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c8990359d4
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
2.0 KiB
Plaintext
65 lines
2.0 KiB
Plaintext
///Find conditions where if and else branch are functionally
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// identical.
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//
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// There can be false positives in cases where the positional
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// information is used (as with lockdep) or where the identity
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// is a placeholder for not yet handled cases.
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// Unfortunately there also seems to be a tendency to use
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// the last if else/else as a "default behavior" - which some
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// might consider a legitimate coding pattern. From discussion
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// on kernelnewbies though it seems that this is not really an
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// accepted pattern and if at all it would need to be commented
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//
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// In the Linux kernel it does not seem to actually report
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// false positives except for those that were documented as
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// being intentional.
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// the two known cases are:
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// arch/sh/kernel/traps_64.c:read_opcode()
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// } else if ((pc & 1) == 0) {
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// /* SHcompact */
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// /* TODO : provide handling for this. We don't really support
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// user-mode SHcompact yet, and for a kernel fault, this would
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// have to come from a module built for SHcompact. */
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// return -EFAULT;
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// } else {
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// /* misaligned */
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// return -EFAULT;
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// }
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// fs/kernfs/file.c:kernfs_fop_open()
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// * Both paths of the branch look the same. They're supposed to
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// * look that way and give @of->mutex different static lockdep keys.
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// */
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// if (has_mmap)
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// mutex_init(&of->mutex);
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// else
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// mutex_init(&of->mutex);
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//
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// All other cases look like bugs or at least lack of documentation
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//
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// Confidence: Moderate
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// Copyright: (C) 2016 Nicholas Mc Guire, OSADL. GPLv2.
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// Comments:
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// Options: --no-includes --include-headers
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virtual org
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virtual report
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@cond@
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statement S1;
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position p;
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@@
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* if@p (...) S1 else S1
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@script:python depends on org@
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p << cond.p;
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@@
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cocci.print_main("WARNING: possible condition with no effect (if == else)",p)
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@script:python depends on report@
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p << cond.p;
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@@
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coccilib.report.print_report(p[0],"WARNING: possible condition with no effect (if == else)")
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