[PATCH net-next 12/14] net: ethtool: ioctl: concentrate the locking

[Jakub Kicinski <kuba@kernel.org>]

Add another layer of helper functions to make upcoming locking
changes easier. Otherwise we'd need a pretty complex goto
structure. netdev instance lock is now taken slightly sooner
but that should not be an issue since rtnl_lock is already held,
anyway.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---
 net/ethtool/ioctl.c | 35 +++++++++++++++++++++++++----------
 1 file changed, 25 insertions(+), 10 deletions(-)

diff --git a/net/ethtool/ioctl.c b/net/ethtool/ioctl.c
index 1d74ee67e77a..6c3a7e8644ae 100644
--- a/net/ethtool/ioctl.c
+++ b/net/ethtool/ioctl.c
@@ -3257,18 +3257,14 @@ static int ethtool_set_fecparam(struct net_device *dev, void __user *useraddr)
 /* The main entry point in this file.  Called from net/core/dev_ioctl.c */
 
 static int
-__dev_ethtool(struct net *net, struct ifreq *ifr, void __user *useraddr,
-	      u32 ethcmd, struct ethtool_devlink_compat *devlink_state)
+dev_ethtool_locked(struct net *net, struct net_device *dev,
+		   void __user *useraddr,
+		   u32 ethcmd, struct ethtool_devlink_compat *devlink_state)
 {
-	struct net_device *dev;
 	u32 sub_cmd;
 	int rc;
 	netdev_features_t old_features;
 
-	dev = __dev_get_by_name(net, ifr->ifr_name);
-	if (!dev)
-		return -ENODEV;
-
 	if (ethcmd == ETHTOOL_PERQUEUE) {
 		if (copy_from_user(&sub_cmd, useraddr + sizeof(ethcmd), sizeof(sub_cmd)))
 			return -EFAULT;
@@ -3319,7 +3315,6 @@ __dev_ethtool(struct net *net, struct ifreq *ifr, void __user *useraddr,
 			return -EPERM;
 	}
 
-	netdev_lock_ops(dev);
 	if (dev->dev.parent)
 		pm_runtime_get_sync(dev->dev.parent);
 
@@ -3559,7 +3554,29 @@ __dev_ethtool(struct net *net, struct ifreq *ifr, void __user *useraddr,
 out:
 	if (dev->dev.parent)
 		pm_runtime_put(dev->dev.parent);
+
+	return rc;
+}
+
+static int
+__dev_ethtool(struct net *net, struct ifreq *ifr, void __user *useraddr,
+	      u32 ethcmd, struct ethtool_devlink_compat *devlink_state)
+{
+	struct net_device *dev;
+	int rc;
+
+	rtnl_lock();
+	dev = __dev_get_by_name(net, ifr->ifr_name);
+	if (!dev) {
+		rc = -ENODEV;
+		goto exit_rtnl_unlock;
+	}
+
+	netdev_lock_ops(dev);
+	rc = dev_ethtool_locked(net, dev, useraddr, ethcmd, devlink_state);
 	netdev_unlock_ops(dev);
+exit_rtnl_unlock:
+	rtnl_unlock();
 
 	return rc;
 }
@@ -3587,9 +3604,7 @@ int dev_ethtool(struct net *net, struct ifreq *ifr, void __user *useraddr)
 		break;
 	}
 
-	rtnl_lock();
 	rc = __dev_ethtool(net, ifr, useraddr, ethcmd, state);
-	rtnl_unlock();
 	if (rc)
 		goto exit_free;
 
-- 
2.54.0