[CIFS] Add null malloc response check in notify experimental code

Signed-off-by: Steve French (sfrench@us.ibm.com)
diff --git a/fs/cifs/cifs_debug.c b/fs/cifs/cifs_debug.c
index f4054d6..22a444a 100644
--- a/fs/cifs/cifs_debug.c
+++ b/fs/cifs/cifs_debug.c
@@ -217,7 +217,7 @@
         if (rc)
                 return rc;
 
-        if (c == '1' || c == 'y' || c == 'Y') {
+        if (c == '1' || c == 'y' || c == 'Y' || c == '0') {
 		read_lock(&GlobalSMBSeslock);
 		list_for_each(tmp, &GlobalTreeConnectionList) {
 			tcon = list_entry(tmp, struct cifsTconInfo,