[PATCH] nptl: Use SA_RESTART for SIGCANCEL handler

[Adhemerval Zanella]

On 22/06/2021 15:33, Florian Weimer wrote:
> * Adhemerval Zanella:
> 
>> On 18/06/2021 08:38, Florian Weimer wrote:
>>> * Adhemerval Zanella via Libc-alpha:
>>>
>>>> The usage of signals to implementation pthread cancellation is an
>>>> implementation detail and should not be visible through cancellation
>>>> entrypoints.
>>>>
>>>> However now that pthread_cancel always send the SIGCANCEL, some
>>>> entrypoint might be interruptable and return EINTR to the caller
>>>> (for instance on sem_wait).
>>>>
>>>> Using SA_RESTART hides this, since the cancellation handler should
>>>> either act uppon cancellation (if asynchronous cancellation is enable)
>>>> or ignore the cancellation internal signal.
>>>
>>> I think this still needs a NEWS entry because there have been kernel
>>> bugs in this area (e.g. in CIFS).
>>
>> Ok, I have added the following on "Deprecated and removed features, and 
>> other changes affecting compatibility"
>>
>> * The pthread cancellation handler is now setup with SA_RESTART.  It should
>>   not be visible to application since the cancellation handler should either 
>>   act uppon cancellation (if asynchronous cancellation is enabled) or
>>   ignore the cancellation internal signal.
> 
> The key change is: The cancellation signal is now sent in more cases,
> but this should be transparent to the application due to SA_RESTART.

I am not sure if we really need to describe this implementation detail
on a NEWS entry.