Re: [PATCH] task: Make task list manipulations RCU safe.
From: Oleg Nesterov
Date: Tue Mar 14 2006 - 12:37:20 EST
Some questions.
first_tgid:
...
for (; pos && pid_alive(pos); pos = next_task(pos))
I think this patch makes this 'pid_alive(pos)' unneeded?
next_tgid:
rcu_read_lock();
pos = start;
if (pid_alive(start))
pos = next_task(start);
if (pid_alive(pos) && (pos != &init_task)) {
get_task_struct(pos);
goto done;
}
The first 'pid_alive()' check is quite understandable.
What about the second one? I beleive, now it is unneeded
as well. The same for first_tid/next_tid.
Also, first_tid() does 'task_lock(leader)' while reading
->signal->count. Why? ->signal is protected by ->siglock,
but we don't need any locks because ->signal is rcu safe.
Same for proc_task_getattr(), s/task_lock/rcu_read_lock/.
Oleg.
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