xref: /linux/scripts/coccinelle/locks/double_lock.cocci (revision ca55b2fef3a9373fcfc30f82fd26bc7fccbda732) 
1/// Find double locks.  False positives may occur when some paths cannot
2/// occur at execution, due to the values of variables, and when there is
3/// an intervening function call that releases the lock.
4///
5// Confidence: Moderate
6// Copyright: (C) 2010 Nicolas Palix, DIKU.  GPLv2.
7// Copyright: (C) 2010 Julia Lawall, DIKU.  GPLv2.
8// Copyright: (C) 2010 Gilles Muller, INRIA/LiP6.  GPLv2.
9// URL: http://coccinelle.lip6.fr/
10// Comments:
11// Options: --no-includes --include-headers
12
13virtual org
14virtual report
15
16@locked@
17position p1;
18expression E1;
19position p;
20@@
21
22(
23mutex_lock@p1
24|
25mutex_trylock@p1
26|
27spin_lock@p1
28|
29spin_trylock@p1
30|
31read_lock@p1
32|
33read_trylock@p1
34|
35write_lock@p1
36|
37write_trylock@p1
38) (E1@p,...);
39
40@balanced@
41position p1 != locked.p1;
42position locked.p;
43identifier lock,unlock;
44expression x <= locked.E1;
45expression E,locked.E1;
46expression E2;
47@@
48
49if (E) {
50 <+... when != E1
51 lock(E1@p,...)
52 ...+>
53}
54... when != E1
55    when != \(x = E2\|&x\)
56    when forall
57if (E) {
58 <+... when != E1
59 unlock@p1(E1,...)
60 ...+>
61}
62
63@r depends on !balanced exists@
64expression x <= locked.E1;
65expression locked.E1;
66expression E2;
67identifier lock;
68position locked.p,p1,p2;
69@@
70
71lock@p1 (E1@p,...);
72... when != E1
73    when != \(x = E2\|&x\)
74lock@p2 (E1,...);
75
76@script:python depends on org@
77p1 << r.p1;
78p2 << r.p2;
79lock << r.lock;
80@@
81
82cocci.print_main(lock,p1)
83cocci.print_secs("second lock",p2)
84
85@script:python depends on report@
86p1 << r.p1;
87p2 << r.p2;
88lock << r.lock;
89@@
90
91msg = "second lock on line %s" % (p2[0].line)
92coccilib.report.print_report(p1[0],msg)
93