From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751938AbdIUPVn convert rfc822-to-8bit (ORCPT ); Thu, 21 Sep 2017 11:21:43 -0400 Received: from Galois.linutronix.de ([146.0.238.70]:36325 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751675AbdIUPVm (ORCPT ); Thu, 21 Sep 2017 11:21:42 -0400 Date: Thu, 21 Sep 2017 17:21:40 +0200 From: Sebastian Andrzej Siewior To: Joerg Roedel Cc: iommu@lists.linux-foundation.org, vinadhy@gmail.com, linux-kernel@vger.kernel.org Subject: [PATCH v2] iommu/iova: Use raw_cpu_ptr() instead of get_cpu_ptr() for ->fq Message-ID: <20170921152140.grayy3a7ok2im7xa@linutronix.de> References: <20170906103459.oi2nn7jondjqdo5m@linutronix.de> <20170919094119.bibxslqyeefbx7gf@8bytes.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8BIT In-Reply-To: <20170919094119.bibxslqyeefbx7gf@8bytes.org> User-Agent: NeoMutt/20170609 (1.8.3) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org get_cpu_ptr() disabled preemption and returns the ->fq object of the current CPU. raw_cpu_ptr() does the same except that it not disable preemption which means the scheduler can move it to another CPU after it obtained the per-CPU object. In this case this is not bad because the data structure itself is protected with a spin_lock. This change shouldn't matter however on RT it does because the sleeping lock can't be accessed with disabled preemption. Cc: Joerg Roedel Cc: iommu@lists.linux-foundation.org Reported-by: vinadhy@gmail.com Signed-off-by: Sebastian Andrzej Siewior --- On 2017-09-19 11:41:19 [+0200], Joerg Roedel wrote: > Hi Sebastian, Hi Jörg, > I moved the flushing to driver/iommu/iova.c to share it with the Intel > IOMMU and possibly other drivers too, so this patch does no longer apply > to v4.14-rc1. Can you update the patch to these changes? Sure. v1…v2: move the change from amd_iommu.c to iova.c drivers/iommu/iova.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) diff --git a/drivers/iommu/iova.c b/drivers/iommu/iova.c index 33edfa794ae9..b30900025c62 100644 --- a/drivers/iommu/iova.c +++ b/drivers/iommu/iova.c @@ -570,7 +570,7 @@ void queue_iova(struct iova_domain *iovad, unsigned long pfn, unsigned long pages, unsigned long data) { - struct iova_fq *fq = get_cpu_ptr(iovad->fq); + struct iova_fq *fq = raw_cpu_ptr(iovad->fq); unsigned long flags; unsigned idx; @@ -600,8 +600,6 @@ void queue_iova(struct iova_domain *iovad, if (atomic_cmpxchg(&iovad->fq_timer_on, 0, 1) == 0) mod_timer(&iovad->fq_timer, jiffies + msecs_to_jiffies(IOVA_FQ_TIMEOUT)); - - put_cpu_ptr(iovad->fq); } EXPORT_SYMBOL_GPL(queue_iova); -- 2.14.1