From 724b619dfbe1238eb8b9bd4916eeaf40b5640b28 Mon Sep 17 00:00:00 2001
From: Greg Kroah-Hartman <greg@kroah.com>
Date: Mon, 27 Oct 2014 13:32:27 +0800
Subject: [PATCH] greybus: core: check for valid hcd callbacks

When registering a host controller, verify that all of the needed
callbacks are present, so we don't have to do the testing on any "hot"
paths when we want to send real data.

Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>
Reviewed-by: Alex Elder <elder@linaro.org.
---
 drivers/staging/greybus/core.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/drivers/staging/greybus/core.c b/drivers/staging/greybus/core.c
index 853bfd6503f6..1436b3d9427d 100644
--- a/drivers/staging/greybus/core.c
+++ b/drivers/staging/greybus/core.c
@@ -208,6 +208,19 @@ struct greybus_host_device *greybus_create_hd(struct greybus_host_driver *driver
 {
 	struct greybus_host_device *hd;
 
+	/*
+	 * Validate that the driver implements all of the callbacks
+	 * so that we don't have to every time we make them.
+	 */
+	if ((!driver->alloc_gbuf_data) ||
+	    (!driver->free_gbuf_data) ||
+	    (!driver->submit_svc) ||
+	    (!driver->submit_gbuf) ||
+	    (!driver->abort_gbuf)) {
+		pr_err("Must implement all greybus_host_driver callbacks!\n");
+		return NULL;
+	}
+
 	hd = kzalloc(sizeof(*hd) + driver->hd_priv_size, GFP_KERNEL);
 	if (!hd)
 		return NULL;
-- 
2.20.1