Re: [PATCH 3/5] lib/bitmap: add test for bitmap_{from,to}_arr64

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On 2/27/23 06:46, Alexander Lobakin wrote:
From: Yury Norov <yury.norov@xxxxxxxxx>
Date: Sat, 25 Feb 2023 16:06:45 -0800

On Sat, Feb 25, 2023 at 04:05:02PM -0800, Yury Norov wrote:
On Sat, Feb 25, 2023 at 10:47:02AM -0800, Guenter Roeck wrote:
Hi,

On Thu, Apr 28, 2022 at 01:51:14PM -0700, Yury Norov wrote:
Test newly added bitmap_{from,to}_arr64() functions similarly to
already existing bitmap_{from,to}_arr32() tests.

Signed-off-by: Yury Norov <yury.norov@xxxxxxxxx>

Ever since this test is in the tree, several of my boot tests show
lots of messages such as

test_bitmap: bitmap_to_arr64(nbits == 1): tail is not safely cleared: 0xa5a5a5a500000001 (must be 0x0000000000000001)

Hmmm, the whole 4 bytes weren't touched.

test_bitmap: bitmap_to_arr64(nbits == 2): tail is not safely cleared: 0xa5a5a5a500000001 (must be 0x0000000000000003)
test_bitmap: bitmap_to_arr64(nbits == 3): tail is not safely cleared: 0xa5a5a5a500000001 (must be 0x0000000000000007)

This is where it gets worse...

...
test_bitmap: bitmap_to_arr64(nbits == 927): tail is not safely cleared: 0xa5a5a5a500000000 (must be 0x000000007fffffff)
test_bitmap: bitmap_to_arr64(nbits == 928): tail is not safely cleared: 0xa5a5a5a580000000 (must be 0x00000000ffffffff)

I don't see the pattern how the actual result gets generated. But the
problem is in the bitmap code rather than in the subtest -- "must be"s
are fully correct.

Given that the 0xa5s are present in the upper 32 bits, it is Big Endian
I guess? Maybe even 32-bit Big Endian? Otherwise I'd start concerning
how comes it doesn't reproduce on x86_64s :D


It does reproduce on 32-bit x86 builds, and as far as I can see
it is only seen with 32-bit little endian systems.

Guenter


This may be a real problem. Can you share what's the system is? What's
endianness and register length?

+ Alexander Lobakin, the author of the exact subtest.

Forgot to add

Oh, thanks for letting me know!

but then:

test_bitmap: all 6550 tests passed

It's because corresponding error path doesn't increment failed_tests
counter. I'll send a fix shortly.

[...]

Thanks,
Olek




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