IB/ipath: Fix RNR NAK handling

This patch fixes a couple of minor problems with RNR NAK handling:
 - The insertion sort was causing extra delay when inserting ahead
   vs. behind an existing entry on the list.
 - A resend of a first packet of a message which is still not ready,
   needs another RNR NAK (i.e., it was suppressed when it shouldn't).
 - Also, the resend tasklet doesn't need to be woken up unless the
   ACK/NAK actually indicates progress has been made.

Signed-off-by: Ralph Campbell <ralph.campbell@qlogic.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

2 files changed, 12 insertions, 12 deletions

diff --git a/drivers/infiniband/hw/ipath/ipath_rc.c b/drivers/infiniband/hw/ipath/ipath_rc.c
index 120a61b03bc4..459e46e2c016 100644
--- a/drivers/infiniband/hw/ipath/ipath_rc.c
+++ b/drivers/infiniband/hw/ipath/ipath_rc.c
@@ -647,6 +647,7 @@ static void send_rc_ack(struct ipath_qp *qp)
 
 queue_ack:
         spin_lock_irqsave(&qp->s_lock, flags);
+        dev->n_rc_qacks++;
         qp->s_flags |= IPATH_S_ACK_PENDING;
         qp->s_nak_state = qp->r_nak_state;
         qp->s_ack_psn = qp->r_ack_psn;
@@ -798,11 +799,13 @@ bail:
 
 static inline void update_last_psn(struct ipath_qp *qp, u32 psn)
 {
-        if (qp->s_wait_credit) {
-                qp->s_wait_credit = 0;
-                tasklet_hi_schedule(&qp->s_task);
+        if (qp->s_last_psn != psn) {
+                qp->s_last_psn = psn;
+                if (qp->s_wait_credit) {
+                        qp->s_wait_credit = 0;
+                        tasklet_hi_schedule(&qp->s_task);
+                }
         }
-        qp->s_last_psn = psn;
 }
 
 /**
@@ -1653,13 +1656,6 @@ void ipath_rc_rcv(struct ipath_ibdev *dev, struct ipath_ib_header *hdr,
         case OP(SEND_FIRST):
                 if (!ipath_get_rwqe(qp, 0)) {
                 rnr_nak:
-                        /*
-                         * A RNR NAK will ACK earlier sends and RDMA writes.
-                         * Don't queue the NAK if a RDMA read or atomic
-                         * is pending though.
-                         */
-                        if (qp->r_nak_state)
-                                goto done;
                         qp->r_nak_state = IB_RNR_NAK | qp->r_min_rnr_timer;
                         qp->r_ack_psn = qp->r_psn;
                         goto send_ack;
diff --git a/drivers/infiniband/hw/ipath/ipath_ruc.c b/drivers/infiniband/hw/ipath/ipath_ruc.c
index 1b4f7e113b21..a59bdbd0ed87 100644
--- a/drivers/infiniband/hw/ipath/ipath_ruc.c
+++ b/drivers/infiniband/hw/ipath/ipath_ruc.c
@@ -98,11 +98,15 @@ void ipath_insert_rnr_queue(struct ipath_qp *qp)
                 while (qp->s_rnr_timeout >= nqp->s_rnr_timeout) {
                         qp->s_rnr_timeout -= nqp->s_rnr_timeout;
                         l = l->next;
-                        if (l->next == &dev->rnrwait)
+                        if (l->next == &dev->rnrwait) {
+                                nqp = NULL;
                                 break;
+                        }
                         nqp = list_entry(l->next, struct ipath_qp,
                                          timerwait);
                 }
+                if (nqp)
+                        nqp->s_rnr_timeout -= qp->s_rnr_timeout;
                 list_add(&qp->timerwait, l);
         }
         spin_unlock_irqrestore(&dev->pending_lock, flags);