netdev - [PATCH net-next 2/3] net: ethtool: move rxfh_fields callbacks under the rss

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Message-ID: <20250626202848.104457-3-kuba@kernel.org>
Date: Thu, 26 Jun 2025 13:28:47 -0700
From: Jakub Kicinski <kuba@...nel.org>
To: davem@...emloft.net
Cc: netdev@...r.kernel.org,
	edumazet@...gle.com,
	pabeni@...hat.com,
	andrew+netdev@...n.ch,
	horms@...nel.org,
	ecree.xilinx@...il.com,
	Jakub Kicinski <kuba@...nel.org>
Subject: [PATCH net-next 2/3] net: ethtool: move rxfh_fields callbacks under the rss_lock

Netlink code will want to perform the RSS_SET operation atomically
under the rss_lock. sfc wants to hold the rss_lock in rxfh_fields_get,
which makes that difficult. Lets move the locking up to the core
so that for all driver-facing callbacks rss_lock is taken consistently
by the core.

Signed-off-by: Jakub Kicinski <kuba@...nel.org>
---
 drivers/net/ethernet/sfc/ethtool_common.c |  9 ++-------
 net/ethtool/ioctl.c                       | 15 ++++++++++-----
 2 files changed, 12 insertions(+), 12 deletions(-)

diff --git a/drivers/net/ethernet/sfc/ethtool_common.c b/drivers/net/ethernet/sfc/ethtool_common.c
index 823263969f92..fa303e171d98 100644
--- a/drivers/net/ethernet/sfc/ethtool_common.c
+++ b/drivers/net/ethernet/sfc/ethtool_common.c
@@ -810,13 +810,10 @@ int efx_ethtool_get_rxfh_fields(struct net_device *net_dev,
 
 	ctx = &efx->rss_context.priv;
 
-	mutex_lock(&net_dev->ethtool->rss_lock);
 	if (info->rss_context) {
 		ctx = efx_find_rss_context_entry(efx, info->rss_context);
-		if (!ctx) {
-			rc = -ENOENT;
-			goto out_unlock;
-		}
+		if (!ctx)
+			return -ENOENT;
 	}
 
 	data = 0;
@@ -850,8 +847,6 @@ int efx_ethtool_get_rxfh_fields(struct net_device *net_dev,
 	}
 out_setdata_unlock:
 	info->data = data;
-out_unlock:
-	mutex_unlock(&net_dev->ethtool->rss_lock);
 	return rc;
 }
 
diff --git a/net/ethtool/ioctl.c b/net/ethtool/ioctl.c
index ce7d720b3c79..df376628ba19 100644
--- a/net/ethtool/ioctl.c
+++ b/net/ethtool/ioctl.c
@@ -1096,7 +1096,10 @@ ethtool_set_rxfh_fields(struct net_device *dev, u32 cmd, void __user *useraddr)
 	if (info.flow_type & FLOW_RSS)
 		fields.rss_context = info.rss_context;
 
-	return ops->set_rxfh_fields(dev, &fields, NULL);
+	mutex_lock(&dev->ethtool->rss_lock);
+	rc = ops->set_rxfh_fields(dev, &fields, NULL);
+	mutex_unlock(&dev->ethtool->rss_lock);
+	return rc;
 }
 
 static noinline_for_stack int
@@ -1123,7 +1126,9 @@ ethtool_get_rxfh_fields(struct net_device *dev, u32 cmd, void __user *useraddr)
 	if (info.flow_type & FLOW_RSS)
 		fields.rss_context = info.rss_context;
 
+	mutex_lock(&dev->ethtool->rss_lock);
 	ret = ops->get_rxfh_fields(dev, &fields);
+	mutex_unlock(&dev->ethtool->rss_lock);
 	if (ret < 0)
 		return ret;
 
@@ -1553,10 +1558,6 @@ static noinline_for_stack int ethtool_set_rxfh(struct net_device *dev,
 	     rxfh.input_xfrm == RXH_XFRM_NO_CHANGE))
 		return -EINVAL;
 
-	ret = ethtool_check_flow_types(dev, rxfh.input_xfrm);
-	if (ret)
-		return ret;
-
 	indir_bytes = dev_indir_size * sizeof(rxfh_dev.indir[0]);
 
 	/* Check settings which may be global rather than per RSS-context */
@@ -1617,6 +1618,10 @@ static noinline_for_stack int ethtool_set_rxfh(struct net_device *dev,
 
 	mutex_lock(&dev->ethtool->rss_lock);
 
+	ret = ethtool_check_flow_types(dev, rxfh.input_xfrm);
+	if (ret)
+		goto out_unlock;
+
 	if (rxfh.rss_context && rxfh_dev.rss_delete) {
 		ret = ethtool_check_rss_ctx_busy(dev, rxfh.rss_context);
 		if (ret)
-- 
2.50.0