Re: heavy handed exit() in latest BK

[Ingo Molnar <mingo@elte.hu>]

Roland,

there are two bugs in the signal code still:

 - a read_lock(&tasklist_lock) is missing around the group_send_sig_info()
   in send_sig_info().

 - session-IDs and group-IDs are set outside the tasklist lock. This
   causes breakage in the USB code. The correct fix is to do this:

void __set_special_pids(pid_t session, pid_t pgrp)
{
        struct task_struct *curr = current;

        if (curr->session != session) {
                detach_pid(curr, PIDTYPE_SID);
                curr->session = session;
                attach_pid(curr, PIDTYPE_SID, session);
        }
        if (curr->pgrp != pgrp) {
                detach_pid(curr, PIDTYPE_PGID);
                curr->pgrp = pgrp;
                attach_pid(curr, PIDTYPE_PGID, pgrp);
        }
}

void set_special_pids(pid_t session, pid_t pgrp)
{
        write_lock_irq(&tasklist_lock);
        __set_special_pids(session, pgrp);
        write_unlock_irq(&tasklist_lock);
}

and then update all places that do:

-	current->session = 1;
-	current->pgrp = 1;

to:

+	set_special_pids(1, 1);

otherwise we change the PIDs without properly rehashing them.

	Ingo