// FIXME: current not recognized as task_struct*, fixhack with regexp
identifier current =~ "^current$";

Would you really like to use a regular expression for finding a single word?

identifier state_var;
position pos;
@@

(
  p->state & state_var@pos
|
  current->state & state_var@pos
|

I see further opportunities to make such a SmPL disjunction more succinct.

*
( ( \( p \| current \) ) -> state & state_var@pos
|
…

* How do you think about to work with a SmPL constraint
  for a metavariable with the type “binary operator”?

  set_current_state(state_var@pos)
|
  set_special_state(state_var@pos)

| \( set_current_state \| set_special_state \) (state_var@pos)

|
  signal_pending_state(state_var@pos, p)
|
  signal_pending_state(state_var@pos, current)

| signal_pending_state(state_var@pos, \( p \| current \) )


Regards,
Markus