IB/ipath: Wait for PIO available interrupt

The send function is called when posting new send work requests.
There is no point in trying to send a packet if the QP is already
waiting for a HW send buffer so don't clear the busy bit until the
buffer available interrupt happens.
Signed-off-by: Ralph Campbell <ralph.campbell@qlogic.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

drivers/infiniband/hw/ipath/ipath_ruc.c

@@ -503,11 +503,9 @@ void ipath_no_bufs_available(struct ipath_qp *qp, struct ipath_ibdev *dev)
 	 * could be called.  If we are still in the tasklet function,
 	 * tasklet_hi_schedule() will not call us until the next time
 	 * tasklet_hi_schedule() is called.
-	 * We clear the tasklet flag now since we are committing to return
-	 * from the tasklet function.
+	 * We leave the busy flag set so that another post send doesn't
+	 * try to put the same QP on the piowait list again.
 	 */
-	clear_bit(IPATH_S_BUSY, &qp->s_busy);
-	tasklet_unlock(&qp->s_task);
 	want_buffer(dev->dd);
 	dev->n_piowait++;
 }

drivers/infiniband/hw/ipath/ipath_verbs.c

@@ -948,6 +948,7 @@ int ipath_ib_piobufavail(struct ipath_ibdev *dev)
 		qp = list_entry(dev->piowait.next, struct ipath_qp,
 				piowait);
 		list_del_init(&qp->piowait);
+		clear_bit(IPATH_S_BUSY, &qp->s_busy);
 		tasklet_hi_schedule(&qp->s_task);
 	}
 	spin_unlock_irqrestore(&dev->pending_lock, flags);