[PATCH 4.9 50/72] staging: greybus: add host device function pointer checks

[Greg Kroah-Hartman]

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jason Hrycay <jhrycay@xxxxxxxxx>


[ Upstream commit f05a88a39c5b5f226e08e626998bb920723b7d85 ]

Add sanity checks for cport_quiesce and cport_clear before invoking the
callbacks as these function pointers are not required during the host
device registration. This follows the logic implemented elsewhere for
various other function pointers.

Signed-off-by: Jason Hrycay <jhrycay@xxxxxxxxx>
Reviewed-by: Bryan O'Donoghue <pure.logic@xxxxxxxxxxxxxxxxx>
Acked-by: Johan Hovold <johan@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/staging/greybus/connection.c |    6 ++++++
 1 file changed, 6 insertions(+)

--- a/drivers/staging/greybus/connection.c
+++ b/drivers/staging/greybus/connection.c
@@ -357,6 +357,9 @@ static int gb_connection_hd_cport_quiesc
 	size_t peer_space;
 	int ret;
 
+	if (!hd->driver->cport_quiesce)
+		return 0;
+
 	peer_space = sizeof(struct gb_operation_msg_hdr) +
 			sizeof(struct gb_cport_shutdown_request);
 
@@ -380,6 +383,9 @@ static int gb_connection_hd_cport_clear(
 	struct gb_host_device *hd = connection->hd;
 	int ret;
 
+	if (!hd->driver->cport_clear)
+		return 0;
+
 	ret = hd->driver->cport_clear(hd, connection->hd_cport_id);
 	if (ret) {
 		dev_err(&hd->dev, "%s: failed to clear host cport: %d\n",