* [PATCH 2/3] futex_find_get_task: don't take tasklist_lock
@ 2006-08-21 17:06 Oleg Nesterov
2006-08-22 10:44 ` Ingo Molnar
0 siblings, 1 reply; 2+ messages in thread
From: Oleg Nesterov @ 2006-08-21 17:06 UTC (permalink / raw)
To: Andrew Morton; +Cc: Ingo Molnar, Thomas Gleixner, Steven Rostedt, linux-kernel
It is ok to do find_task_by_pid() + get_task_struct() under rcu_read_lock(),
we cand drop tasklist_lock.
Note that testing of ->exit_state is racy with or without tasklist anyway.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
--- 2.6.18-rc4/kernel/futex.c~2_ffgt 2006-08-21 20:32:48.000000000 +0400
+++ 2.6.18-rc4/kernel/futex.c 2006-08-21 20:41:15.000000000 +0400
@@ -389,7 +389,7 @@ static struct task_struct * futex_find_g
{
struct task_struct *p;
- read_lock(&tasklist_lock);
+ rcu_read_lock();
p = find_task_by_pid(pid);
if (!p)
goto out_unlock;
@@ -403,7 +403,7 @@ static struct task_struct * futex_find_g
}
get_task_struct(p);
out_unlock:
- read_unlock(&tasklist_lock);
+ rcu_read_unlock();
return p;
}
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2006-08-21 17:06 [PATCH 2/3] futex_find_get_task: don't take tasklist_lock Oleg Nesterov
2006-08-22 10:44 ` Ingo Molnar
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