/// Find missing unlocks.  This semantic match considers the specific case
  /// where the unlock is missing from an if branch, and there is a lock
  /// before the if and an unlock after the if.  False positives are due to
  /// cases where the if branch represents a case where the function is
  /// supposed to exit with the lock held, or where there is some preceding
  /// function call that releases the lock.
  ///
  // Confidence: Moderate

  // Copyright: (C) 2010-2012 Nicolas Palix.  GPLv2.
  // Copyright: (C) 2010-2012 Julia Lawall, INRIA/LIP6.  GPLv2.
  // Copyright: (C) 2010-2012 Gilles Muller, INRIA/LiP6.  GPLv2.

  // URL: http://coccinelle.lip6.fr/
  // Comments:
  // Options: -no_includes -include_headers

  virtual context

  virtual org
  virtual report
  
  @prelocked@
  position p1,p;
  expression E1;
  @@
  
  (
  mutex_lock@p1
  |
  mutex_trylock@p1
  |
  spin_lock@p1
  |
  spin_trylock@p1
  |
  read_lock@p1
  |
  read_trylock@p1
  |
  write_lock@p1
  |
  write_trylock@p1
  |
  read_lock_irq@p1
  |
  write_lock_irq@p1
  |
  read_lock_irqsave@p1
  |
  write_lock_irqsave@p1
  |
  spin_lock_irq@p1
  |
  spin_lock_irqsave@p1
  ) (E1@p,...);
  
  @looped@
  position r;
  @@
  
  for(...;...;...) { <+... return@r ...; ...+> }

  @err exists@

  expression E1;
  position prelocked.p;
  position up != prelocked.p1;
  position r!=looped.r;
  identifier lock,unlock;
  @@

  *lock(E1@p,...);

  <+... when != E1
  if (...) {
    ... when != E1

  *  return@r ...;

  }
  ...+>

  *unlock@up(E1,...);

  
  @script:python depends on org@
  p << prelocked.p1;
  lock << err.lock;
  unlock << err.unlock;
  p2 << err.r;
  @@
  
  cocci.print_main(lock,p)
  cocci.print_secs(unlock,p2)
  
  @script:python depends on report@
  p << prelocked.p1;
  lock << err.lock;
  unlock << err.unlock;
  p2 << err.r;
  @@
  
  msg = "preceding lock on line %s" % (p[0].line)
  coccilib.report.print_report(p2[0],msg)