linux-kernel - Re: [PATCH 2/2] bitmap: Add test for bitmap

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Date:   Mon, 15 Jun 2020 13:08:25 +0200
From:   Stefano Brivio <sbrivio@...hat.com>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     Alexander Gordeev <agordeev@...ux.ibm.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Yury Norov <yury.norov@...il.com>,
        Rasmus Villemoes <linux@...musvillemoes.dk>,
        Pablo Neira Ayuso <pablo@...filter.org>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] bitmap: Add test for bitmap_cut()

On Mon, 15 Jun 2020 12:46:16 +0300
Andy Shevchenko <andriy.shevchenko@...ux.intel.com> wrote:

> On Mon, Jun 15, 2020 at 12:41:55PM +0300, Andy Shevchenko wrote:
> > On Sun, Jun 14, 2020 at 07:40:54PM +0200, Stefano Brivio wrote:  
> > > Inspired by an original patch from Yury Norov: introduce a test for
> > > bitmap_cut() that also makes sure functionality is as described for
> > > partially overlapping src and dst.  
> > 
> > Taking into account recent fixes for BE 64-bit, do we have test cases for a such?  
> 
> It might be enough to have only these, but perhaps s390 guys can help?

There's no behaviour difference due to endianness in this test itself --
just word size was a topic, hence that BITS_PER_LONG usage with
redundant values (checked on i686).

That is, if you have:
	{ 0x0000ffffUL, 0x5a5a5a5aUL, 0x5a5a5a5aUL, 0x5a5a5a5aUL },

then 1 as array subscript always denotes the second item (from the left)
there, it doesn't matter how and where different architectures store it.

Indeed, if bitmap_cut() directly addressed single bytes within the
words, I would need to pay special attention there. The values I picked
for these tests are also meant to show any issue in that sense.

> Alexander, can you apply this patch (w/o the first one, which is suppose to
> fix) and confirm that you have test case failure, followed by applying first
> one and confirm a fix?

I did that already on s390x (of course, I thought :)), I can confirm
that. Without patch 1/2 the test also fails there:

[   20.917848] test_bitmap: [lib/test_bitmap.c:666] bitmaps contents differ: expected "0-16,18-19,21,24,26-27,29", got "1,3-4,6,9,11-12,14,16,18-19,21,24,26-27,29"

If Alexander wants to test this on a z14 or z15, sure, it won't harm.

By the way, tests for 'parse', 'parse_user' and 'parselist' report
issues:

[   20.390401] test_bitmap: loaded.
[   20.394839] test_bitmap: parse: 4: input is 1, result is 0x100000000, expected 0x1
[   20.395011] test_bitmap: parse: 5: input is deadbeef, result is 0xdeadbeef00000000, expected 0xdeadbeef
[   20.395059] test_bitmap: parse: 6: input is 1,0, result is 0x1, expected 0x100000000
[   20.395099] test_bitmap: parse: 7: input is deadbeef,
               ,0,1, result is 0x1, expected 0xdeadbeef
[   20.396696] test_bitmap: parse: 8: input is deadbeef,1,0, result is 0x1, expected 0x100000000
[   20.396735] test_bitmap: parse: 9: input is baadf00d,deadbeef,1,0, result is 0x1, expected 0x100000000
[   20.396835] test_bitmap: parse: 10: input is badf00d,deadbeef,1,0, errno is -75, expected 0
[   20.396878] test_bitmap: parse: 11: input is badf00d,deadbeef,1,0, errno is -75, expected 0
[   20.396913] test_bitmap: parse: 12: input is   badf00d,deadbeef,1,0  , errno is -75, expected 0
[   20.396957] test_bitmap: parse: 13: input is  , badf00d,deadbeef,1,0 , , errno is -75, expected 0
[   20.396983] test_bitmap: parse: 14: input is  , badf00d, ,, ,,deadbeef,1,0 , , errno is -75, expected 0
[   20.397052] test_bitmap: parse: 16: input is 3,0, errno is 0, expected -75
[   20.397712] test_bitmap: parse_user: 4: input is 1, result is 0x100000000, expected 0x1
[   20.397832] test_bitmap: parse_user: 5: input is deadbeef, result is 0xdeadbeef00000000, expected 0xdeadbeef
[   20.397928] test_bitmap: parse_user: 6: input is 1,0, result is 0x1, expected 0x100000000
[   20.398022] test_bitmap: parse_user: 7: input is deadbeef,
               ,0,1, result is 0x1, expected 0xdeadbeef
[   20.398116] test_bitmap: parse_user: 8: input is deadbeef,1,0, result is 0x1, expected 0x100000000
[   20.398209] test_bitmap: parse_user: 9: input is baadf00d,deadbeef,1,0, result is 0x1, expected 0x100000000
[   20.398301] test_bitmap: parse_user: 10: input is badf00d,deadbeef,1,0, errno is -75, expected 0
[   20.398393] test_bitmap: parse_user: 11: input is badf00d,deadbeef,1,0, errno is -75, expected 0
[   20.398484] test_bitmap: parse_user: 12: input is   badf00d,deadbeef,1,0  , errno is -75, expected 0
[   20.398574] test_bitmap: parse_user: 13: input is  , badf00d,deadbeef,1,0 , , errno is -75, expected 0
[   20.398666] test_bitmap: parse_user: 14: input is  , badf00d, ,, ,,deadbeef,1,0 , , errno is -75, expected 0
[   20.398794] test_bitmap: parse_user: 16: input is 3,0, errno is 0, expected -75
[   20.399906] test_bitmap: parselist: 14: input is '0-2047:128/256' OK, Time: 2641
[   20.400914] test_bitmap: parselist_user: 14: input is '0-2047:128/256' OK, Time: 19961
[   20.421406] test_bitmap: all 1679 tests passed

and at a glance those *seem* to be bugs in the tests themselves, not in
the actual functions they test. Sure, they should be fixed, but I can't
take care of that right now.

-- 
Stefano