[PATCH net-next 2/3] net: ethtool: move checks before rtnl_lock() in ethnl_set_rings

From: Guangbin Huang
Date: Fri Apr 08 2022 - 03:18:36 EST


From: Jie Wang <wangjie125@xxxxxxxxxx>

Currently these two checks in ethnl_set_rings are added after rtnl_lock()
which will do useless works if the request is invalid.

So this patch moves these checks before the rtnl_lock() to avoid these
costs.

Signed-off-by: Jie Wang <wangjie125@xxxxxxxxxx>
Signed-off-by: Guangbin Huang <huangguangbin2@xxxxxxxxxx>
---
net/ethtool/rings.c | 38 ++++++++++++++++++++------------------
1 file changed, 20 insertions(+), 18 deletions(-)

diff --git a/net/ethtool/rings.c b/net/ethtool/rings.c
index 9ed60c507d97..46415d8fc256 100644
--- a/net/ethtool/rings.c
+++ b/net/ethtool/rings.c
@@ -152,6 +152,26 @@ int ethnl_set_rings(struct sk_buff *skb, struct genl_info *info)
if (!ops->get_ringparam || !ops->set_ringparam)
goto out_dev;

+ if (tb[ETHTOOL_A_RINGS_RX_BUF_LEN] &&
+ nla_get_u32(tb[ETHTOOL_A_RINGS_RX_BUF_LEN]) != 0 &&
+ !(ops->supported_ring_params & ETHTOOL_RING_USE_RX_BUF_LEN)) {
+ ret = -EOPNOTSUPP;
+ NL_SET_ERR_MSG_ATTR(info->extack,
+ tb[ETHTOOL_A_RINGS_RX_BUF_LEN],
+ "setting rx buf len not supported");
+ goto out_dev;
+ }
+
+ if (tb[ETHTOOL_A_RINGS_CQE_SIZE] &&
+ nla_get_u32(tb[ETHTOOL_A_RINGS_CQE_SIZE]) &&
+ !(ops->supported_ring_params & ETHTOOL_RING_USE_CQE_SIZE)) {
+ ret = -EOPNOTSUPP;
+ NL_SET_ERR_MSG_ATTR(info->extack,
+ tb[ETHTOOL_A_RINGS_CQE_SIZE],
+ "setting cqe size not supported");
+ goto out_dev;
+ }
+
if (tb[ETHTOOL_A_RINGS_TX_PUSH] &&
!(ops->supported_ring_params & ETHTOOL_RING_USE_TX_PUSH)) {
ret = -EOPNOTSUPP;
@@ -201,24 +221,6 @@ int ethnl_set_rings(struct sk_buff *skb, struct genl_info *info)
goto out_ops;
}

- if (kernel_ringparam.rx_buf_len != 0 &&
- !(ops->supported_ring_params & ETHTOOL_RING_USE_RX_BUF_LEN)) {
- ret = -EOPNOTSUPP;
- NL_SET_ERR_MSG_ATTR(info->extack,
- tb[ETHTOOL_A_RINGS_RX_BUF_LEN],
- "setting rx buf len not supported");
- goto out_ops;
- }
-
- if (kernel_ringparam.cqe_size &&
- !(ops->supported_ring_params & ETHTOOL_RING_USE_CQE_SIZE)) {
- ret = -EOPNOTSUPP;
- NL_SET_ERR_MSG_ATTR(info->extack,
- tb[ETHTOOL_A_RINGS_CQE_SIZE],
- "setting cqe size not supported");
- goto out_ops;
- }
-
ret = dev->ethtool_ops->set_ringparam(dev, &ringparam,
&kernel_ringparam, info->extack);
if (ret < 0)
--
2.33.0