5 files changed, 87 insertions, 41 deletions

diff --git a/drivers/infiniband/hw/qib/qib.h b/drivers/infiniband/hw/qib/qib.h
index 97e6233..b881bdc 100644
--- a/drivers/infiniband/hw/qib/qib.h
+++ b/drivers/infiniband/hw/qib/qib.h
@@ -223,6 +223,9 @@ struct qib_ctxtdata {
 	/* ctxt rcvhdrq head offset */
 	u32 head;
 	u32 pkt_count;
+	/* lookaside fields */
+	struct qib_qp *lookaside_qp;
+	u32 lookaside_qpn;
 	/* QPs waiting for context processing */
 	struct list_head qp_wait_list;
 };
diff --git a/drivers/infiniband/hw/qib/qib_driver.c b/drivers/infiniband/hw/qib/qib_driver.c
index 89264ff..d35c9d3 100644
--- a/drivers/infiniband/hw/qib/qib_driver.c
+++ b/drivers/infiniband/hw/qib/qib_driver.c
@@ -547,6 +547,15 @@ move_along:
 			updegr = 0;
 		}
 	}
+	/*
+	 * Notify qib_destroy_qp() if it is waiting
+	 * for lookaside_qp to finish.
+	 */
+	if (rcd->lookaside_qp) {
+		if (atomic_dec_and_test(&rcd->lookaside_qp->refcount))
+			wake_up(&rcd->lookaside_qp->wait);
+		rcd->lookaside_qp = NULL;
+	}
 
 	rcd->head = l;
 	rcd->pkt_count += i;
diff --git a/drivers/infiniband/hw/qib/qib_qp.c b/drivers/infiniband/hw/qib/qib_qp.c
index 9d094f9..500981b 100644
--- a/drivers/infiniband/hw/qib/qib_qp.c
+++ b/drivers/infiniband/hw/qib/qib_qp.c
@@ -34,6 +34,7 @@
 
 #include <linux/err.h>
 #include <linux/vmalloc.h>
+#include <linux/jhash.h>
 
 #include "qib.h"
 
@@ -204,6 +205,13 @@ static void free_qpn(struct qib_qpn_table *qpt, u32 qpn)
 		clear_bit(qpn & BITS_PER_PAGE_MASK, map->page);
 }
 
+static inline unsigned qpn_hash(struct qib_ibdev *dev, u32 qpn)
+{
+	return jhash_1word(qpn, dev->qp_rnd) &
+		(dev->qp_table_size - 1);
+}
+
+
 /*
  * Put the QP into the hash table.
  * The hash table holds a reference to the QP.
@@ -211,22 +219,23 @@ static void free_qpn(struct qib_qpn_table *qpt, u32 qpn)
 static void insert_qp(struct qib_ibdev *dev, struct qib_qp *qp)
 {
 	struct qib_ibport *ibp = to_iport(qp->ibqp.device, qp->port_num);
-	unsigned n = qp->ibqp.qp_num % dev->qp_table_size;
 	unsigned long flags;
+	unsigned n = qpn_hash(dev, qp->ibqp.qp_num);
 
 	spin_lock_irqsave(&dev->qpt_lock, flags);
+	atomic_inc(&qp->refcount);
 
 	if (qp->ibqp.qp_num == 0)
-		ibp->qp0 = qp;
+		rcu_assign_pointer(ibp->qp0, qp);
 	else if (qp->ibqp.qp_num == 1)
-		ibp->qp1 = qp;
+		rcu_assign_pointer(ibp->qp1, qp);
 	else {
 		qp->next = dev->qp_table[n];
-		dev->qp_table[n] = qp;
+		rcu_assign_pointer(dev->qp_table[n], qp);
 	}
-	atomic_inc(&qp->refcount);
 
 	spin_unlock_irqrestore(&dev->qpt_lock, flags);
+	synchronize_rcu();
 }
 
 /*
@@ -236,29 +245,32 @@ static void insert_qp(struct qib_ibdev *dev, struct qib_qp *qp)
 static void remove_qp(struct qib_ibdev *dev, struct qib_qp *qp)
 {
 	struct qib_ibport *ibp = to_iport(qp->ibqp.device, qp->port_num);
-	struct qib_qp *q, **qpp;
+	unsigned n = qpn_hash(dev, qp->ibqp.qp_num);
 	unsigned long flags;
 
-	qpp = &dev->qp_table[qp->ibqp.qp_num % dev->qp_table_size];
-
 	spin_lock_irqsave(&dev->qpt_lock, flags);
 
 	if (ibp->qp0 == qp) {
-		ibp->qp0 = NULL;
 		atomic_dec(&qp->refcount);
+		rcu_assign_pointer(ibp->qp0, NULL);
 	} else if (ibp->qp1 == qp) {
-		ibp->qp1 = NULL;
 		atomic_dec(&qp->refcount);
-	} else
+		rcu_assign_pointer(ibp->qp1, NULL);
+	} else {
+		struct qib_qp *q, **qpp;
+
+		qpp = &dev->qp_table[n];
 		for (; (q = *qpp) != NULL; qpp = &q->next)
 			if (q == qp) {
-				*qpp = qp->next;
-				qp->next = NULL;
 				atomic_dec(&qp->refcount);
+				rcu_assign_pointer(*qpp, qp->next);
+				qp->next = NULL;
 				break;
 			}
+	}
 
 	spin_unlock_irqrestore(&dev->qpt_lock, flags);
+	synchronize_rcu();
 }
 
 /**
@@ -280,21 +292,24 @@ unsigned qib_free_all_qps(struct qib_devdata *dd)
 
 		if (!qib_mcast_tree_empty(ibp))
 			qp_inuse++;
-		if (ibp->qp0)
+		rcu_read_lock();
+		if (rcu_dereference(ibp->qp0))
 			qp_inuse++;
-		if (ibp->qp1)
+		if (rcu_dereference(ibp->qp1))
 			qp_inuse++;
+		rcu_read_unlock();
 	}
 
 	spin_lock_irqsave(&dev->qpt_lock, flags);
 	for (n = 0; n < dev->qp_table_size; n++) {
 		qp = dev->qp_table[n];
-		dev->qp_table[n] = NULL;
+		rcu_assign_pointer(dev->qp_table[n], NULL);
 
 		for (; qp; qp = qp->next)
 			qp_inuse++;
 	}
 	spin_unlock_irqrestore(&dev->qpt_lock, flags);
+	synchronize_rcu();
 
 	return qp_inuse;
 }
@@ -309,25 +324,28 @@ unsigned qib_free_all_qps(struct qib_devdata *dd)
  */
 struct qib_qp *qib_lookup_qpn(struct qib_ibport *ibp, u32 qpn)
 {
-	struct qib_ibdev *dev = &ppd_from_ibp(ibp)->dd->verbs_dev;
-	unsigned long flags;
-	struct qib_qp *qp;
+	struct qib_qp *qp = NULL;
 
-	spin_lock_irqsave(&dev->qpt_lock, flags);
+	if (unlikely(qpn <= 1)) {
+		rcu_read_lock();
+		if (qpn == 0)
+			qp = rcu_dereference(ibp->qp0);
+		else
+			qp = rcu_dereference(ibp->qp1);
+	} else {
+		struct qib_ibdev *dev = &ppd_from_ibp(ibp)->dd->verbs_dev;
+		unsigned n = qpn_hash(dev, qpn);
 
-	if (qpn == 0)
-		qp = ibp->qp0;
-	else if (qpn == 1)
-		qp = ibp->qp1;
-	else
-		for (qp = dev->qp_table[qpn % dev->qp_table_size]; qp;
-		     qp = qp->next)
+		rcu_read_lock();
+		for (qp = dev->qp_table[n]; rcu_dereference(qp); qp = qp->next)
 			if (qp->ibqp.qp_num == qpn)
 				break;
+	}
 	if (qp)
-		atomic_inc(&qp->refcount);
+		if (unlikely(!atomic_inc_not_zero(&qp->refcount)))
+			qp = NULL;
 
-	spin_unlock_irqrestore(&dev->qpt_lock, flags);
+	rcu_read_unlock();
 	return qp;
 }
 
@@ -1015,6 +1033,7 @@ struct ib_qp *qib_create_qp(struct ib_pd *ibpd,
 			ret = ERR_PTR(-ENOMEM);
 			goto bail_swq;
 		}
+		RCU_INIT_POINTER(qp->next, NULL);
 		if (init_attr->srq)
 			sz = 0;
 		else {
diff --git a/drivers/infiniband/hw/qib/qib_verbs.c b/drivers/infiniband/hw/qib/qib_verbs.c
index 9fab404..9627cb73 100644
--- a/drivers/infiniband/hw/qib/qib_verbs.c
+++ b/drivers/infiniband/hw/qib/qib_verbs.c
@@ -38,11 +38,12 @@
 #include <linux/utsname.h>
 #include <linux/rculist.h>
 #include <linux/mm.h>
+#include <linux/random.h>
 
 #include "qib.h"
 #include "qib_common.h"
 
-static unsigned int ib_qib_qp_table_size = 251;
+static unsigned int ib_qib_qp_table_size = 256;
 module_param_named(qp_table_size, ib_qib_qp_table_size, uint, S_IRUGO);
 MODULE_PARM_DESC(qp_table_size, "QP table size");
 
@@ -659,17 +660,25 @@ void qib_ib_rcv(struct qib_ctxtdata *rcd, void *rhdr, void *data, u32 tlen)
 		if (atomic_dec_return(&mcast->refcount) <= 1)
 			wake_up(&mcast->wait);
 	} else {
-		qp = qib_lookup_qpn(ibp, qp_num);
-		if (!qp)
-			goto drop;
+		if (rcd->lookaside_qp) {
+			if (rcd->lookaside_qpn != qp_num) {
+				if (atomic_dec_and_test(
+					&rcd->lookaside_qp->refcount))
+					wake_up(
+					 &rcd->lookaside_qp->wait);
+					rcd->lookaside_qp = NULL;
+				}
+		}
+		if (!rcd->lookaside_qp) {
+			qp = qib_lookup_qpn(ibp, qp_num);
+			if (!qp)
+				goto drop;
+			rcd->lookaside_qp = qp;
+			rcd->lookaside_qpn = qp_num;
+		} else
+			qp = rcd->lookaside_qp;
 		ibp->n_unicast_rcv++;
 		qib_qp_rcv(rcd, hdr, lnh == QIB_LRH_GRH, data, tlen, qp);
-		/*
-		 * Notify qib_destroy_qp() if it is waiting
-		 * for us to finish.
-		 */
-		if (atomic_dec_and_test(&qp->refcount))
-			wake_up(&qp->wait);
 	}
 	return;
 
@@ -1974,6 +1983,8 @@ static void init_ibport(struct qib_pportdata *ppd)
 	ibp->z_excessive_buffer_overrun_errors =
 		cntrs.excessive_buffer_overrun_errors;
 	ibp->z_vl15_dropped = cntrs.vl15_dropped;
+	RCU_INIT_POINTER(ibp->qp0, NULL);
+	RCU_INIT_POINTER(ibp->qp1, NULL);
 }
 
 /**
@@ -1990,12 +2001,15 @@ int qib_register_ib_device(struct qib_devdata *dd)
 	int ret;
 
 	dev->qp_table_size = ib_qib_qp_table_size;
-	dev->qp_table = kzalloc(dev->qp_table_size * sizeof *dev->qp_table,
+	get_random_bytes(&dev->qp_rnd, sizeof(dev->qp_rnd));
+	dev->qp_table = kmalloc(dev->qp_table_size * sizeof *dev->qp_table,
 				GFP_KERNEL);
 	if (!dev->qp_table) {
 		ret = -ENOMEM;
 		goto err_qpt;
 	}
+	for (i = 0; i < dev->qp_table_size; i++)
+		RCU_INIT_POINTER(dev->qp_table[i], NULL);
 
 	for (i = 0; i < dd->num_pports; i++)
 		init_ibport(ppd + i);
diff --git a/drivers/infiniband/hw/qib/qib_verbs.h b/drivers/infiniband/hw/qib/qib_verbs.h
index ec3711f..d7b6109 100644
--- a/drivers/infiniband/hw/qib/qib_verbs.h
+++ b/drivers/infiniband/hw/qib/qib_verbs.h
@@ -724,7 +724,8 @@ struct qib_ibdev {
 	dma_addr_t pio_hdrs_phys;
 	/* list of QPs waiting for RNR timer */
 	spinlock_t pending_lock; /* protect wait lists, PMA counters, etc. */
-	unsigned qp_table_size; /* size of the hash table */
+	u32 qp_table_size; /* size of the hash table */
+	u32 qp_rnd; /* random bytes for hash */
 	spinlock_t qpt_lock;
 
 	u32 n_piowait;