[PATCH v2 1/2] lib: test_scanf: Remove pointless use of type_min() with unsigned types
From: Richard Fitzgerald <rf@opensource.cirrus.com>
Date: 2021-05-25 11:07:48
Also in:
lkml
Subsystem:
library code, the rest · Maintainers:
Andrew Morton, Linus Torvalds
sparse was producing warnings of the form: sparse: cast truncates bits from constant value (ffff0001 becomes 1) There is no actual problem here. Using type_min() on an unsigned type results in an (expected) truncation. However, there is no need to test an unsigned value against type_min(). The minimum value of an unsigned is obviously 0, and any value cast to an unsigned type is >= 0, so for unsigneds only type_max() need be tested. This patch also takes the opportunity to clean up the implementation of simple_numbers_loop() to use a common pattern for the positive and negative test. Reported-by: kernel test robot <redacted> Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com> --- lib/test_scanf.c | 13 ++++++------- 1 file changed, 6 insertions(+), 7 deletions(-)
diff --git a/lib/test_scanf.c b/lib/test_scanf.c
index 8d577aec6c28..48ff5747a4da 100644
--- a/lib/test_scanf.c
+++ b/lib/test_scanf.c@@ -187,8 +187,8 @@ static const unsigned long long numbers[] __initconst = { #define value_representable_in_type(T, val) \ (is_signed_type(T) \ ? ((long long)(val) >= type_min(T)) && ((long long)(val) <= type_max(T)) \ - : ((unsigned long long)(val) >= type_min(T)) && \ - ((unsigned long long)(val) <= type_max(T))) + : ((unsigned long long)(val) <= type_max(T))) + #define test_one_number(T, gen_fmt, scan_fmt, val, fn) \ do { \
@@ -204,12 +204,11 @@ do { \ int i; \ \ for (i = 0; i < ARRAY_SIZE(numbers); i++) { \ - if (!value_representable_in_type(T, numbers[i])) \ - continue; \ + if (value_representable_in_type(T, numbers[i])) \ + test_one_number(T, gen_fmt, scan_fmt, \ + numbers[i], fn); \ \ - test_one_number(T, gen_fmt, scan_fmt, numbers[i], fn); \ - \ - if (is_signed_type(T)) \ + if (value_representable_in_type(T, -numbers[i])) \ test_one_number(T, gen_fmt, scan_fmt, \ -numbers[i], fn); \ } \
--
2.20.1