RDS: Replace queue_work() by cond_resched() in the tasklet to breakup RX stream

Orabug: 18801931

Signed-off-by: Bang Nguyen <[email protected]>
Signed-off-by: Ajaykumar Hotchandani <[email protected]>
(cherry picked from commit 74723dd3283d1bf2b352e5f71fe27340283716ed)
Signed-off-by: Jerry Snitselaar <[email protected]>

Author: Bang Nguyen

net/rds/ib.h

@@ -235,9 +235,6 @@ struct rds_ib_connection {
 	int			i_scq_vector;
 	int			i_rcq_vector;
 
-	spinlock_t		i_rx_lock;
-	struct rds_ib_rx_work	i_rx_w;
-	unsigned int		i_rx_wait_for_handler;
 	unsigned int            i_rx_poll_cq;
 };
 

net/rds/ib_cm.c

@@ -329,18 +329,11 @@ static void poll_cq(struct rds_ib_connection *ic, struct ib_cq *cq,
 
 	while ((nr = ib_poll_cq(cq, RDS_WC_MAX, wcs)) > 0) {
 		for (i = 0; i < nr; i++) {
-			if (rx) {
-				if ((++ic->i_rx_poll_cq % RDS_IB_RX_LIMIT)
-				    == 0) {
-					rdsdebug("connection "
-						 "<%u.%u.%u.%u,%u.%u.%u.%u,%d> "
-						 "RX poll_cq processed %d\n",
-						 NIPQUAD(ic->conn->c_laddr),
-						 NIPQUAD(ic->conn->c_faddr),
-						 ic->conn->c_tos,
-						 ic->i_rx_poll_cq);
-				}
-			}
+
+			if (rx &&
+				(++ic->i_rx_poll_cq % RDS_IB_RX_LIMIT) == 0)
+					cond_resched();
+
 			wc = wcs + i;
 			rdsdebug("wc wr_id 0x%llx status %u byte_len %u imm_data %u\n",
 				 (unsigned long long)wc->wr_id, wc->status, wc->byte_len,
@@ -351,10 +344,6 @@ static void poll_cq(struct rds_ib_connection *ic, struct ib_cq *cq,
 			else
 				rds_ib_recv_cqe_handler(ic, wc, ack_state);
 		}
-
-		if (rx && ic->i_rx_poll_cq >= RDS_IB_RX_LIMIT)
-			break;
-
 	}
 }
 
@@ -381,14 +370,9 @@ void rds_ib_tasklet_fn_send(unsigned long data)
 		rds_send_xmit(ic->conn);
 }
 
-/*
- * Note: rds_ib_rx(): don't call with irqs disabled.
- * It calls rds_send_drop_acked() which calls other
- * routines that reach into rds_rdma_free_op()
- * where irqs_disabled() warning is asserted!
- */
-static void rds_ib_rx(struct rds_ib_connection *ic)
+void rds_ib_tasklet_fn_recv(unsigned long data)
 {
+	struct rds_ib_connection *ic = (struct rds_ib_connection *) data;
 	struct rds_connection *conn = ic->conn;
 	struct rds_ib_ack_state ack_state;
 	struct rds_ib_device *rds_ibdev = ic->rds_ibdev;
@@ -406,53 +390,22 @@ static void rds_ib_rx(struct rds_ib_connection *ic)
 
 	if (ack_state.ack_next_valid)
 		rds_ib_set_ack(ic, ack_state.ack_next, ack_state.ack_required);
+
 	if (ack_state.ack_recv_valid && ack_state.ack_recv > ic->i_ack_recv) {
 		rds_send_drop_acked(conn, ack_state.ack_recv, NULL);
 		ic->i_ack_recv = ack_state.ack_recv;
 	}
+
 	if (rds_conn_up(conn))
 		rds_ib_attempt_ack(ic);
 
 	if (rds_ib_srq_enabled)
 		if ((atomic_read(&rds_ibdev->srq->s_num_posted) <
-					rds_ib_srq_hwm_refill) &&
-			!test_and_set_bit(0, &rds_ibdev->srq->s_refill_gate))
-				queue_delayed_work(rds_wq,
-					&rds_ibdev->srq->s_refill_w, 0);
-
-	if (ic->i_rx_poll_cq >= RDS_IB_RX_LIMIT) {
-		ic->i_rx_w.ic = ic;
-		queue_delayed_work(rds_aux_wq, &ic->i_rx_w.dlywork,
-					msecs_to_jiffies(10));
-		ic->i_rx_wait_for_handler = 1;
-	}
+				rds_ib_srq_hwm_refill) &&
+				!test_and_set_bit(0, &rds_ibdev->srq->s_refill_gate))
+			queue_delayed_work(rds_wq, &rds_ibdev->srq->s_refill_w, 0);
 }
 
-void rds_ib_tasklet_fn_recv(unsigned long data)
-{
-	struct rds_ib_connection *ic = (struct rds_ib_connection *) data;
-
-	spin_lock(&ic->i_rx_lock);
-	if (ic->i_rx_wait_for_handler)
-		goto out;
-	rds_ib_rx(ic);
-out:
-	spin_unlock(&ic->i_rx_lock);
-}
-
-static void rds_ib_rx_handler(struct work_struct *workarg)
-{
-	struct delayed_work *delayedwork =
-		container_of(workarg, struct delayed_work, work);
-	struct rds_ib_rx_work *rirwork =
-		container_of(delayedwork, struct rds_ib_rx_work, dlywork);
-	struct rds_ib_connection *ic = rirwork->ic;
-
-	spin_lock(&ic->i_rx_lock);
-	ic->i_rx_wait_for_handler = 0;
-	rds_ib_rx(ic);
-	spin_unlock(&ic->i_rx_lock);
-}
 
 static void rds_ib_qp_event_handler(struct ib_event *event, void *data)
 {
@@ -1111,17 +1064,9 @@ void rds_ib_conn_shutdown(struct rds_connection *conn)
 		}
 
 		/* quiesce tx and rx completion before tearing down */
-		while (!wait_event_timeout(rds_ib_ring_empty_wait,
-				rds_ib_ring_empty(&ic->i_recv_ring) &&
-				(atomic_read(&ic->i_signaled_sends) == 0),
-				msecs_to_jiffies(5000))) {
-
-			if (!rds_ib_ring_empty(&ic->i_recv_ring)) {
-				spin_lock(&ic->i_rx_lock);
-				rds_ib_rx(ic);
-				spin_unlock(&ic->i_rx_lock);
-			}
-		}
+		wait_event(rds_ib_ring_empty_wait,
+			rds_ib_ring_empty(&ic->i_recv_ring) &&
+			(atomic_read(&ic->i_signaled_sends) == 0));
 
 		tasklet_kill(&ic->i_stasklet);
 		tasklet_kill(&ic->i_rtasklet);
@@ -1254,7 +1199,6 @@ int rds_ib_conn_alloc(struct rds_connection *conn, gfp_t gfp)
 	spin_lock_init(&ic->i_ack_lock);
 #endif
 	atomic_set(&ic->i_signaled_sends, 0);
-	spin_lock_init(&ic->i_rx_lock);
 
 	/*
 	 * rds_ib_conn_shutdown() waits for these to be emptied so they
@@ -1269,7 +1213,6 @@ int rds_ib_conn_alloc(struct rds_connection *conn, gfp_t gfp)
 	init_completion(&ic->i_last_wqe_complete);
 
 	INIT_DELAYED_WORK(&ic->i_migrate_w.work, rds_ib_migrate);
-	INIT_DELAYED_WORK(&ic->i_rx_w.dlywork, rds_ib_rx_handler);
 
 	spin_lock_irqsave(&ib_nodev_conns_lock, flags);
 	list_add_tail(&ic->ib_node, &ib_nodev_conns);