From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E8E59C04AAC for ; Mon, 20 May 2019 13:43:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BF3E820856 for ; Mon, 20 May 2019 13:43:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389354AbfETNnM (ORCPT ); Mon, 20 May 2019 09:43:12 -0400 Received: from mga07.intel.com ([134.134.136.100]:25194 "EHLO mga07.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388106AbfETNnL (ORCPT ); Mon, 20 May 2019 09:43:11 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga004.jf.intel.com ([10.7.209.38]) by orsmga105.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 20 May 2019 06:43:11 -0700 X-ExtLoop1: 1 Received: from gklab-127-091.igk.intel.com (HELO gklab-125-020.igk.intel.com) ([10.91.125.20]) by orsmga004.jf.intel.com with ESMTP; 20 May 2019 06:43:09 -0700 From: Lukasz Odzioba To: linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org Cc: dwmw2@infradead.org, joro@8bytes.org, lukasz.odzioba@intel.com, grzegorz.andrejczuk@intel.com Subject: [PATCH 1/1] iommu/vt-d: Remove unnecessary rcu_read_locks Date: Mon, 20 May 2019 15:41:28 +0200 Message-Id: <1558359688-21804-1-git-send-email-lukasz.odzioba@intel.com> X-Mailer: git-send-email 1.8.3.1 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org We use RCU's for rarely updated lists like iommus, rmrr, atsr units. I'm not sure why domain_remove_dev_info() in domain_exit() was surrounded by rcu_read_lock. Lock was present before refactoring in d160aca527, but it was related to rcu list, not domain_remove_dev_info function. dmar_remove_one_dev_info() doesn't touch any of those lists, so it doesn't require a lock. In fact it is called 6 times without it anyway. Fixes: d160aca5276d ("iommu/vt-d: Unify domain->iommu attach/detachment") Signed-off-by: Lukasz Odzioba --- drivers/iommu/intel-iommu.c | 4 ---- 1 file changed, 4 deletions(-) diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c index a209199..1b7ad80 100644 --- a/drivers/iommu/intel-iommu.c +++ b/drivers/iommu/intel-iommu.c @@ -1911,9 +1911,7 @@ static void domain_exit(struct dmar_domain *domain) struct page *freelist; /* Remove associated devices and clear attached or cached domains */ - rcu_read_lock(); domain_remove_dev_info(domain); - rcu_read_unlock(); /* destroy iovas */ put_iova_domain(&domain->iovad); @@ -5254,9 +5252,7 @@ static int intel_iommu_attach_device(struct iommu_domain *domain, old_domain = find_domain(dev); if (old_domain) { - rcu_read_lock(); dmar_remove_one_dev_info(dev); - rcu_read_unlock(); if (!domain_type_is_vm_or_si(old_domain) && list_empty(&old_domain->devices)) -- 1.8.3.1