Re: [PATCH] Re: 2.6.12: itimer_real timers don't survive execve()any more
From: Roland McGrath
Date: Fri Aug 05 2005 - 17:18:10 EST
> 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
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