Coccinelle: Add locks/double_lock.cocci

/// Find double locks.  False positives may occur when some paths cannot

/// occur at execution, due to the values of variables, and when there is

/// an intervening function call that releases the lock.

///

// Confidence: Moderate

// Copyright: (C) 2010 Nicolas Palix, DIKU.  GPLv2.

// Copyright: (C) 2010 Julia Lawall, DIKU.  GPLv2.

// Copyright: (C) 2010 Gilles Muller, INRIA/LiP6.  GPLv2.

// URL: http://coccinelle.lip6.fr/

// Comments:

// Options: -no_includes -include_headers

virtual org

virtual report

@locked@

position p1;

expression E1;

position p;

@@

(

mutex_lock@p1

|

mutex_trylock@p1

|

spin_lock@p1

|

spin_trylock@p1

|

read_lock@p1

|

read_trylock@p1

|

write_lock@p1

|

write_trylock@p1

) (E1@p,...);

@balanced@

position p1 != locked.p1;

position locked.p;

identifier lock,unlock;

expression x <= locked.E1;

expression E,locked.E1;

expression E2;

@@

if (E) {

 <+... when != E1

 lock(E1@p,...)

 ...+>

}

... when != E1

    when != \(x = E2\|&x\)

    when forall

if (E) {

 <+... when != E1

 unlock@p1(E1,...)

 ...+>

}

@r depends on !balanced exists@

expression x <= locked.E1;

expression locked.E1;

expression E2;

identifier lock;

position locked.p,p1,p2;

@@

lock@p1 (E1@p,...);

... when != E1

    when != \(x = E2\|&x\)

lock@p2 (E1,...);

@script:python depends on org@

p1 << r.p1;

p2 << r.p2;

lock << r.lock;

@@

cocci.print_main(lock,p1)

cocci.print_secs("second lock",p2)

@script:python depends on report@

p1 << r.p1;

p2 << r.p2;

lock << r.lock;

@@

msg = "second lock on line %s" % (p2[0].line)

coccilib.report.print_report(p1[0],msg)