David Binderman dcb314@hotmail.com writes:
Hello there,
I ran the static analyser cppcheck over the linux-6.2 source code and got this:
linux-6.2/tools/testing/selftests/powerpc/pmu/sampling_tests/mmcra_thresh_marked_sample_test.c:68:10: style: Same expression '0x3' found multiple times in chain of '&' operators. [duplicateExpression]
Thanks.
Source code is
FAIL_IF(EV_CODE_EXTRACT(event.attr.config, sample & 0x3) != get_mmcra_sample_mode(get_reg_value(intr_regs, "MMCRA"), 4));but
#define EV_CODE_EXTRACT(x, y) \ ((x >> ev_shift_##y) & ev_mask_##y)
Given the token pasting, I very much doubt an expression like "sample & 0x3" will work correctly. Same thing on the line above
FAIL_IF(EV_CODE_EXTRACT(event.attr.config, sample >> 2) != get_mmcra_rand_samp_elig(get_reg_value(intr_regs, "MMCRA"), 4));"sample >> 2" doesn't look like a valid token to me.
It expands to:
if ((((event.attr.config >> ev_shift_sample >> 2) & ev_mask_sample >> 2) != get_mmcra_rand_samp_elig(get_reg_value(intr_regs, "MMCRA"), 4)))
Which AFAICS is valid, and does compile.
Whether it's what the author actually intended is less clear.
And the other example with & 0x3 seems obviously wrong, it expands to:
if ((((event.attr.config >> ev_shift_sample & 0x3) & ev_mask_sample & 0x3) != get_mmcra_sample_mode(get_reg_value(intr_regs, "MMCRA"), 4)))
The shift is 24, so bitwise anding it with 0x3 gets 0 which doesn't seem likely to be what was intended.
cheers