[RFC PATCH glibc v2] pthread_setspecific: Provide signal-safety across keys

[Szabolcs Nagy]

On 18/10/17 06:33, Florian Weimer wrote:
> * Mathieu Desnoyers:
> 
>> @@ -327,7 +328,7 @@ __nptl_deallocate_tsd (void)
>>  	    {
>>  	      /* The first block is allocated as part of the thread
>>  		 descriptor.  */
>> -	      free (level2);
>> +	      (void) munmap (level2, PTHREAD_KEY_2NDLEVEL_SIZE * sizeof (*level2));
>>  	      THREAD_SETMEM_NC (self, specific, cnt, NULL);
> 
> I think __nptl_deallocate_tsd needs to disable signals as well, even
> when the level2 pointer is NULL, and keep them disabled until the
> thread exits.  This is not a localized change; I don't know if it is
> safe.
> 

dtors must not run with signals blocked (posix does not
say that dtors may see changed signal mask)

i think it's the user's fault if there is async
pthread_getspecific call while a thread is exiting.
the user can block the signals before thread exit
if that's the intended behaviour.