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

[Chung-Lin Tang <chunglin_tang@mentor.com>]

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,
>>>>                           // b depends on c (b,c linked to object a in fixed order)
>>>>
>>>>       a->b->c;{+a;%a;-a}  // a, b, c serially dependent, main program uses
>>>>                           // dlopen/dlsym/dlclose on object a
>>>>
>>>>       a->b->c;{}!->[abc]  // a, b, c serially dependent; multiple tests generated
>>>>                           // to test all permutations of a, b, c ordering linked
>>>>                           // to main program
>>>>
>>>>      (Above is just a short description of what the script can do, more
>>>>       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>
>>>>
>>>>           [BZ #17645]
>>>>           [BZ #15311]
>>>>           [BZ #15310]
>>>>           * elf/Makefile (test_dso_ordering): New make function.
>>>>           (tst-dso-ordering[123456789]): Define new DSO sorting tests.
>>>>           (tst-bz15311): Testcase from #15311.
>>>>           * scripts/dso-ordering-test.py: New script.
> 
>