![Nicholas Mc Guire](/assets/img/avatar_default.png)
Report code constructs where the if and else branch are functionally identical. In cases where this is intended it really should be documented - most reported cases probably are bugs. Signed-off-by: Nicholas Mc Guire <hofrat@osadl.org> Signed-off-by: Michal Marek <mmarek@suse.com>
65 lines
2 KiB
Plaintext
65 lines
2 KiB
Plaintext
///Find conditions where if and else branch are functionally
|
|
// identical.
|
|
//
|
|
// There can be false positives in cases where the positional
|
|
// information is used (as with lockdep) or where the identity
|
|
// is a placeholder for not yet handled cases.
|
|
// Unfortunately there also seems to be a tendency to use
|
|
// the last if else/else as a "default behavior" - which some
|
|
// might consider a legitimate coding pattern. From discussion
|
|
// on kernelnewbies though it seems that this is not really an
|
|
// accepted pattern and if at all it would need to be commented
|
|
//
|
|
// In the Linux kernel it does not seem to actually report
|
|
// false positives except for those that were documented as
|
|
// being intentional.
|
|
// the two known cases are:
|
|
// arch/sh/kernel/traps_64.c:read_opcode()
|
|
// } else if ((pc & 1) == 0) {
|
|
// /* SHcompact */
|
|
// /* TODO : provide handling for this. We don't really support
|
|
// user-mode SHcompact yet, and for a kernel fault, this would
|
|
// have to come from a module built for SHcompact. */
|
|
// return -EFAULT;
|
|
// } else {
|
|
// /* misaligned */
|
|
// return -EFAULT;
|
|
// }
|
|
// fs/kernfs/file.c:kernfs_fop_open()
|
|
// * Both paths of the branch look the same. They're supposed to
|
|
// * look that way and give @of->mutex different static lockdep keys.
|
|
// */
|
|
// if (has_mmap)
|
|
// mutex_init(&of->mutex);
|
|
// else
|
|
// mutex_init(&of->mutex);
|
|
//
|
|
// All other cases look like bugs or at least lack of documentation
|
|
//
|
|
// Confidence: Moderate
|
|
// Copyright: (C) 2016 Nicholas Mc Guire, OSADL. GPLv2.
|
|
// Comments:
|
|
// Options: --no-includes --include-headers
|
|
|
|
virtual org
|
|
virtual report
|
|
|
|
@cond@
|
|
statement S1;
|
|
position p;
|
|
@@
|
|
|
|
* if@p (...) S1 else S1
|
|
|
|
@script:python depends on org@
|
|
p << cond.p;
|
|
@@
|
|
|
|
cocci.print_main("WARNING: possible condition with no effect (if == else)",p)
|
|
|
|
@script:python depends on report@
|
|
p << cond.p;
|
|
@@
|
|
|
|
coccilib.report.print_report(p[0],"WARNING: possible condition with no effect (if == else)")
|