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65 lines
2.1 KiB
65 lines
2.1 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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///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. |
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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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