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>

Author: Arvid Brodin

net/hsr/Makefile

@@ -4,5 +4,5 @@
 
 obj-$(CONFIG_HSR)	+= hsr.o
 
-hsr-y			:= hsr_main.o hsr_framereg.o hsr_device.o hsr_netlink.o \
-			   hsr_slave.o
+hsr-y			:= hsr_main.o hsr_framereg.o hsr_device.o \
+			   hsr_netlink.o hsr_slave.o hsr_forward.o

net/hsr/hsr_device.c

@@ -21,6 +21,7 @@
 #include "hsr_slave.h"
 #include "hsr_framereg.h"
 #include "hsr_main.h"
+#include "hsr_forward.h"
 
 
 static bool is_admin_up(struct net_device *dev)
@@ -231,141 +232,21 @@ static netdev_features_t hsr_fix_features(struct net_device *dev,
 }
 
 
-static void hsr_fill_tag(struct hsr_ethhdr *hsr_ethhdr, struct hsr_priv *hsr)
-{
-	unsigned long irqflags;
-
-	/* IEC 62439-1:2010, p 48, says the 4-bit "path" field can take values
-	 * between 0001-1001 ("ring identifier", for regular HSR frames),
-	 * or 1111 ("HSR management", supervision frames). Unfortunately, the
-	 * spec writers forgot to explain what a "ring identifier" is, or
-	 * how it is used. So we just set this to 0001 for regular frames,
-	 * and 1111 for supervision frames.
-	 */
-	set_hsr_tag_path(&hsr_ethhdr->hsr_tag, 0x1);
-
-	/* IEC 62439-1:2010, p 12: "The link service data unit in an Ethernet
-	 * frame is the content of the frame located between the Length/Type
-	 * field and the Frame Check Sequence."
-	 *
-	 * IEC 62439-3, p 48, specifies the "original LPDU" to include the
-	 * original "LT" field (what "LT" means is not explained anywhere as
-	 * far as I can see - perhaps "Length/Type"?). So LSDU_size might
-	 * equal original length + 2.
-	 *   Also, the fact that this field is not used anywhere (might be used
-	 * by a RedBox connecting HSR and PRP nets?) means I cannot test its
-	 * correctness. Instead of guessing, I set this to 0 here, to make any
-	 * problems immediately apparent. Anyone using this driver with PRP/HSR
-	 * RedBoxes might need to fix this...
-	 */
-	set_hsr_tag_LSDU_size(&hsr_ethhdr->hsr_tag, 0);
-
-	spin_lock_irqsave(&hsr->seqnr_lock, irqflags);
-	hsr_ethhdr->hsr_tag.sequence_nr = htons(hsr->sequence_nr);
-	hsr->sequence_nr++;
-	spin_unlock_irqrestore(&hsr->seqnr_lock, irqflags);
-
-	hsr_ethhdr->hsr_tag.encap_proto = hsr_ethhdr->ethhdr.h_proto;
-
-	hsr_ethhdr->ethhdr.h_proto = htons(ETH_P_PRP);
-}
-
-static int slave_xmit(struct hsr_priv *hsr, struct sk_buff *skb,
-		      enum hsr_port_type type)
-{
-	struct hsr_port *port;
-	struct hsr_ethhdr *hsr_ethhdr;
-
-	hsr_ethhdr = (struct hsr_ethhdr *) skb->data;
-
-	rcu_read_lock();
-	port = hsr_port_get_hsr(hsr, type);
-	if (!port) {
-		rcu_read_unlock();
-		return NET_XMIT_DROP;
-	}
-	skb->dev = port->dev;
-
-	hsr_addr_subst_dest(port->hsr, &hsr_ethhdr->ethhdr, port);
-	rcu_read_unlock();
-
-	/* Address substitution (IEC62439-3 pp 26, 50): replace mac
-	 * address of outgoing frame with that of the outgoing slave's.
-	 */
-	ether_addr_copy(hsr_ethhdr->ethhdr.h_source, skb->dev->dev_addr);
-
-	return dev_queue_xmit(skb);
-}
-
 static int hsr_dev_xmit(struct sk_buff *skb, struct net_device *dev)
 {
-	struct hsr_priv *hsr;
+	struct hsr_priv *hsr = netdev_priv(dev);
 	struct hsr_port *master;
-	struct hsr_ethhdr *hsr_ethhdr;
-	struct sk_buff *skb2;
-	int res1, res2;
-
-	hsr = netdev_priv(dev);
-	hsr_ethhdr = (struct hsr_ethhdr *) skb->data;
-
-	if ((skb->protocol != htons(ETH_P_PRP)) ||
-	    (hsr_ethhdr->ethhdr.h_proto != htons(ETH_P_PRP))) {
-		hsr_fill_tag(hsr_ethhdr, hsr);
-		skb->protocol = htons(ETH_P_PRP);
-	}
 
-	skb2 = pskb_copy(skb, GFP_ATOMIC);
-
-	res1 = slave_xmit(hsr, skb, HSR_PT_SLAVE_A);
-	if (skb2)
-		res2 = slave_xmit(hsr, skb2, HSR_PT_SLAVE_B);
-	else
-		res2 = NET_XMIT_DROP;
-
-	rcu_read_lock();
 	master = hsr_port_get_hsr(hsr, HSR_PT_MASTER);
-	if (likely(res1 == NET_XMIT_SUCCESS || res1 == NET_XMIT_CN ||
-		   res2 == NET_XMIT_SUCCESS || res2 == NET_XMIT_CN)) {
-		master->dev->stats.tx_packets++;
-		master->dev->stats.tx_bytes += skb->len;
-	} else {
-		master->dev->stats.tx_dropped++;
-	}
-	rcu_read_unlock();
+	skb->dev = master->dev;
+	hsr_forward_skb(skb, master);
 
 	return NETDEV_TX_OK;
 }
 
 
-static int hsr_header_create(struct sk_buff *skb, struct net_device *dev,
-			     unsigned short type, const void *daddr,
-			     const void *saddr, unsigned int len)
-{
-	int res;
-
-	/* Make room for the HSR tag now. We will fill it in later (in
-	 * hsr_dev_xmit)
-	 */
-	if (skb_headroom(skb) < HSR_HLEN + ETH_HLEN)
-		return -ENOBUFS;
-	skb_push(skb, HSR_HLEN);
-
-	/* To allow VLAN/HSR combos we should probably use
-	 * res = dev_hard_header(skb, dev, type, daddr, saddr, len + HSR_HLEN);
-	 * here instead. It would require other changes too, though - e.g.
-	 * separate headers for each slave etc...
-	 */
-	res = eth_header(skb, dev, type, daddr, saddr, len + HSR_HLEN);
-	if (res <= 0)
-		return res;
-	skb_reset_mac_header(skb);
-
-	return res + HSR_HLEN;
-}
-
-
 static const struct header_ops hsr_header_ops = {
-	.create	 = hsr_header_create,
+	.create	 = eth_header,
 	.parse	 = eth_header_parse,
 };
 
@@ -382,19 +263,13 @@ static int hsr_pad(int size)
 	return min_size;
 }
 
-static void send_hsr_supervision_frame(struct net_device *hsr_dev, u8 type)
+static void send_hsr_supervision_frame(struct hsr_port *master, u8 type)
 {
-	struct hsr_priv *hsr;
-	struct hsr_port *master;
 	struct sk_buff *skb;
 	int hlen, tlen;
 	struct hsr_sup_tag *hsr_stag;
 	struct hsr_sup_payload *hsr_sp;
 	unsigned long irqflags;
-	int res;
-
-	hsr = netdev_priv(hsr_dev);
-	master = hsr_port_get_hsr(hsr, HSR_PT_MASTER);
 
 	hlen = LL_RESERVED_SPACE(master->dev);
 	tlen = master->dev->needed_tailroom;
@@ -410,33 +285,30 @@ static void send_hsr_supervision_frame(struct net_device *hsr_dev, u8 type)
 	skb->protocol = htons(ETH_P_PRP);
 	skb->priority = TC_PRIO_CONTROL;
 
-	res = dev_hard_header(skb, skb->dev, ETH_P_PRP,
-			      hsr->sup_multicast_addr,
-			      skb->dev->dev_addr, skb->len);
-	if (res <= 0)
+	if (dev_hard_header(skb, skb->dev, ETH_P_PRP,
+			    master->hsr->sup_multicast_addr,
+			    skb->dev->dev_addr, skb->len) <= 0)
 		goto out;
+	skb_reset_mac_header(skb);
 
-	skb_pull(skb, sizeof(struct ethhdr));
-	hsr_stag = (typeof(hsr_stag)) skb->data;
+	hsr_stag = (typeof(hsr_stag)) skb_put(skb, sizeof(*hsr_stag));
 
 	set_hsr_stag_path(hsr_stag, 0xf);
 	set_hsr_stag_HSR_Ver(hsr_stag, 0);
 
-	spin_lock_irqsave(&hsr->seqnr_lock, irqflags);
-	hsr_stag->sequence_nr = htons(hsr->sequence_nr);
-	hsr->sequence_nr++;
-	spin_unlock_irqrestore(&hsr->seqnr_lock, irqflags);
+	spin_lock_irqsave(&master->hsr->seqnr_lock, irqflags);
+	hsr_stag->sequence_nr = htons(master->hsr->sequence_nr);
+	master->hsr->sequence_nr++;
+	spin_unlock_irqrestore(&master->hsr->seqnr_lock, irqflags);
 
 	hsr_stag->HSR_TLV_Type = type;
 	hsr_stag->HSR_TLV_Length = 12;
 
-	skb_push(skb, sizeof(struct ethhdr));
-
 	/* Payload: MacAddressA */
 	hsr_sp = (typeof(hsr_sp)) skb_put(skb, sizeof(*hsr_sp));
 	ether_addr_copy(hsr_sp->MacAddressA, master->dev->dev_addr);
 
-	dev_queue_xmit(skb);
+	hsr_forward_skb(skb, master);
 	return;
 
 out:
@@ -453,13 +325,15 @@ static void hsr_announce(unsigned long data)
 	struct hsr_port *master;
 
 	hsr = (struct hsr_priv *) data;
+
+	rcu_read_lock();
 	master = hsr_port_get_hsr(hsr, HSR_PT_MASTER);
 
 	if (hsr->announce_count < 3) {
-		send_hsr_supervision_frame(master->dev, HSR_TLV_ANNOUNCE);
+		send_hsr_supervision_frame(master, HSR_TLV_ANNOUNCE);
 		hsr->announce_count++;
 	} else {
-		send_hsr_supervision_frame(master->dev, HSR_TLV_LIFE_CHECK);
+		send_hsr_supervision_frame(master, HSR_TLV_LIFE_CHECK);
 	}
 
 	if (hsr->announce_count < 3)
@@ -471,6 +345,8 @@ static void hsr_announce(unsigned long data)
 
 	if (is_admin_up(master->dev))
 		add_timer(&hsr->announce_timer);
+
+	rcu_read_unlock();
 }
 
 
@@ -570,7 +446,7 @@ int hsr_dev_finalize(struct net_device *hsr_dev, struct net_device *slave[2],
 
 	spin_lock_init(&hsr->seqnr_lock);
 	/* Overflow soon to find bugs easier: */
-	hsr->sequence_nr = USHRT_MAX - 1024;
+	hsr->sequence_nr = HSR_SEQNR_START;
 
 	init_timer(&hsr->announce_timer);
 	hsr->announce_timer.function = hsr_announce;