Merge branch 'ethtool-use-the-rss-context-xarray-in-ring-deactivation-safety-check'

Jakub Kicinski says:

====================
ethtool: use the rss context XArray in ring deactivation safety-check

Now that we have an XArray storing information about all extra
RSS contexts - use it to extend checks already performed using
ethtool_get_max_rxfh_channel().
====================

Link: https://patch.msgid.link/20240710174043.754664-1-kuba@kernel.orgSigned-off-by: Jakub Kicinski <kuba@kernel.org>

net/ethtool/channels.c

@@ -171,11 +171,9 @@ ethnl_set_channels(struct ethnl_req_info *req_info, struct genl_info *info)
 	 */
 	if (ethtool_get_max_rxnfc_channel(dev, &max_rxnfc_in_use))
 		max_rxnfc_in_use = 0;
-	if (!netif_is_rxfh_configured(dev) ||
-	    ethtool_get_max_rxfh_channel(dev, &max_rxfh_in_use))
-		max_rxfh_in_use = 0;
+	max_rxfh_in_use = ethtool_get_max_rxfh_channel(dev);
 	if (channels.combined_count + channels.rx_count <= max_rxfh_in_use) {
-		GENL_SET_ERR_MSG(info, "requested channel counts are too low for existing indirection table settings");
+		GENL_SET_ERR_MSG_FMT(info, "requested channel counts are too low for existing indirection table (%d)", max_rxfh_in_use);
 		return -EINVAL;
 	}
 	if (channels.combined_count + channels.rx_count <= max_rxnfc_in_use) {

net/ethtool/common.c

@@ -587,35 +587,64 @@ int ethtool_get_max_rxnfc_channel(struct net_device *dev, u64 *max)
 	return err;
 }
 
-int ethtool_get_max_rxfh_channel(struct net_device *dev, u32 *max)
+static u32 ethtool_get_max_rss_ctx_channel(struct net_device *dev)
+{
+	struct ethtool_rxfh_context *ctx;
+	unsigned long context;
+	u32 max_ring = 0;
+
+	mutex_lock(&dev->ethtool->rss_lock);
+	xa_for_each(&dev->ethtool->rss_ctx, context, ctx) {
+		u32 i, *tbl;
+
+		tbl = ethtool_rxfh_context_indir(ctx);
+		for (i = 0; i < ctx->indir_size; i++)
+			max_ring = max(max_ring, tbl[i]);
+	}
+	mutex_unlock(&dev->ethtool->rss_lock);
+
+	return max_ring;
+}
+
+u32 ethtool_get_max_rxfh_channel(struct net_device *dev)
 {
 	struct ethtool_rxfh_param rxfh = {};
-	u32 dev_size, current_max = 0;
+	u32 dev_size, current_max;
 	int ret;
 
+	/* While we do track whether RSS context has an indirection
+	 * table explicitly set by the user, no driver looks at that bit.
+	 * Assume drivers won't auto-regenerate the additional tables,
+	 * to be safe.
+	 */
+	current_max = ethtool_get_max_rss_ctx_channel(dev);
+
+	if (!netif_is_rxfh_configured(dev))
+		return current_max;
+
 	if (!dev->ethtool_ops->get_rxfh_indir_size ||
 	    !dev->ethtool_ops->get_rxfh)
-		return -EOPNOTSUPP;
+		return current_max;
 	dev_size = dev->ethtool_ops->get_rxfh_indir_size(dev);
 	if (dev_size == 0)
-		return -EOPNOTSUPP;
+		return current_max;
 
 	rxfh.indir = kcalloc(dev_size, sizeof(rxfh.indir[0]), GFP_USER);
 	if (!rxfh.indir)
-		return -ENOMEM;
+		return U32_MAX;
 
 	ret = dev->ethtool_ops->get_rxfh(dev, &rxfh);
-	if (ret)
-		goto out;
+	if (ret) {
+		current_max = U32_MAX;
+		goto out_free;
+	}
 
 	while (dev_size--)
 		current_max = max(current_max, rxfh.indir[dev_size]);
 
-	*max = current_max;
-
-out:
+out_free:
 	kfree(rxfh.indir);
-	return ret;
+	return current_max;
 }
 
 int ethtool_check_ops(const struct ethtool_ops *ops)

net/ethtool/common.h

@@ -42,7 +42,7 @@ int __ethtool_get_link(struct net_device *dev);
 bool convert_legacy_settings_to_link_ksettings(
 	struct ethtool_link_ksettings *link_ksettings,
 	const struct ethtool_cmd *legacy_settings);
-int ethtool_get_max_rxfh_channel(struct net_device *dev, u32 *max);
+u32 ethtool_get_max_rxfh_channel(struct net_device *dev);
 int ethtool_get_max_rxnfc_channel(struct net_device *dev, u64 *max);
 int __ethtool_get_ts_info(struct net_device *dev, struct ethtool_ts_info *info);
 

net/ethtool/ioctl.c

@@ -2049,9 +2049,7 @@ static noinline_for_stack int ethtool_set_channels(struct net_device *dev,
 	 * indirection table/rxnfc settings */
 	if (ethtool_get_max_rxnfc_channel(dev, &max_rxnfc_in_use))
 		max_rxnfc_in_use = 0;
-	if (!netif_is_rxfh_configured(dev) ||
-	    ethtool_get_max_rxfh_channel(dev, &max_rxfh_in_use))
-		max_rxfh_in_use = 0;
+	max_rxfh_in_use = ethtool_get_max_rxfh_channel(dev);
 	if (channels.combined_count + channels.rx_count <=
 	    max_t(u64, max_rxnfc_in_use, max_rxfh_in_use))
 		return -EINVAL;