From: Oleg Nesterov <oleg@redhat.com>
To: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Ingo Molnar <mingo@elte.hu>,
Ananth N Mavinakayanahalli <ananth@in.ibm.com>,
Anton Arapov <anton@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
Peter Zijlstra <peterz@infradead.org>,
Roland McGrath <roland@hack.frob.com>,
Srikar Dronamraju <srikar@linux.vnet.ibm.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2] ptrace: fix set_task_blockstep()->update_debugctlmsr() logic
Date: Fri, 3 Aug 2012 19:38:30 +0200 [thread overview]
Message-ID: <20120803173830.GA22687@redhat.com> (raw)
In-Reply-To: <501BFF95.8040202@linutronix.de>
On 08/03, Sebastian Andrzej Siewior wrote:
>
> On 08/03/2012 06:29 PM, Oleg Nesterov wrote:
>> diff --git a/arch/x86/kernel/step.c b/arch/x86/kernel/step.c
>> index afa60db..636402e 100644
>> --- a/arch/x86/kernel/step.c
>> +++ b/arch/x86/kernel/step.c
>> @@ -166,12 +166,18 @@ static void set_task_blockstep(struct task_struct *task, bool on)
>> else
>> clear_tsk_thread_flag(task, TIF_BLOCKSTEP);
>>
>> + if (task != current)
>> + return;
>> +
>> + /* ensure irq/preemption can't change debugctl in between */
>> + local_irq_disable();
>> debugctl = get_debugctlmsr();
>> if (on)
>> debugctl |= DEBUGCTLMSR_BTF;
>> else
>> debugctl&= ~DEBUGCTLMSR_BTF;
>> update_debugctlmsr(debugctl);
>> + local_irq_enable();
>
> wouldn't preempt_disable() be enough?
preempt_disable() can't help if interrupt handler changes
other bits in between?
Oleg.
next prev parent reply other threads:[~2012-08-03 17:42 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-08-03 16:29 [PATCH 0/2] ptrace: DEBUGCTLMSR_BTF fixes Oleg Nesterov
2012-08-03 16:29 ` [PATCH 1/2] ptrace: introduce set_task_blockstep() helper Oleg Nesterov
2012-08-03 16:29 ` [PATCH 2/2] ptrace: fix set_task_blockstep()->update_debugctlmsr() logic Oleg Nesterov
2012-08-03 16:43 ` Sebastian Andrzej Siewior
2012-08-03 17:38 ` Oleg Nesterov [this message]
2012-08-03 18:28 ` Sebastian Andrzej Siewior
2012-08-07 15:13 ` Oleg Nesterov
2012-08-07 9:41 ` Sebastian Andrzej Siewior
2012-08-07 10:52 ` Sebastian Andrzej Siewior
2012-08-07 15:15 ` Oleg Nesterov
2012-08-07 15:29 ` Sebastian Andrzej Siewior
2012-08-07 15:31 ` Oleg Nesterov
2012-08-07 15:12 ` Oleg Nesterov
2012-08-06 16:14 ` [PATCH 0/2] ptrace: DEBUGCTLMSR_BTF fixes Sebastian Andrzej Siewior
2012-08-07 15:15 ` Oleg Nesterov
2012-08-07 15:38 ` Sebastian Andrzej Siewior
2012-08-07 15:46 ` Oleg Nesterov
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