misc: mic: Add support for kernel mode SCIF clients

Add support for registration/de-registration of kernel mode SCIF
clients. SCIF clients are probed with new and existing SCIF peer
devices. Similarly the client remove method is called when SCIF
peer devices are removed.

Changes to SCIF peer device framework necessitated by supporting
kernel mode SCIF clients are also included in this patch.

Reviewed-by: Nikhil Rao <nikhil.rao@intel.com>
Reviewed-by: Sudeep Dutt <sudeep.dutt@intel.com>
Signed-off-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/misc/mic/scif/scif_nodeqp.c b/drivers/misc/mic/scif/scif_nodeqp.c
index 6dfdae3..5cdb9f0 100644
--- a/drivers/misc/mic/scif/scif_nodeqp.c
+++ b/drivers/misc/mic/scif/scif_nodeqp.c
@@ -260,6 +260,11 @@
 		     r_buf,
 		     get_count_order(remote_size));
 	/*
+	 * Because the node QP may already be processing an INIT message, set
+	 * the read pointer so the cached read offset isn't lost
+	 */
+	qp->remote_qp->local_read = qp->inbound_q.current_read_offset;
+	/*
 	 * resetup the inbound_q now that we know where the
 	 * inbound_read really is.
 	 */
@@ -529,27 +534,6 @@
 	}
 }
 
-void scif_qp_response_ack(struct work_struct *work)
-{
-	struct scif_dev *scifdev = container_of(work, struct scif_dev,
-						init_msg_work);
-	struct scif_peer_dev *spdev;
-
-	/* Drop the INIT message if it has already been received */
-	if (_scifdev_alive(scifdev))
-		return;
-
-	spdev = scif_peer_register_device(scifdev);
-	if (IS_ERR(spdev))
-		return;
-
-	if (scif_is_mgmt_node()) {
-		mutex_lock(&scif_info.conflock);
-		scif_p2p_setup();
-		mutex_unlock(&scif_info.conflock);
-	}
-}
-
 static char *message_types[] = {"BAD",
 				"INIT",
 				"EXIT",
@@ -682,13 +666,14 @@
 	 * address to complete initializing the inbound_q.
 	 */
 	flush_delayed_work(&scifdev->qp_dwork);
-	/*
-	 * Delegate the peer device registration to a workqueue, otherwise if
-	 * SCIF client probe (called during peer device registration) calls
-	 * scif_connect(..), it will block the message processing thread causing
-	 * a deadlock.
-	 */
-	schedule_work(&scifdev->init_msg_work);
+
+	scif_peer_register_device(scifdev);
+
+	if (scif_is_mgmt_node()) {
+		mutex_lock(&scif_info.conflock);
+		scif_p2p_setup();
+		mutex_unlock(&scif_info.conflock);
+	}
 }
 
 /**
@@ -838,13 +823,13 @@
 				      msecs_to_jiffies(SCIF_NODE_QP_TIMEOUT));
 		return;
 	}
-	scif_peer_register_device(peerdev);
 	return;
 timeout:
 	dev_err(&peerdev->sdev->dev,
 		"%s %d remote node %d offline,  state = 0x%x\n",
 		__func__, __LINE__, peerdev->node, qp->qp_state);
 	qp->remote_qp->qp_state = SCIF_QP_OFFLINE;
+	scif_peer_unregister_device(peerdev);
 	scif_cleanup_scifdev(peerdev);
 }
 
@@ -894,6 +879,9 @@
 		goto local_error;
 	peerdev->rdb = msg->payload[2];
 	qp->remote_qp->qp_state = SCIF_QP_ONLINE;
+
+	scif_peer_register_device(peerdev);
+
 	schedule_delayed_work(&peerdev->p2p_dwork, 0);
 	return;
 local_error:
@@ -1169,7 +1157,6 @@
 	int err = 0;
 	void *local_q;
 	struct scif_qp *qp;
-	struct scif_peer_dev *spdev;
 
 	err = scif_setup_intr_wq(scifdev);
 	if (err)
@@ -1216,15 +1203,11 @@
 		     &qp->local_write,
 		     local_q, get_count_order(SCIF_NODE_QP_SIZE));
 	scif_info.nodeid = scifdev->node;
-	spdev = scif_peer_register_device(scifdev);
-	if (IS_ERR(spdev)) {
-		err = PTR_ERR(spdev);
-		goto free_local_q;
-	}
+
+	scif_peer_register_device(scifdev);
+
 	scif_info.loopb_dev = scifdev;
 	return err;
-free_local_q:
-	kfree(local_q);
 free_qpairs:
 	kfree(scifdev->qpairs);
 destroy_loopb_wq:
@@ -1243,13 +1226,7 @@
  */
 int scif_destroy_loopback_qp(struct scif_dev *scifdev)
 {
-	struct scif_peer_dev *spdev;
-
-	rcu_read_lock();
-	spdev = rcu_dereference(scifdev->spdev);
-	rcu_read_unlock();
-	if (spdev)
-		scif_peer_unregister_device(spdev);
+	scif_peer_unregister_device(scifdev);
 	destroy_workqueue(scif_info.loopb_wq);
 	scif_destroy_intr_wq(scifdev);
 	kfree(scifdev->qpairs->outbound_q.rb_base);