Ping x2 Re: [PATCH 1/2][RFC] #17645, fix slow DSO sorting behavior in dynamic loader

[Chung-Lin Tang]

Ping?

On 2019/11/14 5:58 PM, Chung-Lin Tang wrote:
> On 2019/10/31 9:13 PM, Carlos O'Donell wrote:
>> On 10/8/19 2:22 AM, Chung-Lin Tang wrote:
>>> Ping again.
>>
>> I have these applied and I'm putting this through testing.
> 
> Hi Carlos,
> Thanks for the testing, wonder how it went?
> 
> Thanks,
> Chung-Lin
> 
>>> On 2019/9/17 5:55 PM, Chung-Lin Tang wrote:
>>>> Ping?
>>>>
>>>> On 2019/7/21 1:50 AM, Chung-Lin Tang wrote:
>>>>> Hi, this patch is our attempt at resolving the slow shared object sorting
>>>>> situation in #17645, #15310, and some effort at #15311.  I realize this is
>>>>> pretty unsuitable timing to be submitting a patch of such nature now (probably
>>>>> way too late to be included into 2.30), but still sending now anyways as this
>>>>> will probably need quite some discussion before being approved.
>>>>>
>>>>> Prior attempts at solving this slow sorting behavior appeared to have failed
>>>>> due to inadequate proposed testing, therefore cannot convince reviewers to
>>>>> touch what seems to be perceived as a sensitive and easy to break part of ld.so.
>>>>>
>>>>> Therefore the first part of this patch is not a change to the dynamic loader
>>>>> code proper, but a testing framework for constructing DSO sorting tests.
>>>>> It consists of a new Python script 'dso-ordering-test.py' that serves to
>>>>> generate both testcase source files and the needed Makefile fragments from
>>>>> a short description string, for example:
>>>>>
>>>>>       a->b->c->d          // four objects linked one after another
>>>>>
>>>>>       a->[bc]->d;b->c     // a depends on b and c, which both depend on d,
>>>>> Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â  // b depends on c (b,c linked to object a in fixed order)
>>>>>
>>>>> Â Â Â Â Â  a->b->c;{+a;%a;-a}Â  // a, b, c serially dependent, main program uses
>>>>> Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â  // dlopen/dlsym/dlclose on object a
>>>>>
>>>>> Â Â Â Â Â  a->b->c;{}!->[abc]Â  // a, b, c serially dependent; multiple tests generated
>>>>> Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â  // to test all permutations of a, b, c ordering linked
>>>>> Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â  // to main program
>>>>>
>>>>> Â Â Â Â  (Above is just a short description of what the script can do, more
>>>>> Â Â Â Â Â  documentation is in the script comments.)
>>>>>
>>>>> and, a patch to glibc/elf/Makefile which uses this script to add a few
>>>>> DSO sorting testcases.  The description string notation and output form of the
>>>>> generated testcases is short enough that both the test descriptions
>>>>> and expected outcomes can all directly be specified in the Makefile.
>>>>>
>>>>> In terms of the tests I added using this script, I am not completely sure they are
>>>>> (together with existing tests) adequate to prove algorithmic integrity in face
>>>>> of any ld.so code changes, but the script should provide a solid tool to further
>>>>> improve on coverage.  Also welcome suggestions if the current features are still
>>>>> lacking in expressing some case of shared object relations, or if the documentation
>>>>> still feels unclear.
>>>>>
>>>>> Thanks,
>>>>> Chung-Lin
>>>>>
>>>>> 2019-07-20  Chung-Lin Tang  <cltang@codesourcery.com>
>>>>>
>>>>> Â Â Â Â Â Â Â Â Â  [BZ #17645]
>>>>> Â Â Â Â Â Â Â Â Â  [BZ #15311]
>>>>> Â Â Â Â Â Â Â Â Â  [BZ #15310]
>>>>> Â Â Â Â Â Â Â Â Â  * elf/Makefile (test_dso_ordering): New make function.
>>>>> Â Â Â Â Â Â Â Â Â  (tst-dso-ordering[123456789]): Define new DSO sorting tests.
>>>>> Â Â Â Â Â Â Â Â Â  (tst-bz15311): Testcase from #15311.
>>>>> Â Â Â Â Â Â Â Â Â  * scripts/dso-ordering-test.py: New script.
>>
>>