net/hsr: Better frame dispatch

This patch removes the separate paths for frames coming from the outside, and
frames sent from the HSR device, and instead makes all frames go through
hsr_forward_skb() in hsr_forward.c. This greatly improves code readability and
also opens up the possibility for future support of the HSR Interlink device
that is the basis for HSR RedBoxes and HSR QuadBoxes, as well as VLAN
compatibility.

Other improvements:
* A reduction in the number of times an skb is copied on machines without
  HAVE_EFFICIENT_UNALIGNED_ACCESS, which improves throughput somewhat.
* Headers are now created using the standard eth_header(), and using the
  standard hard_header_len.
* Each HSR slave now gets its own private skb, so slave-specific fields can be
  correctly set.

Signed-off-by: Arvid Brodin <arvid.brodin@alten.se>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 161 insertions, 157 deletions

diff --git a/net/hsr/hsr_framereg.c b/net/hsr/hsr_framereg.c
index c9b78c52c75b..c709c13842cb 100644
--- a/net/hsr/hsr_framereg.c
+++ b/net/hsr/hsr_framereg.c
@@ -35,58 +35,56 @@ struct hsr_node {
 	struct rcu_head		rcu_head;
 };
 
-/*	TODO: use hash lists for mac addresses (linux/jhash.h)?    */
 
+/*	TODO: use hash lists for mac addresses (linux/jhash.h)?    */
 
 
-/* Search for mac entry. Caller must hold rcu read lock.
+/* seq_nr_after(a, b) - return true if a is after (higher in sequence than) b,
+ * false otherwise.
  */
-static struct hsr_node *find_node_by_AddrA(struct list_head *node_db,
-					   const unsigned char addr[ETH_ALEN])
+static bool seq_nr_after(u16 a, u16 b)
 {
-	struct hsr_node *node;
-
-	list_for_each_entry_rcu(node, node_db, mac_list) {
-		if (ether_addr_equal(node->MacAddressA, addr))
-			return node;
-	}
+	/* Remove inconsistency where
+	 * seq_nr_after(a, b) == seq_nr_before(a, b)
+	 */
+	if ((int) b - a == 32768)
+		return false;
 
-	return NULL;
+	return (((s16) (b - a)) < 0);
 }
+#define seq_nr_before(a, b)		seq_nr_after((b), (a))
+#define seq_nr_after_or_eq(a, b)	(!seq_nr_before((a), (b)))
+#define seq_nr_before_or_eq(a, b)	(!seq_nr_after((a), (b)))
 
 
-/* Search for mac entry. Caller must hold rcu read lock.
- */
-static struct hsr_node *find_node_by_AddrB(struct list_head *node_db,
-					   const unsigned char addr[ETH_ALEN])
+bool hsr_addr_is_self(struct hsr_priv *hsr, unsigned char *addr)
 {
 	struct hsr_node *node;
 
-	list_for_each_entry_rcu(node, node_db, mac_list) {
-		if (ether_addr_equal(node->MacAddressB, addr))
-			return node;
+	node = list_first_or_null_rcu(&hsr->self_node_db, struct hsr_node,
+				      mac_list);
+	if (!node) {
+		WARN_ONCE(1, "HSR: No self node\n");
+		return false;
 	}
 
-	return NULL;
-}
+	if (ether_addr_equal(addr, node->MacAddressA))
+		return true;
+	if (ether_addr_equal(addr, node->MacAddressB))
+		return true;
 
+	return false;
+}
 
 /* Search for mac entry. Caller must hold rcu read lock.
  */
-struct hsr_node *hsr_find_node(struct list_head *node_db, struct sk_buff *skb)
+static struct hsr_node *find_node_by_AddrA(struct list_head *node_db,
+					   const unsigned char addr[ETH_ALEN])
 {
 	struct hsr_node *node;
-	struct ethhdr *ethhdr;
-
-	if (!skb_mac_header_was_set(skb))
-		return NULL;
-
-	ethhdr = (struct ethhdr *) skb_mac_header(skb);
 
 	list_for_each_entry_rcu(node, node_db, mac_list) {
-		if (ether_addr_equal(node->MacAddressA, ethhdr->h_source))
-			return node;
-		if (ether_addr_equal(node->MacAddressB, ethhdr->h_source))
+		if (ether_addr_equal(node->MacAddressA, addr))
 			return node;
 	}
 
@@ -127,90 +125,22 @@ int hsr_create_self_node(struct list_head *self_node_db,
 }
 
 
-/* Add/merge node to the database of nodes. 'skb' must contain an HSR
- * supervision frame.
- * - If the supervision header's MacAddressA field is not yet in the database,
- * this frame is from an hitherto unknown node - add it to the database.
- * - If the sender's MAC address is not the same as its MacAddressA address,
- * the node is using PICS_SUBS (address substitution). Record the sender's
- * address as the node's MacAddressB.
- *
- * This function needs to work even if the sender node has changed one of its
- * slaves' MAC addresses. In this case, there are four different cases described
- * by (Addr-changed, received-from) pairs as follows. Note that changing the
- * SlaveA address is equal to changing the node's own address:
- *
- * - (AddrB, SlaveB): The new AddrB will be recorded by PICS_SUBS code since
- *		      node == NULL.
- * - (AddrB, SlaveA): Will work as usual (the AddrB change won't be detected
- *		      from this frame).
- *
- * - (AddrA, SlaveB): The old node will be found. We need to detect this and
- *		      remove the node.
- * - (AddrA, SlaveA): A new node will be registered (non-PICS_SUBS at first).
- *		      The old one will be pruned after HSR_NODE_FORGET_TIME.
- *
- * We also need to detect if the sender's SlaveA and SlaveB cables have been
- * swapped.
+/* Allocate an hsr_node and add it to node_db. 'addr' is the node's AddressA;
+ * seq_out is used to initialize filtering of outgoing duplicate frames
+ * originating from the newly added node.
  */
-struct hsr_node *hsr_merge_node(struct hsr_node *node, struct sk_buff *skb,
-				struct hsr_port *port)
+struct hsr_node *hsr_add_node(struct list_head *node_db, unsigned char addr[],
+			      u16 seq_out)
 {
-	struct hsr_priv *hsr;
-	struct hsr_sup_payload *hsr_sp;
-	struct hsr_ethhdr_sp *hsr_ethsup;
-	int i;
+	struct hsr_node *node;
 	unsigned long now;
-
-	hsr_ethsup = (struct hsr_ethhdr_sp *) skb_mac_header(skb);
-	hsr_sp = (struct hsr_sup_payload *) skb->data;
-	hsr = port->hsr;
-
-	if (node && !ether_addr_equal(node->MacAddressA, hsr_sp->MacAddressA)) {
-		/* Node has changed its AddrA, frame was received from SlaveB */
-		list_del_rcu(&node->mac_list);
-		kfree_rcu(node, rcu_head);
-		node = NULL;
-	}
-
-	if (node && (port->type == node->AddrB_port) &&
-	    !ether_addr_equal(node->MacAddressB, hsr_ethsup->ethhdr.h_source)) {
-		/* Cables have been swapped */
-		list_del_rcu(&node->mac_list);
-		kfree_rcu(node, rcu_head);
-		node = NULL;
-	}
-
-	if (node && (port->type != node->AddrB_port) &&
-	    (node->AddrB_port != HSR_PT_NONE) &&
-	    !ether_addr_equal(node->MacAddressA, hsr_ethsup->ethhdr.h_source)) {
-		/* Cables have been swapped */
-		list_del_rcu(&node->mac_list);
-		kfree_rcu(node, rcu_head);
-		node = NULL;
-	}
-
-	if (node)
-		return node;
-
-	node = find_node_by_AddrA(&hsr->node_db, hsr_sp->MacAddressA);
-	if (node) {
-		/* Node is known, but frame was received from an unknown
-		 * address. Node is PICS_SUBS capable; merge its AddrB.
-		 */
-		ether_addr_copy(node->MacAddressB, hsr_ethsup->ethhdr.h_source);
-		node->AddrB_port = port->type;
-		return node;
-	}
+	int i;
 
 	node = kzalloc(sizeof(*node), GFP_ATOMIC);
 	if (!node)
 		return NULL;
 
-	ether_addr_copy(node->MacAddressA, hsr_sp->MacAddressA);
-	ether_addr_copy(node->MacAddressB, hsr_ethsup->ethhdr.h_source);
-	if (!ether_addr_equal(hsr_sp->MacAddressA, hsr_ethsup->ethhdr.h_source))
-		node->AddrB_port = port->type;
+	ether_addr_copy(node->MacAddressA, addr);
 
 	/* We are only interested in time diffs here, so use current jiffies
 	 * as initialization. (0 could trigger an spurious ring error warning).
@@ -219,41 +149,120 @@ struct hsr_node *hsr_merge_node(struct hsr_node *node, struct sk_buff *skb,
 	for (i = 0; i < HSR_PT_PORTS; i++)
 		node->time_in[i] = now;
 	for (i = 0; i < HSR_PT_PORTS; i++)
-		node->seq_out[i] = ntohs(hsr_ethsup->hsr_sup.sequence_nr) - 1;
+		node->seq_out[i] = seq_out;
 
-	list_add_tail_rcu(&node->mac_list, &hsr->node_db);
+	list_add_tail_rcu(&node->mac_list, node_db);
 
 	return node;
 }
 
+/* Get the hsr_node from which 'skb' was sent.
+ */
+struct hsr_node *hsr_get_node(struct list_head *node_db, struct sk_buff *skb,
+			      bool is_sup)
+{
+	struct hsr_node *node;
+	struct ethhdr *ethhdr;
+	u16 seq_out;
+
+	if (!skb_mac_header_was_set(skb))
+		return NULL;
+
+	ethhdr = (struct ethhdr *) skb_mac_header(skb);
+
+	list_for_each_entry_rcu(node, node_db, mac_list) {
+		if (ether_addr_equal(node->MacAddressA, ethhdr->h_source))
+			return node;
+		if (ether_addr_equal(node->MacAddressB, ethhdr->h_source))
+			return node;
+	}
+
+	if (!is_sup)
+		return NULL; /* Only supervision frame may create node entry */
+
+	if (ethhdr->h_proto == htons(ETH_P_PRP)) {
+		/* Use the existing sequence_nr from the tag as starting point
+		 * for filtering duplicate frames.
+		 */
+		seq_out = hsr_get_skb_sequence_nr(skb) - 1;
+	} else {
+		WARN_ONCE(1, "%s: Non-HSR frame\n", __func__);
+		seq_out = 0;
+	}
+
+	return hsr_add_node(node_db, ethhdr->h_source, seq_out);
+}
+
+/* Use the Supervision frame's info about an eventual MacAddressB for merging
+ * nodes that has previously had their MacAddressB registered as a separate
+ * node.
+ */
+void hsr_handle_sup_frame(struct sk_buff *skb, struct hsr_node *node_curr,
+			  struct hsr_port *port_rcv)
+{
+	struct hsr_node *node_real;
+	struct hsr_sup_payload *hsr_sp;
+	struct list_head *node_db;
+	int i;
+
+	skb_pull(skb, sizeof(struct hsr_ethhdr_sp));
+	hsr_sp = (struct hsr_sup_payload *) skb->data;
+
+	if (ether_addr_equal(eth_hdr(skb)->h_source, hsr_sp->MacAddressA))
+		/* Not sent from MacAddressB of a PICS_SUBS capable node */
+		goto done;
+
+	/* Merge node_curr (registered on MacAddressB) into node_real */
+	node_db = &port_rcv->hsr->node_db;
+	node_real = find_node_by_AddrA(node_db, hsr_sp->MacAddressA);
+	if (!node_real)
+		/* No frame received from AddrA of this node yet */
+		node_real = hsr_add_node(node_db, hsr_sp->MacAddressA,
+					 HSR_SEQNR_START - 1);
+	if (!node_real)
+		goto done; /* No mem */
+	if (node_real == node_curr)
+		/* Node has already been merged */
+		goto done;
+
+	ether_addr_copy(node_real->MacAddressB, eth_hdr(skb)->h_source);
+	for (i = 0; i < HSR_PT_PORTS; i++) {
+		if (!node_curr->time_in_stale[i] &&
+		    time_after(node_curr->time_in[i], node_real->time_in[i])) {
+			node_real->time_in[i] = node_curr->time_in[i];
+			node_real->time_in_stale[i] = node_curr->time_in_stale[i];
+		}
+		if (seq_nr_after(node_curr->seq_out[i], node_real->seq_out[i]))
+			node_real->seq_out[i] = node_curr->seq_out[i];
+	}
+	node_real->AddrB_port = port_rcv->type;
+
+	list_del_rcu(&node_curr->mac_list);
+	kfree_rcu(node_curr, rcu_head);
+
+done:
+	skb_push(skb, sizeof(struct hsr_ethhdr_sp));
+}
+
 
 /* 'skb' is a frame meant for this host, that is to be passed to upper layers.
  *
- * If the frame was sent by a node's B interface, replace the sender
+ * If the frame was sent by a node's B interface, replace the source
  * address with that node's "official" address (MacAddressA) so that upper
  * layers recognize where it came from.
  */
-void hsr_addr_subst_source(struct hsr_priv *hsr, struct sk_buff *skb)
+void hsr_addr_subst_source(struct hsr_node *node, struct sk_buff *skb)
 {
-	struct ethhdr *ethhdr;
-	struct hsr_node *node;
-
 	if (!skb_mac_header_was_set(skb)) {
 		WARN_ONCE(1, "%s: Mac header not set\n", __func__);
 		return;
 	}
-	ethhdr = (struct ethhdr *) skb_mac_header(skb);
 
-	rcu_read_lock();
-	node = find_node_by_AddrB(&hsr->node_db, ethhdr->h_source);
-	if (node)
-		ether_addr_copy(ethhdr->h_source, node->MacAddressA);
-	rcu_read_unlock();
+	memcpy(&eth_hdr(skb)->h_source, node->MacAddressA, ETH_ALEN);
 }
 
-
 /* 'skb' is a frame meant for another host.
- * 'hsr_dev_idx' is the HSR index of the outgoing device
+ * 'port' is the outgoing interface
  *
  * Substitute the target (dest) MAC address if necessary, so the it matches the
  * recipient interface MAC address, regardless of whether that is the
@@ -261,44 +270,49 @@ void hsr_addr_subst_source(struct hsr_priv *hsr, struct sk_buff *skb)
  * This is needed to keep the packets flowing through switches that learn on
  * which "side" the different interfaces are.
  */
-void hsr_addr_subst_dest(struct hsr_priv *hsr, struct ethhdr *ethhdr,
+void hsr_addr_subst_dest(struct hsr_node *node_src, struct sk_buff *skb,
 			 struct hsr_port *port)
 {
-	struct hsr_node *node;
+	struct hsr_node *node_dst;
 
-	rcu_read_lock();
-	node = find_node_by_AddrA(&hsr->node_db, ethhdr->h_dest);
-	if (node && (node->AddrB_port == port->type))
-		ether_addr_copy(ethhdr->h_dest, node->MacAddressB);
-	rcu_read_unlock();
-}
+	if (!skb_mac_header_was_set(skb)) {
+		WARN_ONCE(1, "%s: Mac header not set\n", __func__);
+		return;
+	}
 
+	if (!is_unicast_ether_addr(eth_hdr(skb)->h_dest))
+		return;
 
-/* seq_nr_after(a, b) - return true if a is after (higher in sequence than) b,
- * false otherwise.
- */
-static bool seq_nr_after(u16 a, u16 b)
-{
-	/* Remove inconsistency where
-	 * seq_nr_after(a, b) == seq_nr_before(a, b)
-	 */
-	if ((int) b - a == 32768)
-		return false;
+	node_dst = find_node_by_AddrA(&port->hsr->node_db, eth_hdr(skb)->h_dest);
+	if (!node_dst) {
+		WARN_ONCE(1, "%s: Unknown node\n", __func__);
+		return;
+	}
+	if (port->type != node_dst->AddrB_port)
+		return;
+	if (!node_dst->MacAddressB) {
+		WARN_ONCE(1, "%s: No MacAddressB\n", __func__);
+		return;
+	}
 
-	return (((s16) (b - a)) < 0);
+	ether_addr_copy(eth_hdr(skb)->h_dest, node_dst->MacAddressB);
 }
-#define seq_nr_before(a, b)		seq_nr_after((b), (a))
-#define seq_nr_after_or_eq(a, b)	(!seq_nr_before((a), (b)))
-#define seq_nr_before_or_eq(a, b)	(!seq_nr_after((a), (b)))
 
 
-void hsr_register_frame_in(struct hsr_node *node, struct hsr_port *port)
+void hsr_register_frame_in(struct hsr_node *node, struct hsr_port *port,
+			   u16 sequence_nr)
 {
+	/* Don't register incoming frames without a valid sequence number. This
+	 * ensures entries of restarted nodes gets pruned so that they can
+	 * re-register and resume communications.
+	 */
+	if (seq_nr_before(sequence_nr, node->seq_out[port->type]))
+		return;
+
 	node->time_in[port->type] = jiffies;
 	node->time_in_stale[port->type] = false;
 }
 
-
 /* 'skb' is a HSR Ethernet frame (with a HSR tag inserted), with a valid
  * ethhdr->h_source address and skb->mac_header set.
  *
@@ -307,19 +321,9 @@ void hsr_register_frame_in(struct hsr_node *node, struct hsr_port *port)
  *	 0 otherwise, or
  *	 negative error code on error
  */
-int hsr_register_frame_out(struct hsr_node *node, struct hsr_port *port,
-			   struct sk_buff *skb)
+int hsr_register_frame_out(struct hsr_port *port, struct hsr_node *node,
+			   u16 sequence_nr)
 {
-	struct hsr_ethhdr *hsr_ethhdr;
-	u16 sequence_nr;
-
-	if (!skb_mac_header_was_set(skb)) {
-		WARN_ONCE(1, "%s: Mac header not set\n", __func__);
-		return -EINVAL;
-	}
-	hsr_ethhdr = (struct hsr_ethhdr *) skb_mac_header(skb);
-
-	sequence_nr = ntohs(hsr_ethhdr->hsr_tag.sequence_nr);
 	if (seq_nr_before_or_eq(sequence_nr, node->seq_out[port->type]))
 		return 1;