Re: [PATCH v3 1/4] util: Add thread-safe qemu_strerror() function

[Yohei Kojima]

On 2023/04/06 17:57, Alex Bennée wrote:
> 
> Yohei Kojima <y-koj@outlook.jp> writes:
> 
>> On 2023/03/31 4:06, Markus Armbruster wrote:
>>> Yohei Kojima <y-koj@outlook.jp> writes:
>>>
>>>> Add qemu_strerror() which follows the POSIX specification for
>>>> strerror(). While strerror() is not guaranteed to be thread-safe, this
>>>> function is thread-safe.
>>>
>>> Why not g_strerror()?
>>>
>>
>> Because g_strerror() uses mutex in its implementation and there is a
>> risk to occur the deadlock. If one thread enters g_strerror() (soon the
>> mutex is locked), then another thread calls fork(), and the forked
>> child process try to call g_strerror(), then deadlock occurs.
> 
> I think we should mention this avoids the deadlock in the commit
> message. With that:
> 
> Reviewed-by: Alex Bennée <alex.bennee@linaro.org>

Thank you for the review. I will address that in the next version.

> 
> 
>>
>>>> This function is added to solve the following issue:
>>>> https://gitlab.com/qemu-project/qemu/-/issues/416
>>>
>>> The issue even asks for it...
>>>
>>
>> Originally yes, but Daniel told the deadlock (or a mutex starvation)
>> risk for g_strerror() in the later discussion of the issue. Probably I
>> should have mention that in the commit message or the cover letter.
>>
>>>> Signed-off-by: Yohei Kojima <y-koj@outlook.jp>
>>>
> 
>