[PATCH net-next v3 5/6] devlink: hold a reference to the netdevice around ethtool compat

[Jakub Kicinski <jakub.kicinski@netronome.com>]

When ethtool is calling into devlink compat code make sure we have
a reference on the netdevice on which the operation was invoked.

v3: move the hold/lock logic into devlink_compat_* functions (Florian)

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
---
 net/core/devlink.c | 34 +++++++++++++++++++++++-----------
 net/core/ethtool.c | 13 ++-----------
 2 files changed, 25 insertions(+), 22 deletions(-)

diff --git a/net/core/devlink.c b/net/core/devlink.c
index a13055160be0..78c6ea1870ca 100644
--- a/net/core/devlink.c
+++ b/net/core/devlink.c
@@ -6430,27 +6430,39 @@ void devlink_compat_running_version(struct net_device *dev,
 {
 	struct devlink *devlink;
 
+	dev_hold(dev);
+	rtnl_unlock();
+
 	devlink = netdev_to_devlink(dev);
-	if (!devlink || !devlink->ops || !devlink->ops->info_get)
-		return;
+	if (devlink && devlink->ops && devlink->ops->info_get) {
+		mutex_lock(&devlink->lock);
+		__devlink_compat_running_version(devlink, buf, len);
+		mutex_unlock(&devlink->lock);
+	}
 
-	mutex_lock(&devlink->lock);
-	__devlink_compat_running_version(devlink, buf, len);
-	mutex_unlock(&devlink->lock);
+	rtnl_lock();
+	dev_put(dev);
 }
 
 int devlink_compat_flash_update(struct net_device *dev, const char *file_name)
 {
 	struct devlink *devlink;
-	int ret;
+	int ret = -EOPNOTSUPP;
+
+	dev_hold(dev);
+	rtnl_unlock();
 
 	devlink = netdev_to_devlink(dev);
-	if (!devlink || !devlink->ops || !devlink->ops->flash_update)
-		return -EOPNOTSUPP;
+	if (devlink && devlink->ops && devlink->ops->flash_update) {
+		mutex_lock(&devlink->lock);
+		ret = devlink->ops->flash_update(devlink, file_name,
+						 NULL, NULL);
+		mutex_unlock(&devlink->lock);
+	}
+
+	rtnl_lock();
+	dev_put(dev);
 
-	mutex_lock(&devlink->lock);
-	ret = devlink->ops->flash_update(devlink, file_name, NULL, NULL);
-	mutex_unlock(&devlink->lock);
 	return ret;
 }
 
diff --git a/net/core/ethtool.c b/net/core/ethtool.c
index 1320e8dce559..47558ffae423 100644
--- a/net/core/ethtool.c
+++ b/net/core/ethtool.c
@@ -805,11 +805,9 @@ static noinline_for_stack int ethtool_get_drvinfo(struct net_device *dev,
 	if (ops->get_eeprom_len)
 		info.eedump_len = ops->get_eeprom_len(dev);
 
-	rtnl_unlock();
 	if (!info.fw_version[0])
 		devlink_compat_running_version(dev, info.fw_version,
 					       sizeof(info.fw_version));
-	rtnl_lock();
 
 	if (copy_to_user(useraddr, &info, sizeof(info)))
 		return -EFAULT;
@@ -2040,15 +2038,8 @@ static noinline_for_stack int ethtool_flash_device(struct net_device *dev,
 		return -EFAULT;
 	efl.data[ETHTOOL_FLASH_MAX_FILENAME - 1] = 0;
 
-	if (!dev->ethtool_ops->flash_device) {
-		int ret;
-
-		rtnl_unlock();
-		ret = devlink_compat_flash_update(dev, efl.data);
-		rtnl_lock();
-
-		return ret;
-	}
+	if (!dev->ethtool_ops->flash_device)
+		return devlink_compat_flash_update(dev, efl.data);
 
 	return dev->ethtool_ops->flash_device(dev, &efl);
 }
-- 
2.19.2