[PATCH] do __unhash_process() under ->siglock
This patch moves __unhash_process() call from realease_task() to __exit_signal(), so __detach_pid() is called with ->siglock held. This means we don't need tasklist_lock to iterate over thread group anymore: copy_process() was already changed to do attach_pid() under ->siglock. Eric's "pidhash-kill-switch_exec_pids.patch" from -mm changed de_thread() so it doesn't touch PIDTYPE_TGID. NOTE: de_thread() still needs some attention. It still changes task->pid lockless. Taking ->sighand.siglock here allows to do more tasklist_lock removals. Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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@ -112,6 +112,8 @@ static void __exit_signal(struct task_struct *tsk)
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sig = NULL; /* Marker for below. */
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}
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__unhash_process(tsk);
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tsk->signal = NULL;
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cleanup_sighand(tsk);
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spin_unlock(&sighand->siglock);
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@ -140,8 +142,6 @@ repeat:
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BUG_ON(!list_empty(&p->ptrace_list) || !list_empty(&p->ptrace_children));
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__exit_signal(p);
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__unhash_process(p);
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/*
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* If we are the last non-leader member of the thread
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* group, and the leader is zombie, then notify the
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