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Re: [PATCH 2/2] elf: Use nocancel pread64() instead of lseek()+read()
* Carlos O'Donell:
> On 10/20/19 5:37 PM, Lukasz Majewski wrote:
>> On Fri, 18 Oct 2019 16:02:22 -0400
>> Carlos O'Donell <carlos@redhat.com> wrote:
>>
>>> On 10/3/19 9:59 AM, Carlos O'Donell wrote:
>>>> On 8/5/19 5:56 PM, Leandro Pereira wrote:
>>>>> Transforms this, when linking in a shared object:
>>>>>
>>>>> openat(AT_FDCWD, "/lib64/libc.so.6", O_RDONLY|O_CLOEXEC) = 3
>>>>> read(3, "\177ELF\2\1\1\3"..., 832) = 832
>>>>> lseek(3, 792, SEEK_SET) = 792
>>>>> read(3, "\4\0\0\0\24\0\0\0"..., 68) = 68
>>>>> fstat(3, {st_mode=S_IFREG|0755, st_size=6699224, ...}) = 0
>>>>> lseek(3, 792, SEEK_SET) = 792
>>>>> read(3, "\4\0\0\0\24\0\0\0"..., 68) = 68
>>>>> lseek(3, 864, SEEK_SET) = 864
>>>>> read(3, "\4\0\0\0\20\0\0\0"..., 32) = 32
>>>>>
>>>>> Into this:
>>>>>
>>>>> openat(AT_FDCWD, "/lib64/libc.so.6", O_RDONLY|O_CLOEXEC) = 3
>>>>> read(3, "\177ELF\2\1\1\3"..., 832) = 832
>>>>> pread(3, "\4\0\0\0\24\0\0\0"..., 68, 792) = 68
>>>>> fstat(3, {st_mode=S_IFREG|0755, st_size=6699224, ...}) = 0
>>>>> pread(3, "\4\0\0\0\24\0\0\0"..., 68, 792) = 68
>>>>> pread(3, "\4\0\0\0\20\0\0\0"..., 32, 864) = 32
>>>>>
>>>>> 2019-08-05 Leandro Pereira <leandro.pereira@microsoft.com>
>>>>>
>>>>> * elf/dl-load.c: Use __pread64_nocancel() instead of
>>>>> __lseek()+ __read_nocancel().
>>>>> * sysdeps/x86/dl-prop.h: Likewise.
>>>>
>>>> OK for master. I'll push after testing with bmg. No regressions on
>>>> x86_64.
>>>>
>>>> Reviewed-by: Carlos O'Donell <carlos@redhat.com>
>>>
>>> Pushed.
>>>
>>
>> Unfortunately, I've found a regression on HURD when using
>> build-many-glibcs.py (for testing some other code):
>>
>> ../glibc-many-build/src/glibc/libio/../sysdeps/posix/libc_fatal.c:161:
>> multiple definition of `__libc_fatal';
>> ../glibc-many-build/build/glibcs/i686-gnu/glibc/elf/dl-allobjs.os:/work/lukma/glibc/glibc-many-build/src/glibc/elf/dl-minimal.c\
>> :188: first defined here
>>
>> To reproduce:
>> ../src/scripts/build-many-glibcs.py
>> <path>/glibc/glibc-many-build glibcs i686-gnu
>>
>> emacs logs/glibcs/i686-gnu/004-glibcs-i686-gnu-build-log.txt
>
> Thanks. I didn't see this. Let me start another build.
I think I know what's going on and I'm looking to a fix.
We shouldn't let such build regressions linger for so long.