[PATCHv4 net-next] bonding: add software tx timestamping support

[Hangbin Liu <liuhangbin@gmail.com>]

Currently, bonding only obtain the timestamp (ts) information of
the active slave, which is available only for modes 1, 5, and 6.
For other modes, bonding only has software rx timestamping support.

However, some users who use modes such as LACP also want tx timestamp
support. To address this issue, let's check the ts information of each
slave. If all slaves support tx timestamping, we can enable tx
timestamping support for the bond.

Suggested-by: Miroslav Lichvar <mlichvar@redhat.com>
Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
---
v4: add ASSERT_RTNL to make sure bond_ethtool_get_ts_info() called via
    RTNL. Only check _TX_SOFTWARE for the slaves.
v3: remove dev_hold/dev_put. remove the '\' for line continuation.
v2: check each slave's ts info to make sure bond support sw tx
    timestamping
---
 drivers/net/bonding/bond_main.c | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index 00646aa315c3..9cf49b61f4b3 100644
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -5686,11 +5686,17 @@ static int bond_ethtool_get_ts_info(struct net_device *bond_dev,
 				    struct ethtool_ts_info *info)
 {
 	struct bonding *bond = netdev_priv(bond_dev);
+	struct ethtool_ts_info ts_info;
 	const struct ethtool_ops *ops;
 	struct net_device *real_dev;
+	bool sw_tx_support = false;
 	struct phy_device *phydev;
+	struct list_head *iter;
+	struct slave *slave;
 	int ret = 0;
 
+	ASSERT_RTNL();
+
 	rcu_read_lock();
 	real_dev = bond_option_active_slave_get_rcu(bond);
 	dev_hold(real_dev);
@@ -5707,10 +5713,36 @@ static int bond_ethtool_get_ts_info(struct net_device *bond_dev,
 			ret = ops->get_ts_info(real_dev, info);
 			goto out;
 		}
+	} else {
+		/* Check if all slaves support software tx timestamping */
+		rcu_read_lock();
+		bond_for_each_slave_rcu(bond, slave, iter) {
+			ret = -1;
+			ops = slave->dev->ethtool_ops;
+			phydev = slave->dev->phydev;
+
+			if (phy_has_tsinfo(phydev))
+				ret = phy_ts_info(phydev, &ts_info);
+			else if (ops->get_ts_info)
+				ret = ops->get_ts_info(slave->dev, &ts_info);
+
+			if (!ret && (ts_info.so_timestamping & SOF_TIMESTAMPING_TX_SOFTWARE)) {
+				sw_tx_support = true;
+				continue;
+			}
+
+			sw_tx_support = false;
+			break;
+		}
+		rcu_read_unlock();
 	}
 
+	ret = 0;
 	info->so_timestamping = SOF_TIMESTAMPING_RX_SOFTWARE |
 				SOF_TIMESTAMPING_SOFTWARE;
+	if (sw_tx_support)
+		info->so_timestamping |= SOF_TIMESTAMPING_TX_SOFTWARE;
+
 	info->phc_index = -1;
 
 out:
-- 
2.38.1