Mismerge datafilt.c
OS-4213 lxbrand should be able to set TCP_DEFER_ACCEPT after other socket operations

@@ -83,12 +83,17 @@
 int
 _init(void)
 {
         int error;
 
-        if ((error = sof_register(SOF_VERSION, DATAFILT_MODULE, &dataf_ops, 0))
-            != 0)
+        /*
+         * This module is safe to attach even after some preliminary socket
+         * setup calls have taken place. See the comment for SOF_ATT_SAFE.
+         */
+        error = sof_register(SOF_VERSION, DATAFILT_MODULE, &dataf_ops,
+            SOF_ATT_SAFE);
+        if (error != 0)
                 return (error);
         if ((error = mod_install(&dataf_modlinkage)) != 0)
                 (void) sof_unregister(DATAFILT_MODULE);
 
         return (error);