When we close a channel, we set the corresponding callback function to NULL.
Check before invoking the channel callback.
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
         */
        channel = relid2channel(relid);
 
-       if (channel) {
+       if (channel && (channel->onchannel_callback != NULL)) {
                channel->onchannel_callback(channel->channel_callback_context);
        } else {
                pr_err("channel not found for relid - %u\n", relid);