Re: [PATCH v6 net-next 3/9] net: ethtool: record custom RSS contexts in the XArray

Signed-off-by: Edward Cree <ecree.xilinx@gmail.com>
---
  include/linux/ethtool.h | 14 ++++++++
  net/ethtool/ioctl.c     | 74 ++++++++++++++++++++++++++++++++++++++++-
  2 files changed, 87 insertions(+), 1 deletion(-)

diff --git a/include/linux/ethtool.h b/include/linux/ethtool.h
index 13c9c819de58..283ba4aff623 100644
--- a/include/linux/ethtool.h
+++ b/include/linux/ethtool.h

@@ -199,6 +199,17 @@ static inline u8 *ethtool_rxfh_context_key(struct ethtool_rxfh_context *ctx)
  	return (u8 *)(ethtool_rxfh_context_indir(ctx) + ctx->indir_size);
  }
  
+static inline size_t ethtool_rxfh_context_size(u32 indir_size, u32 key_size,
+					       u16 priv_size)
+{
+	size_t indir_bytes = array_size(indir_size, sizeof(u32));
+	size_t flex_len;
+
+	flex_len = size_add(size_add(indir_bytes, key_size),
+			    ALIGN(priv_size, sizeof(u32)));
+	return struct_size((struct ethtool_rxfh_context *)0, data, flex_len);

+}
+
  /* declare a link mode bitmap */
  #define __ETHTOOL_DECLARE_LINK_MODE_MASK(name)		\
  	DECLARE_BITMAP(name, __ETHTOOL_LINK_MODE_MASK_NBITS)

@@ -709,6 +720,8 @@ struct ethtool_rxfh_param {
   *	contexts.
   * @cap_rss_sym_xor_supported: indicates if the driver supports symmetric-xor
   *	RSS.
+ * @rxfh_priv_size: size of the driver private data area the core should
+ *	allocate for an RSS context (in &struct ethtool_rxfh_context).
   * @supported_coalesce_params: supported types of interrupt coalescing.
   * @supported_ring_params: supported ring params.
   * @get_drvinfo: Report driver/device information. Modern drivers no

@@ -892,6 +905,7 @@ struct ethtool_ops {
  	u32     cap_link_lanes_supported:1;
  	u32     cap_rss_ctx_supported:1;
  	u32	cap_rss_sym_xor_supported:1;
+	u16	rxfh_priv_size;
  	u32	supported_coalesce_params;
  	u32	supported_ring_params;
  	void	(*get_drvinfo)(struct net_device *, struct ethtool_drvinfo *);

diff --git a/net/ethtool/ioctl.c b/net/ethtool/ioctl.c
index 998571f05deb..f879deb6ac4e 100644
--- a/net/ethtool/ioctl.c
+++ b/net/ethtool/ioctl.c

@@ -1278,10 +1278,12 @@ static noinline_for_stack int ethtool_set_rxfh(struct net_device *dev,
  	const struct ethtool_ops *ops = dev->ethtool_ops;
  	u32 dev_indir_size = 0, dev_key_size = 0, i;
  	struct ethtool_rxfh_param rxfh_dev = {};
+	struct ethtool_rxfh_context *ctx = NULL;
  	struct netlink_ext_ack *extack = NULL;
  	struct ethtool_rxnfc rx_rings;
  	struct ethtool_rxfh rxfh;
  	u32 indir_bytes = 0;
+	bool create = false;
  	u8 *rss_config;
  	int ret;
  

@@ -1309,6 +1311,7 @@ static noinline_for_stack int ethtool_set_rxfh(struct net_device *dev,
  	if ((rxfh.input_xfrm & RXH_XFRM_SYM_XOR) &&
  	    !ops->cap_rss_sym_xor_supported)
  		return -EOPNOTSUPP;
+	create = rxfh.rss_context == ETH_RXFH_CONTEXT_ALLOC;
  
  	/* If either indir, hash key or function is valid, proceed further.
  	 * Must request at least one change: indir size, hash key, function

@@ -1374,13 +1377,42 @@ static noinline_for_stack int ethtool_set_rxfh(struct net_device *dev,
  		}
  	}
  
+	if (create) {
+		if (rxfh_dev.rss_delete) {
+			ret = -EINVAL;
+			goto out;
+		}
+		ctx = kzalloc(ethtool_rxfh_context_size(dev_indir_size,
+							dev_key_size,
+							ops->rxfh_priv_size),
+			      GFP_KERNEL_ACCOUNT);
+		if (!ctx) {
+			ret = -ENOMEM;
+			goto out;
+		}
+		ctx->indir_size = dev_indir_size;
+		ctx->key_size = dev_key_size;
+		ctx->hfunc = rxfh.hfunc;
+		ctx->input_xfrm = rxfh.input_xfrm;
+		ctx->priv_size = ops->rxfh_priv_size;
+	} else if (rxfh.rss_context) {
+		ctx = xa_load(&dev->ethtool->rss_ctx, rxfh.rss_context);
+		if (!ctx) {
+			ret = -ENOENT;
+			goto out;
+		}
+	}
  	rxfh_dev.hfunc = rxfh.hfunc;
  	rxfh_dev.rss_context = rxfh.rss_context;
  	rxfh_dev.input_xfrm = rxfh.input_xfrm;
  
  	ret = ops->set_rxfh(dev, &rxfh_dev, extack);
-	if (ret)
+	if (ret) {
+		if (create)
+			/* failed to create, free our new tracking entry */
+			kfree(ctx);
  		goto out;
+	}
  
  	if (copy_to_user(useraddr + offsetof(struct ethtool_rxfh, rss_context),
  			 &rxfh_dev.rss_context, sizeof(rxfh_dev.rss_context)))

@@ -1393,6 +1425,46 @@ static noinline_for_stack int ethtool_set_rxfh(struct net_device *dev,
  		else if (rxfh.indir_size != ETH_RXFH_INDIR_NO_CHANGE)
  			dev->priv_flags |= IFF_RXFH_CONFIGURED;
  	}
+	/* Update rss_ctx tracking */
+	if (create) {
+		/* Ideally this should happen before calling the driver,
+		 * so that we can fail more cleanly; but we don't have the
+		 * context ID until the driver picks it, so we have to
+		 * wait until after.
+		 */
+		if (WARN_ON(xa_load(&dev->ethtool->rss_ctx, rxfh.rss_context))) {
+			/* context ID reused, our tracking is screwed */