Re: [PATCH] Re: 2.6.12: itimer_real timers don't survive execve() any more

[George Anzinger <george@mvista.com>]

Roland McGrath wrote:
>>There are other concerns.  Let me see if I understand this.  A thread 
>>(other than the leader) can exec and we then need to change the 
>>real_timer to wake the new task which will NOT be using the same task 
>>struct.
> 
> 
> That's correct.  de_thread will turn the thread calling exec into the new
> leader and kill off all the other threads, including the old leader.  The
> exec'ing thread's existing task_struct is reassigned to the PID of the
> original leader.
> 
> 
>>My looking at the code shows that the thread leader can exit and then 
>>stays around as a zombi until the last thread in the group exits.  
> 
> 
> That is correct.
> 
> 
>>If an alarm comes during this wait I suspect it will wake this zombi and
>>cause problems.
> 
> 
> You are mistaken.  The signal code handles process signals sent when the
> leader is a zombie.  The group leader sticks around with the PID that
> matches the TGID, until there are no live threads with its TGID.  That is
> how process-wide kill can still work.

Yes, I see, traced through the signal delivery.  So Linus' patch as well 
as the regression of Ingo's will fix all of this.  Right?

-- 
George Anzinger   george@mvista.com
HRT (High-res-timers):  http://sourceforge.net/projects/high-res-timers/