IB/hfi1: Reduce lock contention on iowait_lock for sdma and pio

Commit 4e045572e2c2 ("IB/hfi1: Add unique txwait_lock for txreq events")
laid the ground work to support per resource waiting locking.

This patch adds that with a lock unique to each sdma engine and pio
sendcontext and makes necessary changes for verbs, PSM, and vnic to use
the new locks.

This is particularly beneficial for smaller messages that will exhaust
resources at a faster rate.

Fixes: 7724105686e7 ("IB/hfi1: add driver files")
Reviewed-by: Gary Leshner <[e-mail]>
Signed-off-by: Mike Marciniszyn <[e-mail]>
Signed-off-by: Dennis Dalessandro <[e-mail]>
Signed-off-by: Jason Gunthorpe <[e-mail]>

drivers/infiniband/hw/hfi1/pio.c

···
 	spin_lock_init(&sc->alloc_lock);
 	spin_lock_init(&sc->release_lock);
 	spin_lock_init(&sc->credit_ctrl_lock);
+	seqlock_init(&sc->waitlock);
 	INIT_LIST_HEAD(&sc->piowait);
 	INIT_WORK(&sc->halt_work, sc_halted);
 	init_waitqueue_head(&sc->halt_wait);
···
 static void sc_piobufavail(struct send_context *sc)
 {
 	struct hfi1_devdata *dd = sc->dd;
-	struct hfi1_ibdev *dev = &dd->verbs_dev;
 	struct list_head *list;
 	struct rvt_qp *qps[PIO_WAIT_BATCH_SIZE];
 	struct rvt_qp *qp;
···
 	 * could end up with QPs on the wait list with the interrupt
 	 * disabled.
 	 */
-	write_seqlock_irqsave(&dev->iowait_lock, flags);
+	write_seqlock_irqsave(&sc->waitlock, flags);
 	while (!list_empty(list)) {
 		struct iowait *wait;
 
···
 		if (!list_empty(list))
 			hfi1_sc_wantpiobuf_intr(sc, 1);
 	}
-	write_sequnlock_irqrestore(&dev->iowait_lock, flags);
+	write_sequnlock_irqrestore(&sc->waitlock, flags);
 
 	/* Wake up the most starved one first */
 	if (n)

drivers/infiniband/hw/hfi1/pio.h

···
 	volatile __le64 *hw_free;	/* HW free counter */
 	/* list for PIO waiters */
 	struct list_head piowait  ____cacheline_aligned_in_smp;
+	seqlock_t waitlock;
+
 	spinlock_t credit_ctrl_lock ____cacheline_aligned_in_smp;
 	u32 credit_intr_count;		/* count of credit intr users */
 	u64 credit_ctrl;		/* cache for credit control */

drivers/infiniband/hw/hfi1/qp.c

···
 
 static void qp_pio_drain(struct rvt_qp *qp)
 {
-	struct hfi1_ibdev *dev;
 	struct hfi1_qp_priv *priv = qp->priv;
 
 	if (!priv->s_sendcontext)
 		return;
-	dev = to_idev(qp->ibqp.device);
 	while (iowait_pio_pending(&priv->s_iowait)) {
-		write_seqlock_irq(&dev->iowait_lock);
+		write_seqlock_irq(&priv->s_sendcontext->waitlock);
 		hfi1_sc_wantpiobuf_intr(priv->s_sendcontext, 1);
-		write_sequnlock_irq(&dev->iowait_lock);
+		write_sequnlock_irq(&priv->s_sendcontext->waitlock);
 		iowait_pio_drain(&priv->s_iowait);
-		write_seqlock_irq(&dev->iowait_lock);
+		write_seqlock_irq(&priv->s_sendcontext->waitlock);
 		hfi1_sc_wantpiobuf_intr(priv->s_sendcontext, 0);
-		write_sequnlock_irq(&dev->iowait_lock);
+		write_sequnlock_irq(&priv->s_sendcontext->waitlock);
 	}
 }
 
···
 	struct hfi1_qp_priv *priv;
 	unsigned long flags;
 	int ret = 0;
-	struct hfi1_ibdev *dev;
 
 	qp = tx->qp;
 	priv = qp->priv;
···
 		 * buffer and undoing the side effects of the copy.
 		 */
 		/* Make a common routine? */
-		dev = &sde->dd->verbs_dev;
 		list_add_tail(&stx->list, &wait->tx_head);
-		write_seqlock(&dev->iowait_lock);
+		write_seqlock(&sde->waitlock);
 		if (sdma_progress(sde, seq, stx))
 			goto eagain;
 		if (list_empty(&priv->s_iowait.list)) {
···
 			qp->s_flags |= RVT_S_WAIT_DMA_DESC;
 			iowait_queue(pkts_sent, &priv->s_iowait,
 				     &sde->dmawait);
-			priv->s_iowait.lock = &dev->iowait_lock;
+			priv->s_iowait.lock = &sde->waitlock;
 			trace_hfi1_qpsleep(qp, RVT_S_WAIT_DMA_DESC);
 			rvt_get_qp(qp);
 		}
-		write_sequnlock(&dev->iowait_lock);
+		write_sequnlock(&sde->waitlock);
 		hfi1_qp_unbusy(qp, wait);
 		spin_unlock_irqrestore(&qp->s_lock, flags);
 		ret = -EBUSY;
···
 	}
 	return ret;
 eagain:
-	write_sequnlock(&dev->iowait_lock);
+	write_sequnlock(&sde->waitlock);
 	spin_unlock_irqrestore(&qp->s_lock, flags);
 	list_del_init(&stx->list);
 	return -EAGAIN;

drivers/infiniband/hw/hfi1/sdma.c

···
 		seqlock_init(&sde->head_lock);
 		spin_lock_init(&sde->senddmactrl_lock);
 		spin_lock_init(&sde->flushlist_lock);
+		seqlock_init(&sde->waitlock);
 		/* insure there is always a zero bit */
 		sde->ahg_bits = 0xfffffffe00000000ULL;
 
···
 	struct iowait *wait, *nw;
 	struct iowait *waits[SDMA_WAIT_BATCH_SIZE];
 	uint i, n = 0, seq, max_idx = 0;
-	struct hfi1_ibdev *dev = &sde->dd->verbs_dev;
 	u8 max_starved_cnt = 0;
 
 #ifdef CONFIG_SDMA_VERBOSITY
···
 #endif
 
 	do {
-		seq = read_seqbegin(&dev->iowait_lock);
+		seq = read_seqbegin(&sde->waitlock);
 		if (!list_empty(&sde->dmawait)) {
 			/* at least one item */
-			write_seqlock(&dev->iowait_lock);
+			write_seqlock(&sde->waitlock);
 			/* Harvest waiters wanting DMA descriptors */
 			list_for_each_entry_safe(
 					wait,
···
 				list_del_init(&wait->list);
 				waits[n++] = wait;
 			}
-			write_sequnlock(&dev->iowait_lock);
+			write_sequnlock(&sde->waitlock);
 			break;
 		}
-	} while (read_seqretry(&dev->iowait_lock, seq));
+	} while (read_seqretry(&sde->waitlock, seq));
 
 	/* Schedule the most starved one first */
 	if (n)

drivers/infiniband/hw/hfi1/sdma.h

···
 	u64                     progress_int_cnt;
 
 	/* private: */
+	seqlock_t            waitlock;
 	struct list_head      dmawait;
 
 	/* CONFIG SDMA for now, just blindly duplicate */

drivers/infiniband/hw/hfi1/user_sdma.c

···
 {
 	struct hfi1_user_sdma_pkt_q *pq =
 		container_of(wait->iow, struct hfi1_user_sdma_pkt_q, busy);
-	struct hfi1_ibdev *dev = &pq->dd->verbs_dev;
 	struct user_sdma_txreq *tx =
 		container_of(txreq, struct user_sdma_txreq, txreq);
 
···
 	 * it is supposed to be enqueued.
 	 */
 	xchg(&pq->state, SDMA_PKT_Q_DEFERRED);
-	write_seqlock(&dev->iowait_lock);
+	write_seqlock(&sde->waitlock);
 	if (list_empty(&pq->busy.list))
 		iowait_queue(pkts_sent, &pq->busy, &sde->dmawait);
-	write_sequnlock(&dev->iowait_lock);
+	write_sequnlock(&sde->waitlock);
 	return -EBUSY;
 eagain:
 	return -EAGAIN;

drivers/infiniband/hw/hfi1/verbs.c

···
 {
 	struct hfi1_qp_priv *priv = qp->priv;
 	struct hfi1_devdata *dd = sc->dd;
-	struct hfi1_ibdev *dev = &dd->verbs_dev;
 	unsigned long flags;
 	int ret = 0;
 
···
 	 */
 	spin_lock_irqsave(&qp->s_lock, flags);
 	if (ib_rvt_state_ops[qp->state] & RVT_PROCESS_RECV_OK) {
-		write_seqlock(&dev->iowait_lock);
+		write_seqlock(&sc->waitlock);
 		list_add_tail(&ps->s_txreq->txreq.list,
 			      &ps->wait->tx_head);
 		if (list_empty(&priv->s_iowait.list)) {
···
 			was_empty = list_empty(&sc->piowait);
 			iowait_queue(ps->pkts_sent, &priv->s_iowait,
 				     &sc->piowait);
-			priv->s_iowait.lock = &dev->iowait_lock;
+			priv->s_iowait.lock = &sc->waitlock;
 			trace_hfi1_qpsleep(qp, RVT_S_WAIT_PIO);
 			rvt_get_qp(qp);
 			/* counting: only call wantpiobuf_intr if first user */
 			if (was_empty)
 				hfi1_sc_wantpiobuf_intr(sc, 1);
 		}
-		write_sequnlock(&dev->iowait_lock);
+		write_sequnlock(&sc->waitlock);
 		hfi1_qp_unbusy(qp, ps->wait);
 		ret = -EBUSY;
 	}

drivers/infiniband/hw/hfi1/vnic_sdma.c

···
 {
 	struct hfi1_vnic_sdma *vnic_sdma =
 		container_of(wait->iow, struct hfi1_vnic_sdma, wait);
-	struct hfi1_ibdev *dev = &vnic_sdma->dd->verbs_dev;
 
-	write_seqlock(&dev->iowait_lock);
+	write_seqlock(&sde->waitlock);
 	if (sdma_progress(sde, seq, txreq)) {
-		write_sequnlock(&dev->iowait_lock);
+		write_sequnlock(&sde->waitlock);
 		return -EAGAIN;
 	}
 
 	vnic_sdma->state = HFI1_VNIC_SDMA_Q_DEFERRED;
 	if (list_empty(&vnic_sdma->wait.list))
 		iowait_queue(pkts_sent, wait->iow, &sde->dmawait);
-	write_sequnlock(&dev->iowait_lock);
+	write_sequnlock(&sde->waitlock);
 	return -EBUSY;
 }