From: Oleg Nesterov <oleg@tv-sign.ru>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@elte.hu>, Andrew Morton <akpm@osdl.org>,
linux-kernel@vger.kernel.org
Subject: Re: [patch 1/3] Drop tasklist lock in do_sched_setscheduler
Date: Sun, 25 Jun 2006 04:50:45 +0400 [thread overview]
Message-ID: <20060625005045.GA155@oleg> (raw)
Thomas Gleixner wrote:
>
> There is no need to hold tasklist_lock across the setscheduler call, when we
> pin the task structure with get_task_struct(). Interrupts are disabled in
> setscheduler anyway and the permission checks do not need interrupts disabled.
>
> --- linux-2.6.17-mm.orig/kernel/sched.c 2006-06-22 10:26:11.000000000 +0200
> +++ linux-2.6.17-mm/kernel/sched.c 2006-06-22 10:26:11.000000000 +0200
> @@ -4140,8 +4140,10 @@
> read_unlock_irq(&tasklist_lock);
> return -ESRCH;
> }
> - retval = sched_setscheduler(p, policy, &lparam);
> + get_task_struct(p);
> read_unlock_irq(&tasklist_lock);
> + retval = sched_setscheduler(p, policy, &lparam);
> + put_task_struct(p);
> return retval;
> }
But we don't need read_lock(tasklist) and get_task_struct(p) at all?
rcu_read_lock/rcu_read_unlock is enough, no?
Oleg.
next reply other threads:[~2006-06-24 20:50 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-06-25 0:50 Oleg Nesterov [this message]
2006-06-25 15:35 ` [patch 1/3] Drop tasklist lock in do_sched_setscheduler Thomas Gleixner
-- strict thread matches above, loose matches on Subject: below --
2006-06-22 9:08 [patch 0/3] rtmutex: Propagate priority setting into lock chains Thomas Gleixner
2006-06-22 9:08 ` [patch 1/3] Drop tasklist lock in do_sched_setscheduler Thomas Gleixner
2006-06-23 1:48 ` Andrew Morton
2006-06-23 6:01 ` Thomas Gleixner
2006-06-24 8:07 ` Andrew Morton
2006-06-24 8:25 ` Thomas Gleixner
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