tree 0cc68e5daea5d4532a0225aa47cce193a32f6655
parent 7775aa7690c26b3c5606090a43533a7a7429eb91
author Oleg Nesterov <oleg@tv-sign.ru> 1140030804 +0300
committer Linus Torvalds <torvalds@g5.osdl.org> 1140027683 -0800

[PATCH] fix kill_proc_info() vs CLONE_THREAD race

There is a window after copy_process() unlocks ->sighand.siglock
and before it adds the new thread to the thread list.

In that window __group_complete_signal(SIGKILL) will not see the
new thread yet, so this thread will start running while the whole
thread group was supposed to exit.

I beleive we have another good reason to place attach_pid(PID/TGID)
under ->sighand.siglock. We can do the same for

	release_task()->__unhash_process()

	de_thread()->switch_exec_pids()

After that we don't need tasklist_lock to iterate over the thread
list, and we can simplify things, see for example do_sigaction()
or sys_times().

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Roland McGrath <roland@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>