From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751699AbdF1K0k (ORCPT ); Wed, 28 Jun 2017 06:26:40 -0400 Received: from 8bytes.org ([81.169.241.247]:47708 "EHLO theia.8bytes.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751613AbdF1K0d (ORCPT ); Wed, 28 Jun 2017 06:26:33 -0400 Date: Wed, 28 Jun 2017 12:26:25 +0200 From: Joerg Roedel To: Sebastian Andrzej Siewior Cc: tglx@linutronix.de, linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, Andrew Morton Subject: Re: [PATCH 2/3] iommu/iova: don't disable preempt around this_cpu_ptr() Message-ID: <20170628102625.GJ14532@8bytes.org> References: <20170627161648.30302-1-bigeasy@linutronix.de> <20170627161648.30302-2-bigeasy@linutronix.de> <20170628092205.GB30388@8bytes.org> <20170628093154.ncrcvwretfcoizx3@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170628093154.ncrcvwretfcoizx3@linutronix.de> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jun 28, 2017 at 11:31:55AM +0200, Sebastian Andrzej Siewior wrote: > It really does. The spin_lock() does disable preemption but this is not > the problem. The thing is that the preempt_disable() is superfluous and > it hurts Preempt-RT (and this is how I noticed it). Also the > get_cpu_ptr() is not requited and was only added to keep lockdep quiet > (according to the history). > Everything else here can stay as-is, I am just asking for the removal of > the redundant preempt_disable() where it is not required. Okay, makes sense, I applied both patches. Thanks, Joerg