net/ethtool/ioctl: return -EOPNOTSUPP if we have no phy stats

[ Upstream commit 9deb1e9fb88b1120a908676fa33bdf9e2eeaefce ]

It's not very useful to copy back an empty ethtool_stats struct and
return 0 if we didn't actually have any stats. This also allows for
further simplification of this function in the future commits.

Signed-off-by: Daniil Tatianin <d-tatianin@yandex-team.ru>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/net/core/ethtool.c b/net/core/ethtool.c
index cbd1885f2459211991ef1ea966d8599fddce9d78..9ae38c3e2bf0aaf1e921579d171112fa186a58b4 100644 (file)
--- a/net/core/ethtool.c
+++ b/net/core/ethtool.c
@@ -1947,7 +1947,8 @@ static int ethtool_get_phy_stats(struct net_device *dev, void __user *useraddr)
                return n_stats;
        if (n_stats > S32_MAX / sizeof(u64))
                return -ENOMEM;
-       WARN_ON_ONCE(!n_stats);
+       if (WARN_ON_ONCE(!n_stats))
+               return -EOPNOTSUPP;
 
        if (copy_from_user(&stats, useraddr, sizeof(stats)))
                return -EFAULT;