Merge branch 'cxgb4-l2-table-enhancements'

Hariprasad Shenai says:

====================
Few l2 table related enhancements for cxgb4

This series adds a new API to allocate and update l2t entry, replaces
arpq_head/arpq_tail with double skb double linked list. Use t4_mgmt_tx()
to send control packets of l2t write request. Use symbolic constants
while calculating vlan priority.

This patch series has been created against net-next tree and includes
patches on cxgb4 driver.

We have included all the maintainers of respective drivers. Kindly review
the change and let us know in case of any review comments.

Thanks

V2: Remove unnecessary MAS operation while calculating vlan prio in
    PATCH 1/4 ("cxgb4: Use symbolic constant for VLAN priority calculation")
    based on review comment by David Miller
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/chelsio/cxgb4/cxgb4_main.c

@@ -1181,15 +1181,9 @@ static int set_filter_wr(struct adapter *adapter, int fidx)
 	 */
 	if (f->fs.newdmac || f->fs.newvlan) {
 		/* allocate L2T entry for new filter */
-		f->l2t = t4_l2t_alloc_switching(adapter->l2t);
+		f->l2t = t4_l2t_alloc_switching(adapter, f->fs.vlan,
+						f->fs.eport, f->fs.dmac);
 		if (f->l2t == NULL) {
-			kfree_skb(skb);
-			return -EAGAIN;
-		}
-		if (t4_l2t_set_switching(adapter, f->l2t, f->fs.vlan,
-					f->fs.eport, f->fs.dmac)) {
-			cxgb4_l2t_release(f->l2t);
-			f->l2t = NULL;
 			kfree_skb(skb);
 			return -ENOMEM;
 		}

drivers/net/ethernet/chelsio/cxgb4/l2t.c

@@ -66,7 +66,7 @@ struct l2t_data {
 
 static inline unsigned int vlan_prio(const struct l2t_entry *e)
 {
-	return e->vlan >> 13;
+	return e->vlan >> VLAN_PRIO_SHIFT;
 }
 
 static inline void l2t_hold(struct l2t_data *d, struct l2t_entry *e)
@@ -161,8 +161,7 @@ static int write_l2e(struct adapter *adap, struct l2t_entry *e, int sync)
 		memcpy(e->dmac, e->neigh->ha, sizeof(e->dmac));
 	memcpy(req->dst_mac, e->dmac, sizeof(req->dst_mac));
 
-	set_wr_txq(skb, CPL_PRIORITY_CONTROL, 0);
-	t4_ofld_send(adap, skb);
+	t4_mgmt_tx(adap, skb);
 
 	if (sync && e->state != L2T_STATE_SWITCHING)
 		e->state = L2T_STATE_SYNC_WRITE;
@@ -175,14 +174,10 @@ static int write_l2e(struct adapter *adap, struct l2t_entry *e, int sync)
  */
 static void send_pending(struct adapter *adap, struct l2t_entry *e)
 {
-	while (e->arpq_head) {
-		struct sk_buff *skb = e->arpq_head;
+	struct sk_buff *skb;
 
-		e->arpq_head = skb->next;
-		skb->next = NULL;
+	while ((skb = __skb_dequeue(&e->arpq)) != NULL)
 		t4_ofld_send(adap, skb);
-	}
-	e->arpq_tail = NULL;
 }
 
 /*
@@ -222,12 +217,7 @@ void do_l2t_write_rpl(struct adapter *adap, const struct cpl_l2t_write_rpl *rpl)
  */
 static inline void arpq_enqueue(struct l2t_entry *e, struct sk_buff *skb)
 {
-	skb->next = NULL;
-	if (e->arpq_head)
-		e->arpq_tail->next = skb;
-	else
-		e->arpq_head = skb;
-	e->arpq_tail = skb;
+	__skb_queue_tail(&e->arpq, skb);
 }
 
 int cxgb4_l2t_send(struct net_device *dev, struct sk_buff *skb,
@@ -259,7 +249,8 @@ again:
 		if (e->state == L2T_STATE_RESOLVING &&
 		    !neigh_event_send(e->neigh, NULL)) {
 			spin_lock_bh(&e->lock);
-			if (e->state == L2T_STATE_RESOLVING && e->arpq_head)
+			if (e->state == L2T_STATE_RESOLVING &&
+			    !skb_queue_empty(&e->arpq))
 				write_l2e(adap, e, 1);
 			spin_unlock_bh(&e->lock);
 		}
@@ -305,12 +296,82 @@ found:
 	return e;
 }
 
-/*
- * Called when an L2T entry has no more users.
+static struct l2t_entry *find_or_alloc_l2e(struct l2t_data *d, u16 vlan,
+					   u8 port, u8 *dmac)
+{
+	struct l2t_entry *end, *e, **p;
+	struct l2t_entry *first_free = NULL;
+
+	for (e = &d->l2tab[0], end = &d->l2tab[d->l2t_size]; e != end; ++e) {
+		if (atomic_read(&e->refcnt) == 0) {
+			if (!first_free)
+				first_free = e;
+		} else {
+			if (e->state == L2T_STATE_SWITCHING) {
+				if (ether_addr_equal(e->dmac, dmac) &&
+				    (e->vlan == vlan) && (e->lport == port))
+					goto exists;
+			}
+		}
+	}
+
+	if (first_free) {
+		e = first_free;
+		goto found;
+	}
+
+	return NULL;
+
+found:
+	/* The entry we found may be an inactive entry that is
+	 * presently in the hash table.  We need to remove it.
+	 */
+	if (e->state < L2T_STATE_SWITCHING)
+		for (p = &d->l2tab[e->hash].first; *p; p = &(*p)->next)
+			if (*p == e) {
+				*p = e->next;
+				e->next = NULL;
+				break;
+			}
+	e->state = L2T_STATE_UNUSED;
+
+exists:
+	return e;
+}
+
+/* Called when an L2T entry has no more users.  The entry is left in the hash
+ * table since it is likely to be reused but we also bump nfree to indicate
+ * that the entry can be reallocated for a different neighbor.  We also drop
+ * the existing neighbor reference in case the neighbor is going away and is
+ * waiting on our reference.
+ *
+ * Because entries can be reallocated to other neighbors once their ref count
+ * drops to 0 we need to take the entry's lock to avoid races with a new
+ * incarnation.
  */
+static void _t4_l2e_free(struct l2t_entry *e)
+{
+	struct l2t_data *d;
+	struct sk_buff *skb;
+
+	if (atomic_read(&e->refcnt) == 0) {  /* hasn't been recycled */
+		if (e->neigh) {
+			neigh_release(e->neigh);
+			e->neigh = NULL;
+		}
+		while ((skb = __skb_dequeue(&e->arpq)) != NULL)
+			kfree_skb(skb);
+	}
+
+	d = container_of(e, struct l2t_data, l2tab[e->idx]);
+	atomic_inc(&d->nfree);
+}
+
+/* Locked version of _t4_l2e_free */
 static void t4_l2e_free(struct l2t_entry *e)
 {
 	struct l2t_data *d;
+	struct sk_buff *skb;
 
 	spin_lock_bh(&e->lock);
 	if (atomic_read(&e->refcnt) == 0) {  /* hasn't been recycled */
@@ -318,13 +379,8 @@ static void t4_l2e_free(struct l2t_entry *e)
 			neigh_release(e->neigh);
 			e->neigh = NULL;
 		}
-		while (e->arpq_head) {
-			struct sk_buff *skb = e->arpq_head;
-
-			e->arpq_head = skb->next;
+		while ((skb = __skb_dequeue(&e->arpq)) != NULL)
 			kfree_skb(skb);
-		}
-		e->arpq_tail = NULL;
 	}
 	spin_unlock_bh(&e->lock);
 
@@ -457,18 +513,19 @@ EXPORT_SYMBOL(cxgb4_select_ntuple);
  * on the arpq head.  If a packet specifies a failure handler it is invoked,
  * otherwise the packet is sent to the device.
  */
-static void handle_failed_resolution(struct adapter *adap, struct sk_buff *arpq)
+static void handle_failed_resolution(struct adapter *adap, struct l2t_entry *e)
 {
-	while (arpq) {
-		struct sk_buff *skb = arpq;
+	struct sk_buff *skb;
+
+	while ((skb = __skb_dequeue(&e->arpq)) != NULL) {
 		const struct l2t_skb_cb *cb = L2T_SKB_CB(skb);
 
-		arpq = skb->next;
-		skb->next = NULL;
+		spin_unlock(&e->lock);
 		if (cb->arp_err_handler)
 			cb->arp_err_handler(cb->handle, skb);
 		else
 			t4_ofld_send(adap, skb);
+		spin_lock(&e->lock);
 	}
 }
 
@@ -479,7 +536,7 @@ static void handle_failed_resolution(struct adapter *adap, struct sk_buff *arpq)
 void t4_l2t_update(struct adapter *adap, struct neighbour *neigh)
 {
 	struct l2t_entry *e;
-	struct sk_buff *arpq = NULL;
+	struct sk_buff_head *arpq = NULL;
 	struct l2t_data *d = adap->l2t;
 	int addr_len = neigh->tbl->key_len;
 	u32 *addr = (u32 *) neigh->primary_key;
@@ -506,10 +563,9 @@ void t4_l2t_update(struct adapter *adap, struct neighbour *neigh)
 
 	if (e->state == L2T_STATE_RESOLVING) {
 		if (neigh->nud_state & NUD_FAILED) {
-			arpq = e->arpq_head;
-			e->arpq_head = e->arpq_tail = NULL;
+			arpq = &e->arpq;
 		} else if ((neigh->nud_state & (NUD_CONNECTED | NUD_STALE)) &&
-			   e->arpq_head) {
+			   !skb_queue_empty(&e->arpq)) {
 			write_l2e(adap, e, 1);
 		}
 	} else {
@@ -519,43 +575,66 @@ void t4_l2t_update(struct adapter *adap, struct neighbour *neigh)
 			write_l2e(adap, e, 0);
 	}
 
-	spin_unlock_bh(&e->lock);
-
 	if (arpq)
-		handle_failed_resolution(adap, arpq);
+		handle_failed_resolution(adap, e);
+	spin_unlock_bh(&e->lock);
 }
 
 /* Allocate an L2T entry for use by a switching rule.  Such need to be
  * explicitly freed and while busy they are not on any hash chain, so normal
  * address resolution updates do not see them.
  */
-struct l2t_entry *t4_l2t_alloc_switching(struct l2t_data *d)
+struct l2t_entry *t4_l2t_alloc_switching(struct adapter *adap, u16 vlan,
+					 u8 port, u8 *eth_addr)
 {
+	struct l2t_data *d = adap->l2t;
 	struct l2t_entry *e;
+	int ret;
 
 	write_lock_bh(&d->lock);
-	e = alloc_l2e(d);
+	e = find_or_alloc_l2e(d, vlan, port, eth_addr);
 	if (e) {
 		spin_lock(&e->lock);          /* avoid race with t4_l2t_free */
-		e->state = L2T_STATE_SWITCHING;
-		atomic_set(&e->refcnt, 1);
+		if (!atomic_read(&e->refcnt)) {
+			e->state = L2T_STATE_SWITCHING;
+			e->vlan = vlan;
+			e->lport = port;
+			ether_addr_copy(e->dmac, eth_addr);
+			atomic_set(&e->refcnt, 1);
+			ret = write_l2e(adap, e, 0);
+			if (ret < 0) {
+				_t4_l2e_free(e);
+				spin_unlock(&e->lock);
+				write_unlock_bh(&d->lock);
+				return NULL;
+			}
+		} else {
+			atomic_inc(&e->refcnt);
+		}
+
 		spin_unlock(&e->lock);
 	}
 	write_unlock_bh(&d->lock);
 	return e;
 }
 
-/* Sets/updates the contents of a switching L2T entry that has been allocated
- * with an earlier call to @t4_l2t_alloc_switching.
+/**
+ * @dev: net_device pointer
+ * @vlan: VLAN Id
+ * @port: Associated port
+ * @dmac: Destination MAC address to add to L2T
+ * Returns pointer to the allocated l2t entry
+ *
+ * Allocates an L2T entry for use by switching rule of a filter
  */
-int t4_l2t_set_switching(struct adapter *adap, struct l2t_entry *e, u16 vlan,
-		u8 port, u8 *eth_addr)
+struct l2t_entry *cxgb4_l2t_alloc_switching(struct net_device *dev, u16 vlan,
+					    u8 port, u8 *dmac)
 {
-	e->vlan = vlan;
-	e->lport = port;
-	memcpy(e->dmac, eth_addr, ETH_ALEN);
-	return write_l2e(adap, e, 0);
+	struct adapter *adap = netdev2adap(dev);
+
+	return t4_l2t_alloc_switching(adap, vlan, port, dmac);
 }
+EXPORT_SYMBOL(cxgb4_l2t_alloc_switching);
 
 struct l2t_data *t4_init_l2t(unsigned int l2t_start, unsigned int l2t_end)
 {
@@ -585,6 +664,7 @@ struct l2t_data *t4_init_l2t(unsigned int l2t_start, unsigned int l2t_end)
 		d->l2tab[i].state = L2T_STATE_UNUSED;
 		spin_lock_init(&d->l2tab[i].lock);
 		atomic_set(&d->l2tab[i].refcnt, 0);
+		skb_queue_head_init(&d->l2tab[i].arpq);
 	}
 	return d;
 }
@@ -619,7 +699,8 @@ static char l2e_state(const struct l2t_entry *e)
 	case L2T_STATE_VALID: return 'V';
 	case L2T_STATE_STALE: return 'S';
 	case L2T_STATE_SYNC_WRITE: return 'W';
-	case L2T_STATE_RESOLVING: return e->arpq_head ? 'A' : 'R';
+	case L2T_STATE_RESOLVING:
+		return skb_queue_empty(&e->arpq) ? 'R' : 'A';
 	case L2T_STATE_SWITCHING: return 'X';
 	default:
 		return 'U';

drivers/net/ethernet/chelsio/cxgb4/l2t.h

@@ -76,8 +76,7 @@ struct l2t_entry {
 	struct neighbour *neigh;    /* associated neighbour */
 	struct l2t_entry *first;    /* start of hash chain */
 	struct l2t_entry *next;     /* next l2t_entry on chain */
-	struct sk_buff *arpq_head;  /* queue of packets awaiting resolution */
-	struct sk_buff *arpq_tail;
+	struct sk_buff_head arpq;   /* packet queue awaiting resolution */
 	spinlock_t lock;
 	atomic_t refcnt;            /* entry reference count */
 	u16 hash;                   /* hash bucket the entry is on */
@@ -114,10 +113,11 @@ struct l2t_entry *cxgb4_l2t_get(struct l2t_data *d, struct neighbour *neigh,
 				unsigned int priority);
 u64 cxgb4_select_ntuple(struct net_device *dev,
 			const struct l2t_entry *l2t);
+struct l2t_entry *cxgb4_l2t_alloc_switching(struct net_device *dev, u16 vlan,
+					    u8 port, u8 *dmac);
 void t4_l2t_update(struct adapter *adap, struct neighbour *neigh);
-struct l2t_entry *t4_l2t_alloc_switching(struct l2t_data *d);
-int t4_l2t_set_switching(struct adapter *adap, struct l2t_entry *e, u16 vlan,
-			 u8 port, u8 *eth_addr);
+struct l2t_entry *t4_l2t_alloc_switching(struct adapter *adap, u16 vlan,
+					 u8 port, u8 *dmac);
 struct l2t_data *t4_init_l2t(unsigned int l2t_start, unsigned int l2t_end);
 void do_l2t_write_rpl(struct adapter *p, const struct cpl_l2t_write_rpl *rpl);