[PATCH v2 net-next] ethtool: ioctl: improve error checking for set_wol

[Justin Chen]

The netlink version of set_wol checks for not supported wolopts and avoids
setting wol when the correct wolopt is already set. If we do the same with
the ioctl version then we can remove these checks from the driver layer.

Reviewed-by: Simon Horman <simon.horman@xxxxxxxxxxxx>
Signed-off-by: Justin Chen <justin.chen@xxxxxxxxxxxx>
---
v2
	- Return -EINVAL instead of -EOPNOTSUPP

 net/ethtool/ioctl.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/net/ethtool/ioctl.c b/net/ethtool/ioctl.c
index 6bb778e10461..37b582225854 100644
--- a/net/ethtool/ioctl.c
+++ b/net/ethtool/ioctl.c
@@ -1436,15 +1436,25 @@ static int ethtool_get_wol(struct net_device *dev, char __user *useraddr)
 
 static int ethtool_set_wol(struct net_device *dev, char __user *useraddr)
 {
-	struct ethtool_wolinfo wol;
+	struct ethtool_wolinfo wol, cur_wol;
 	int ret;
 
-	if (!dev->ethtool_ops->set_wol)
+	if (!dev->ethtool_ops->get_wol || !dev->ethtool_ops->set_wol)
 		return -EOPNOTSUPP;
 
+	memset(&cur_wol, 0, sizeof(struct ethtool_wolinfo));
+	cur_wol.cmd = ETHTOOL_GWOL;
+	dev->ethtool_ops->get_wol(dev, &cur_wol);
+
 	if (copy_from_user(&wol, useraddr, sizeof(wol)))
 		return -EFAULT;
 
+	if (wol.wolopts & ~cur_wol.supported)
+		return -EINVAL;
+
+	if (wol.wolopts == cur_wol.wolopts)
+		return 0;
+
 	ret = dev->ethtool_ops->set_wol(dev, &wol);
 	if (ret)
 		return ret;
-- 
2.7.4

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