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

[Roland McGrath <roland@redhat.com>]

> 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.


Thanks,
Roland