packets in the kernel
+ networking stack may still be delivered with time
+ stamps from the previous provider.
The possible values are:
- "mac" The MAC provides time stamping.
- "phy" The PHY or MII device provides time stamping.
diff --git a/net/core/dev_ioctl.c b/net/core/dev_ioctl.c
index 1b807d119da5..269068ce3a51 100644
--- a/net/core/dev_ioctl.c
+++ b/net/core/dev_ioctl.c
@@ -260,6 +260,43 @@ static int dev_eth_ioctl(struct net_device *dev,
return err;
}

+static int dev_hwtstamp_ioctl(struct net_device *dev,
+ struct ifreq *ifr, unsigned int cmd)
+{
+ const struct net_device_ops *ops = dev->netdev_ops;
+ int err;
+
+ err = dsa_ndo_eth_ioctl(dev, ifr, cmd);
+ if (err == 0 || err != -EOPNOTSUPP)
+ return err;
+
+ if (!netif_device_present(dev))
+ return -ENODEV;
+
+ switch (dev->selected_timestamping_layer) {
+
+ case MAC_TIMESTAMPING:
+ if (ops->ndo_do_ioctl == phy_do_ioctl) {
+ /* Some drivers set .ndo_do_ioctl to phy_do_ioctl. */
+ err = -EOPNOTSUPP;
+ } else {
+ err = ops->ndo_eth_ioctl(dev, ifr, cmd);
+ }
+ break;
+
+ case PHY_TIMESTAMPING:
+ if (phy_has_hwtstamp(dev->phydev)) {
+ err = phy_mii_ioctl(dev->phydev, ifr, cmd);
+ } else {
+ err = -ENODEV;
+ WARN_ON(1);
+ }
+ break;
+ }
+
+ return err;
+}
+
static int dev_siocbond(struct net_device *dev,
struct ifreq *ifr, unsigned int cmd)
{
@@ -395,6 +432,9 @@ static int dev_ifsioc(struct net *net, struct ifreq *ifr, void __user *data,
return err;
fallthrough;

+ case SIOCGHWTSTAMP:
+ return dev_hwtstamp_ioctl(dev, ifr, cmd);
+
/*
* Unknown or private ioctl
*/
@@ -405,9 +445,7 @@ static int dev_ifsioc(struct net *net, struct ifreq *ifr, void __user *data,

if (cmd == SIOCGMIIPHY ||
cmd == SIOCGMIIREG ||
- cmd == SIOCSMIIREG ||
- cmd == SIOCSHWTSTAMP ||
- cmd == SIOCGHWTSTAMP) {
+ cmd == SIOCSMIIREG) {
err = dev_eth_ioctl(dev, ifr, cmd);
} else if (cmd == SIOCBONDENSLAVE ||
cmd == SIOCBONDRELEASE ||
diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index 4ff7ef417c38..c27f01a1a285 100644
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -664,17 +664,59 @@ static ssize_t current_timestamping_provider_show(struct device *dev,
if (!rtnl_trylock())
return restart_syscall();

- if (phy_has_tsinfo(phydev)) {
- ret = sprintf(buf, "%s\n", "phy");
- } else {
+ switch (netdev->selected_timestamping_layer) {
+ case MAC_TIMESTAMPING:
ret = sprintf(buf, "%s\n", "mac");
+ break;
+ case PHY_TIMESTAMPING:
+ ret = sprintf(buf, "%s\n", "phy");
+ break;
}

rtnl_unlock();

return ret;
}
-static DEVICE_ATTR_RO(current_timestamping_provider);
+
+static ssize_t current_timestamping_provider_store(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t len)
+{
+ struct net_device *netdev = to_net_dev(dev);
+ struct net *net = dev_net(netdev);
+ enum timestamping_layer flavor;
+
+ if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
+ return -EPERM;
+
+ if (!strcmp(buf, "mac\n"))
+ flavor = MAC_TIMESTAMPING;
+ else if (!strcmp(buf, "phy\n"))
+ flavor = PHY_TIMESTAMPING;
+ else
+ return -EINVAL;
+
+ if (!rtnl_trylock())
+ return restart_syscall();
+
+ if (!dev_isalive(netdev))
+ goto out;
+
+ if (netdev->selected_timestamping_layer != flavor) {
+ const struct net_device_ops *ops = netdev->netdev_ops;
+ struct ifreq ifr = {0};
+
+ /* Disable time stamping in the current layer. */
+ if (netif_device_present(netdev) && ops->ndo_eth_ioctl)
+ ops->ndo_eth_ioctl(netdev, &ifr, SIOCSHWTSTAMP);
+
+ netdev->selected_timestamping_layer = flavor;
+ }
+out:
+ rtnl_unlock();
+ return len;
+}
+static DEVICE_ATTR_RW(current_timestamping_provider);

static struct attribute *net_class_attrs[] __ro_after_init = {
&dev_attr_netdev_group.attr,
diff --git a/net/core/timestamping.c b/net/core/timestamping.c
index 04840697fe79..31c3142787b7 100644
--- a/net/core/timestamping.c
+++ b/net/core/timestamping.c
@@ -28,6 +28,9 @@ void skb_clone_tx_timestamp(struct sk_buff *skb)
if (!skb->sk)
return;

+ if (skb->dev->selected_timestamping_layer != PHY_TIMESTAMPING)
+ return;
+
type = classify(skb);
if (type == PTP_CLASS_NONE)
return;
@@ -50,6 +53,9 @@ bool skb_defer_rx_timestamp(struct sk_buff *skb)
if (!skb->dev || !skb->dev->phydev || !skb->dev->phydev->mii_ts)
return false;

+ if (skb->dev->selected_timestamping_layer != PHY_TIMESTAMPING)
+ return false;
+
if (skb_headroom(skb) < ETH_HLEN)
return false;

diff --git a/net/ethtool/common.c b/net/ethtool/common.c
index 651d18eef589..7b50820c1d1d 100644
--- a/net/ethtool/common.c
+++ b/net/ethtool/common.c
@@ -545,10 +545,20 @@ int __ethtool_get_ts_info(struct net_device *dev, struct ethtool_ts_info *info)
memset(info, 0, sizeof(*info));
info->cmd = ETHTOOL_GET_TS_INFO;

- if (phy_has_tsinfo(phydev))
- return phy_ts_info(phydev, info);
- if (ops->get_ts_info)
- return ops->get_ts_info(dev, info);
+ switch (dev->selected_timestamping_layer) {
+
+ case MAC_TIMESTAMPING:
+ if (ops->get_ts_info)
+ return ops->get_ts_info(dev, info);
+ break;
+
+ case PHY_TIMESTAMPING:
+ if (phy_has_tsinfo(phydev)) {
+ return phy_ts_info(phydev, info);
+ }
+ WARN_ON(1);
+ return -ENODEV;
+ }

info->so_timestamping = SOF_TIMESTAMPING_RX_SOFTWARE |
SOF_TIMESTAMPING_SOFTWARE;
--
2.20.1