Re: [PATCH v4 net-next 4/7] net: ethtool: let the core choose RSS context IDs

---
 include/linux/ethtool.h | 40 ++++++++++++++++++++++++---
 net/core/dev.c          | 15 ++++++++---
 net/ethtool/ioctl.c     | 60 ++++++++++++++++++++++++++++++-----------
 3 files changed, 93 insertions(+), 22 deletions(-)

diff --git a/include/linux/ethtool.h b/include/linux/ethtool.h
index 229a23571008..975fda7218f8 100644
--- a/include/linux/ethtool.h
+++ b/include/linux/ethtool.h

@@ -747,10 +747,33 @@ struct ethtool_mm_stats {
  * @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.
- * @set_rxfh_context: Create, remove and configure RSS contexts. Allows setting
+ * @create_rxfh_context: Create a new RSS context with the specified RX flow
+ *	hash indirection table, hash key, and hash function.
+ *	Arguments which are set to %NULL or zero will be populated to
+ *	appropriate defaults by the driver.
+ *	The &struct ethtool_rxfh_context for this context is passed in @ctx;
+ *	note that the indir table, hkey and hfunc are not yet populated as
+ *	of this call.  The driver does not need to update these; the core
+ *	will do so if this op succeeds.
+ *	If the driver provides this method, it must also provide
+ *	@modify_rxfh_context and @remove_rxfh_context.
+ *	Returns a negative error code or zero.
+ * @modify_rxfh_context: Reconfigure the specified RSS context.  Allows setting
  *	the contents of the RX flow hash indirection table, hash key, and/or
- *	hash function associated to the given context. Arguments which are set
- *	to %NULL or zero will remain unchanged.
+ *	hash function associated with the given context.
+ *	Arguments which are set to %NULL or zero will remain unchanged.
+ *	The &struct ethtool_rxfh_context for this context is passed in @ctx;
+ *	note that it will still contain the *old* settings.  The driver does
+ *	not need to update these; the core will do so if this op succeeds.
+ *	Returns a negative error code or zero. An error code must be returned
+ *	if at least one unsupported change was requested.
+ * @remove_rxfh_context: Remove the specified RSS context.
+ *	The &struct ethtool_rxfh_context for this context is passed in @ctx.
+ *	Returns a negative error code or zero.
+ * @set_rxfh_context: Deprecated API to create, remove and configure RSS
+ *	contexts. Allows setting the contents of the RX flow hash indirection
+ *	table, hash key, and/or hash function associated to the given context.
+ *	Arguments which are set to %NULL or zero will remain unchanged.
  *	Returns a negative error code or zero. An error code must be returned
  *	if at least one unsupported change was requested.
  * @get_channels: Get number of channels.

@@ -901,6 +924,17 @@ struct ethtool_ops {
 			    const u8 *key, const u8 hfunc);
 	int	(*get_rxfh_context)(struct net_device *, u32 *indir, u8 *key,
 				    u8 *hfunc, u32 rss_context);
+	int	(*create_rxfh_context)(struct net_device *,
+				       struct ethtool_rxfh_context *ctx,
+				       const u32 *indir, const u8 *key,
+				       const u8 hfunc, u32 rss_context);
+	int	(*modify_rxfh_context)(struct net_device *,
+				       struct ethtool_rxfh_context *ctx,
+				       const u32 *indir, const u8 *key,
+				       const u8 hfunc, u32 rss_context);
+	int	(*remove_rxfh_context)(struct net_device *,
+				       struct ethtool_rxfh_context *ctx,
+				       u32 rss_context);
 	int	(*set_rxfh_context)(struct net_device *, const u32 *indir,
 				    const u8 *key, const u8 hfunc,
 				    u32 *rss_context, bool delete);

diff --git a/net/core/dev.c b/net/core/dev.c
index 05e95abdfd17..637218adca22 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c

@@ -10882,16 +10882,23 @@ static void netdev_rss_contexts_free(struct net_device *dev)
 	struct ethtool_rxfh_context *ctx;
 	unsigned long context;
 
-	if (dev->ethtool_ops->set_rxfh_context)
+	if (dev->ethtool_ops->create_rxfh_context ||
+	    dev->ethtool_ops->set_rxfh_context)
 		xa_for_each(&dev->ethtool->rss_ctx, context, ctx) {
 			u32 *indir = ethtool_rxfh_context_indir(ctx);
 			u8 *key = ethtool_rxfh_context_key(ctx);
 			u32 concast = context;
 
 			xa_erase(&dev->ethtool->rss_ctx, context);
-			dev->ethtool_ops->set_rxfh_context(dev, indir, key,
-							   ctx->hfunc, &concast,
-							   true);
+			if (dev->ethtool_ops->create_rxfh_context)
+				dev->ethtool_ops->remove_rxfh_context(dev, ctx,
+								      context);

+			else
+				dev->ethtool_ops->set_rxfh_context(dev, indir,
+								   key,
+								   ctx->hfunc,
+								   &concast,
+								   true);
 			kfree(ctx);
 		}
 	xa_destroy(&dev->ethtool->rss_ctx);

diff --git a/net/ethtool/ioctl.c b/net/ethtool/ioctl.c
index 1d13bc8fbb75..c23d2bd3cd2a 100644
--- a/net/ethtool/ioctl.c
+++ b/net/ethtool/ioctl.c

@@ -1274,7 +1274,8 @@ static noinline_for_stack int ethtool_set_rxfh(struct net_device *dev,
 	if (rxfh.rsvd8[0] || rxfh.rsvd8[1] || rxfh.rsvd8[2] || rxfh.rsvd32)
 		return -EINVAL;
 	/* Most drivers don't handle rss_context, check it's 0 as well */
-	if (rxfh.rss_context && !ops->set_rxfh_context)
+	if (rxfh.rss_context && !(ops->create_rxfh_context ||
+				  ops->set_rxfh_context))
 		return -EOPNOTSUPP;
 	create = rxfh.rss_context == ETH_RXFH_CONTEXT_ALLOC;
 

@@ -1349,8 +1350,24 @@ static noinline_for_stack int ethtool_set_rxfh(struct net_device *dev,
 		}
 		ctx->indir_size = dev_indir_size;
 		ctx->key_size = dev_key_size;
-		ctx->hfunc = rxfh.hfunc;
 		ctx->priv_size = ops->rxfh_priv_size;
+		/* Initialise to an empty context */
+		ctx->indir_no_change = ctx->key_no_change = 1;
+		ctx->hfunc = ETH_RSS_HASH_NO_CHANGE;
+		if (ops->create_rxfh_context) {
+			u32 limit = dev->ethtool->rss_ctx_max_id ?: U32_MAX;
+			u32 ctx_id;
+
+			/* driver uses new API, core allocates ID */
+			ret = xa_alloc(&dev->ethtool->rss_ctx, &ctx_id, ctx,
+				       XA_LIMIT(1, limit), GFP_KERNEL_ACCOUNT);
+			if (ret < 0) {
+				kfree(ctx);
+				goto out;
+			}
+			WARN_ON(!ctx_id); /* can't happen */
+			rxfh.rss_context = ctx_id;
+		}
 	} else if (rxfh.rss_context) {
 		ctx = xa_load(&dev->ethtool->rss_ctx, rxfh.rss_context);
 		if (!ctx) {

@@ -1359,15 +1376,34 @@ static noinline_for_stack int ethtool_set_rxfh(struct net_device *dev,
 		}
 	}
 
-	if (rxfh.rss_context)
-		ret = ops->set_rxfh_context(dev, indir, hkey, rxfh.hfunc,
-					    &rxfh.rss_context, delete);
-	else
+	if (rxfh.rss_context) {
+		if (ops->create_rxfh_context) {
+			if (create)
+				ret = ops->create_rxfh_context(dev, ctx, indir,
+							       hkey, rxfh.hfunc,
+							       rxfh.rss_context);
+			else if (delete)
+				ret = ops->remove_rxfh_context(dev, ctx,
+							       rxfh.rss_context);
+			else
+				ret = ops->modify_rxfh_context(dev, ctx, indir,
+							       hkey, rxfh.hfunc,
+							       rxfh.rss_context);
+		} else {
+			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 (create)
+		if (create) {
 			/* failed to create, free our new tracking entry */
+			if (ops->create_rxfh_context)
+				xa_erase(&dev->ethtool->rss_ctx, rxfh.rss_context);
 			kfree(ctx);
+		}
 		goto out;
 	}
 

@@ -1383,12 +1419,8 @@ static noinline_for_stack int ethtool_set_rxfh(struct net_device *dev,
 			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 (create && !ops->create_rxfh_context) {
+		/* driver uses old API, it chose context ID */
 		if (WARN_ON(xa_load(&dev->ethtool->rss_ctx, rxfh.rss_context))) {
 			/* context ID reused, our tracking is screwed */
 			kfree(ctx);

@@ -1400,8 +1432,6 @@ static noinline_for_stack int ethtool_set_rxfh(struct net_device *dev,
 			kfree(ctx);
 			goto out;
 		}
-		ctx->indir_no_change = rxfh.indir_size == ETH_RXFH_INDIR_NO_CHANGE;
-		ctx->key_no_change = !rxfh.key_size;
 	}
 	if (delete) {
 		WARN_ON(xa_erase(&dev->ethtool->rss_ctx, rxfh.rss_context) != ctx);