From: Oleg Nesterov <oleg@tv-sign.ru>
To: Andrew Morton <akpm@osdl.org>
Cc: Ingo Molnar <mingo@elte.hu>, Thomas Gleixner <tglx@linutronix.de>,
Steven Rostedt <rostedt@goodmis.org>,
linux-kernel@vger.kernel.org
Subject: [PATCH 2/3] futex_find_get_task: don't take tasklist_lock
Date: Mon, 21 Aug 2006 21:06:21 +0400 [thread overview]
Message-ID: <20060821170621.GA1643@oleg> (raw)
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;
}
next reply other threads:[~2006-08-21 12:42 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-08-21 17:06 Oleg Nesterov [this message]
2006-08-22 10:44 ` [PATCH 2/3] futex_find_get_task: don't take tasklist_lock Ingo Molnar
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