[RFC PATCH v3 net-next 3/7] net: ethtool: record custom RSS contexts in the IDR

[<edward.cree@amd.com>]

From: Edward Cree <ecree.xilinx@gmail.com>

Since drivers are still choosing the context IDs, we have to force the
 IDR to use the ID they've chosen rather than picking one ourselves.

Signed-off-by: Edward Cree <ecree.xilinx@gmail.com>
---
 include/linux/ethtool.h | 14 ++++++++
 net/ethtool/ioctl.c     | 71 +++++++++++++++++++++++++++++++++++++++--
 2 files changed, 83 insertions(+), 2 deletions(-)

diff --git a/include/linux/ethtool.h b/include/linux/ethtool.h
index c770e32d79e6..f7317b53ab61 100644
--- a/include/linux/ethtool.h
+++ b/include/linux/ethtool.h
@@ -194,6 +194,17 @@ 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)
@@ -731,6 +742,8 @@ struct ethtool_mm_stats {
  *	will remain unchanged.
  *	Returns a negative error code or zero. An error code must be returned
  *	if at least one unsupported change was requested.
+ * @rxfh_priv_size: size of the driver private data area the core should
+ *	allocate for an RSS context.
  * @get_rxfh_context: Get the contents of the RX flow hash indirection table,
  *	hash key, and/or hash function assiciated to the given rss context.
  *	Returns a negative error code or zero.
@@ -824,6 +837,7 @@ struct ethtool_ops {
 	u32     cap_link_lanes_supported:1;
 	u32	supported_coalesce_params;
 	u32	supported_ring_params;
+	u16	rxfh_priv_size;
 	void	(*get_drvinfo)(struct net_device *, struct ethtool_drvinfo *);
 	int	(*get_regs_len)(struct net_device *);
 	void	(*get_regs)(struct net_device *, struct ethtool_regs *, void *);
diff --git a/net/ethtool/ioctl.c b/net/ethtool/ioctl.c
index de78b24fffc9..db596b61c6ab 100644
--- a/net/ethtool/ioctl.c
+++ b/net/ethtool/ioctl.c
@@ -1249,6 +1249,7 @@ static noinline_for_stack int ethtool_set_rxfh(struct net_device *dev,
 {
 	int ret;
 	const struct ethtool_ops *ops = dev->ethtool_ops;
+	struct ethtool_rxfh_context *ctx = NULL;
 	struct ethtool_rxnfc rx_rings;
 	struct ethtool_rxfh rxfh;
 	u32 dev_indir_size = 0, dev_key_size = 0, i;
@@ -1256,7 +1257,7 @@ static noinline_for_stack int ethtool_set_rxfh(struct net_device *dev,
 	u8 *hkey = NULL;
 	u8 *rss_config;
 	u32 rss_cfg_offset = offsetof(struct ethtool_rxfh, rss_config[0]);
-	bool delete = false;
+	bool create = false, delete = false;
 
 	if (!ops->get_rxnfc || !ops->set_rxfh)
 		return -EOPNOTSUPP;
@@ -1275,6 +1276,7 @@ static noinline_for_stack int ethtool_set_rxfh(struct net_device *dev,
 	/* Most drivers don't handle rss_context, check it's 0 as well */
 	if (rxfh.rss_context && !ops->set_rxfh_context)
 		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 or function.
@@ -1332,13 +1334,42 @@ static noinline_for_stack int ethtool_set_rxfh(struct net_device *dev,
 		}
 	}
 
+	if (create) {
+		if (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->priv_size = ops->rxfh_priv_size;
+	} else if (rxfh.rss_context) {
+		ctx = idr_find(&dev->ethtool->rss_ctx, rxfh.rss_context);
+		if (!ctx) {
+			ret = -ENOENT;
+			goto out;
+		}
+	}
+
 	if (rxfh.rss_context)
 		ret = ops->set_rxfh_context(dev, indir, hkey, rxfh.hfunc,
 					    &rxfh.rss_context, delete);
 	else
 		ret = ops->set_rxfh(dev, indir, hkey, rxfh.hfunc);
-	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.rss_context, sizeof(rxfh.rss_context)))
@@ -1351,6 +1382,42 @@ 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(idr_find(&dev->ethtool->rss_ctx, rxfh.rss_context))) {
+			/* context ID reused, our tracking is screwed */
+			kfree(ctx);
+			goto out;
+		}
+		/* Allocate the exact ID the driver gave us */
+		WARN_ON(idr_alloc(&dev->ethtool->rss_ctx, ctx, rxfh.rss_context,
+				  rxfh.rss_context + 1, GFP_KERNEL) !=
+			rxfh.rss_context);
+		ctx->indir_no_change = rxfh.indir_size == ETH_RXFH_INDIR_NO_CHANGE;
+		ctx->key_no_change = !rxfh.key_size;
+	}
+	if (delete) {
+		WARN_ON(idr_remove(&dev->ethtool->rss_ctx, rxfh.rss_context) != ctx);
+		kfree(ctx);
+	} else if (ctx) {
+		if (indir) {
+			for (i = 0; i < dev_indir_size; i++)
+				ethtool_rxfh_context_indir(ctx)[i] = indir[i];
+			ctx->indir_no_change = 0;
+		}
+		if (hkey) {
+			memcpy(ethtool_rxfh_context_key(ctx), hkey,
+			       dev_key_size);
+			ctx->key_no_change = 0;
+		}
+		if (rxfh.hfunc != ETH_RSS_HASH_NO_CHANGE)
+			ctx->hfunc = rxfh.hfunc;
+	}
 
 out:
 	kfree(rss_config);