diff options
| -rw-r--r-- | scripts/coccinelle/misc/cond_no_effect.cocci | 64 |
1 files changed, 64 insertions, 0 deletions
diff --git a/scripts/coccinelle/misc/cond_no_effect.cocci b/scripts/coccinelle/misc/cond_no_effect.cocci new file mode 100644 index 000000000000..8467dbd1c465 --- /dev/null +++ b/scripts/coccinelle/misc/cond_no_effect.cocci @@ -0,0 +1,64 @@ +///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)") |