Code comparing unsigned variables with zero using operators < or >= does not make sense. It is always false or true, respectively. However, its presence often indicates bugs in the code. gcc can detect it also using -Wtype-limits switch, but it warns also in correct cases, making too much noise.
Signed-off-by: Andrzej Hajda <a.ha...@samsung.com> --- Hi Julia, This test finds 93 issues in kernel code (with --all-includes) which could be corrected. Some of them are harmless, just unnecessary code, but there are also serious bugs, like: u32 irq = platform_get_irq(...) if (irq < 0) ... unsigned int target = cpumask_any_but(cpu_online_mask, cpu); if (target < 0) ... Regards Andrzej --- .../tests/unsigned_lesser_than_zero.cocci | 37 ++++++++++++++++++++++ 1 file changed, 37 insertions(+) create mode 100644 scripts/coccinelle/tests/unsigned_lesser_than_zero.cocci diff --git a/scripts/coccinelle/tests/unsigned_lesser_than_zero.cocci b/scripts/coccinelle/tests/unsigned_lesser_than_zero.cocci new file mode 100644 index 0000000..6a90510 --- /dev/null +++ b/scripts/coccinelle/tests/unsigned_lesser_than_zero.cocci @@ -0,0 +1,37 @@ +/// Unsigned variables cannot be lesser than zero. Presence of such checks +/// can indicate incorrect variable type or just unnecessary code. +/// +// Confidence: High +// Copyright: (C) 2015 Andrzej Hajda, Samsung Electronics Co., Ltd. GPLv2. +// URL: http://coccinelle.lip6.fr/ +// Options: --include-headers + +virtual context +virtual org +virtual report + +@r depends on context || org || report@ +position p; +typedef u8, u16, u32, u64; +{unsigned char, unsigned short int, unsigned int, unsigned long, unsigned long long, size_t, u8, u16, u32, u64} v; +@@ + +( +*v@p < 0 +| +*v@p >= 0 +) + +@script:python depends on org@ +p << r.p; +@@ + +msg = "WARNING: Unsigned value cannot be lesser than zero" +coccilib.org.print_todo(p[0], msg) + +@script:python depends on report@ +p << r.p; +@@ + +msg = "WARNING: Unsigned value cannot be lesser than zero" +coccilib.report.print_report(p[0], msg) -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/