This was already discussed.
Yes, we can add list_head into signal_struct. But this breaks, say,
thread_group_empty() and the similar code. This is fixeable.
But. We need to convert the code which does while_each_thread(g, t) to
use list_for_each(t, head). And, if g != group_leader this can't work.
Not to mention the increase of sizeof(signal_struct).
Oleg.
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