[PATCH] clone.2: note EINVAL when exit_signal + bad flags

[Alejandro Colomar]

Hi Jack,

Please keep glibc and Carlos in the loop.

Thanks,

Alex

On 12/14/22 22:00, Jack Pearson wrote:
> On 12/12/22 18:53, Carlos O'Donell wrote:
>> On 12/9/22 14:49, Alejandro Colomar wrote:
>>> Hi Jack,
>>>
>>> On 12/2/22 23:44, Jack Pearson wrote:
>>>> Document that Linux will report EINVAL when exit_signal is specified and
>>>> either CLONE_THREAD or CLONE_PARENT is specified.
>>>>
>>>>   From clone3_args_valid in Linux:
>>>> ```
>>>>      if ((kargs->flags & (CLONE_THREAD | CLONE_PARENT)) &&
>>>>          kargs->exit_signal)
>>>>          return false;
>>>> ```
>>>>
>>>> I have verified that this happens on my kernel with a small program, and
>>>> that this doesn't happen with normal `clone` through the glibc helper.
>>>
>>> Could you please also send a test program with the glibc wrapper?
>>>
>>> BTW, glibc has a clone3(2) wrapper since last year.  It would be interesting 
>>> to document it instead of the raw syscall.
>>
>> glibc does not have a clone3 wrapper.
>>
>> glibc has an internal non-exported __clone3 interface that we use for pthreads,
>> and likely soon for posix_spawn.
>>
>> We have not yet chosen to export clone3 as a public global symbol that developers
>> can use.
>>
> 
> Ahhh, that's why I couldn't find it in the headers.
> 
> Incoming patch with the glibc clone wrapper test program.
> 
> 
> Jack

-- 
<http://www.alejandro-colomar.es/>
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