Merge branch 'net-define-new-hwtstamp-flag-and-return-it-to-userspace'

Hangbin Liu says:

====================
net: define new hwtstamp flag and return it to userspace

This patchset defined the new hwtstamp flag HWTSTAMP_FLAG_BONDED_PHC_INDEX
to make userspace program build pass with old kernel header by settting ifdef.

Let's also return the flag when do SIOC[G/S]HWTSTAMP to let userspace know
that it's necessary for a given netdev.
====================

Link: https://lore.kernel.org/r/20211229080938.231324-1-liuhangbin@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/bonding/bond_main.c

@@ -4124,28 +4124,38 @@ static int bond_eth_ioctl(struct net_device *bond_dev, struct ifreq *ifr, int cm
 
 		break;
 	case SIOCSHWTSTAMP:
-	case SIOCGHWTSTAMP:
 		if (copy_from_user(&cfg, ifr->ifr_data, sizeof(cfg)))
 			return -EFAULT;
 
-		if (cfg.flags & HWTSTAMP_FLAG_BONDED_PHC_INDEX) {
-			rcu_read_lock();
-			real_dev = bond_option_active_slave_get_rcu(bond);
-			rcu_read_unlock();
-			if (real_dev) {
-				strscpy_pad(ifrr.ifr_name, real_dev->name, IFNAMSIZ);
-				ifrr.ifr_ifru = ifr->ifr_ifru;
+		if (!(cfg.flags & HWTSTAMP_FLAG_BONDED_PHC_INDEX))
+			return -EOPNOTSUPP;
 
-				ops = real_dev->netdev_ops;
-				if (netif_device_present(real_dev) && ops->ndo_eth_ioctl) {
-					res = ops->ndo_eth_ioctl(real_dev, &ifrr, cmd);
+		fallthrough;
+	case SIOCGHWTSTAMP:
+		rcu_read_lock();
+		real_dev = bond_option_active_slave_get_rcu(bond);
+		rcu_read_unlock();
+		if (!real_dev)
+			return -EOPNOTSUPP;
 
-					if (!res)
-						ifr->ifr_ifru = ifrr.ifr_ifru;
+		strscpy_pad(ifrr.ifr_name, real_dev->name, IFNAMSIZ);
+		ifrr.ifr_ifru = ifr->ifr_ifru;
 
-					return res;
-				}
-			}
+		ops = real_dev->netdev_ops;
+		if (netif_device_present(real_dev) && ops->ndo_eth_ioctl) {
+			res = ops->ndo_eth_ioctl(real_dev, &ifrr, cmd);
+			if (res)
+				return res;
+
+			ifr->ifr_ifru = ifrr.ifr_ifru;
+			if (copy_from_user(&cfg, ifr->ifr_data, sizeof(cfg)))
+				return -EFAULT;
+
+			/* Set the BOND_PHC_INDEX flag to notify user space */
+			cfg.flags |= HWTSTAMP_FLAG_BONDED_PHC_INDEX;
+
+			return copy_to_user(ifr->ifr_data, &cfg, sizeof(cfg)) ?
+				-EFAULT : 0;
 		}
 		fallthrough;
 	default:

include/uapi/linux/net_tstamp.h

@@ -87,6 +87,7 @@ enum hwtstamp_flags {
 	 * will be the PHC index.
 	 */
 	HWTSTAMP_FLAG_BONDED_PHC_INDEX = (1<<0),
+#define HWTSTAMP_FLAG_BONDED_PHC_INDEX	HWTSTAMP_FLAG_BONDED_PHC_INDEX
 
 	HWTSTAMP_FLAG_LAST = HWTSTAMP_FLAG_BONDED_PHC_INDEX,
 	HWTSTAMP_FLAG_MASK = (HWTSTAMP_FLAG_LAST - 1) | HWTSTAMP_FLAG_LAST