From cb050f2c3011b25dbad5090a147a7417eee44f8d Mon Sep 17 00:00:00 2001
From: nirenjan <nirenjan@gmail.com>
Date: Sat, 18 Apr 2020 01:28:12 -0700
Subject: [PATCH] Allow NULL cb_handle in libx52_hotplug_register_callback

This allows the caller to register a callback and forget about it. This
is useful in cases where a particular callback needs to be run
everytime, and there is no point in deregistering it until the
application terminates, at which point `libx52_hotplug_exit` will take
care of the cleanup.
---
 lib/libx52/x52_core.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/lib/libx52/x52_core.c b/lib/libx52/x52_core.c
index 7560c8c..be42d8e 100644
--- a/lib/libx52/x52_core.c
+++ b/lib/libx52/x52_core.c
@@ -328,7 +328,10 @@ int libx52_hotplug_register_callback(libx52_hotplug_service *svc,
     /* Insert the node into the callbacks list */
     svc->callbacks[i] = hdl;
 
-    *cb_handle = hdl;
+    if (cb_handle != NULL) {
+        *cb_handle = hdl;
+    }
+
     return LIBX52_SUCCESS;
 }