[PATCH 4.14 02/25] net/ethtool/ioctl: return -EOPNOTSUPP if we have no phy stats

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

From: Daniil Tatianin <d-tatianin@yandex-team.ru>

[ 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>
---
 net/core/ethtool.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/core/ethtool.c b/net/core/ethtool.c
index 749d48393d06..fe2217e339dc 100644
--- a/net/core/ethtool.c
+++ b/net/core/ethtool.c
@@ -1969,7 +1969,8 @@ 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;
-- 
2.35.1