1///Find conditions where if and else branch are functionally
 2// identical.
 3//
 4// There can be false positives in cases where the positional
 5// information is used (as with lockdep) or where the identity
 6// is a placeholder for not yet handled cases.
 7// Unfortunately there also seems to be a tendency to use
 8// the last if else/else as a "default behavior" - which some
 9// might consider a legitimate coding pattern. From discussion
10// on kernelnewbies though it seems that this is not really an
11// accepted pattern and if at all it would need to be commented
12//
13// In the Linux kernel it does not seem to actually report
14// false positives except for those that were documented as
15// being intentional.
16// the two known cases are:
17//   arch/sh/kernel/traps_64.c:read_opcode()
18//        } else if ((pc & 1) == 0) {
19//              /* SHcompact */
20//              /* TODO : provide handling for this.  We don't really support
21//                 user-mode SHcompact yet, and for a kernel fault, this would
22//                 have to come from a module built for SHcompact.  */
23//              return -EFAULT;
24//      } else {
25//              /* misaligned */
26//              return -EFAULT;
27//      }
28//   fs/kernfs/file.c:kernfs_fop_open()
29//       * Both paths of the branch look the same.  They're supposed to
30//       * look that way and give @of->mutex different static lockdep keys.
31//       */
32//      if (has_mmap)
33//              mutex_init(&of->mutex);
34//      else
35//              mutex_init(&of->mutex);
36//
37// All other cases look like bugs or at least lack of documentation
38//
39// Confidence: Moderate
40// Copyright: (C) 2016 Nicholas Mc Guire, OSADL.  GPLv2.
41// Comments:
42// Options: --no-includes --include-headers
43
44virtual org
45virtual report
46
47@cond@
48statement S1;
49position p;
50@@
51
52* if@p (...) S1 else S1
53
54@script:python depends on org@
55p << cond.p;
56@@
57
58cocci.print_main("WARNING: possible condition with no effect (if == else)",p)
59
60@script:python depends on report@
61p << cond.p;
62@@
63
64coccilib.report.print_report(p[0],"WARNING: possible condition with no effect (if == else)")