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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,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 43B6CC5519F for ; Mon, 23 Nov 2020 02:25:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E9E822076B for ; Mon, 23 Nov 2020 02:25:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726964AbgKWCY4 (ORCPT ); Sun, 22 Nov 2020 21:24:56 -0500 Received: from foss.arm.com ([217.140.110.172]:51724 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726885AbgKWCY4 (ORCPT ); Sun, 22 Nov 2020 21:24:56 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id B37781042; Sun, 22 Nov 2020 18:24:55 -0800 (PST) Received: from e113632-lin.cambridge.arm.com (e113632-lin.cambridge.arm.com [10.1.194.46]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 650CC3F70D; Sun, 22 Nov 2020 18:24:54 -0800 (PST) From: Valentin Schneider To: linux-kernel@vger.kernel.org, x86@kernel.org Cc: James Morse , Fenghua Yu , Reinette Chatre , Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" Subject: [PATCH v2 1/3] x86/intel_rdt: Check monitor group vs control group membership earlier Date: Mon, 23 Nov 2020 02:24:31 +0000 Message-Id: <20201123022433.17905-2-valentin.schneider@arm.com> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20201123022433.17905-1-valentin.schneider@arm.com> References: <20201123022433.17905-1-valentin.schneider@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org A task can only be moved between monitor groups if both groups belong to the same control group. This is checked fairly late however: by that time we already have appended a task_work() callback, the execution of which will be useless (there are no closid/rmid updates to handle, barring concurrent writes). Check the validity of the move earlier to save any kzalloc() / task_work_add() if it wasn't going to be necessary. Reviewed-by: James Morse Signed-off-by: Valentin Schneider --- arch/x86/kernel/cpu/resctrl/rdtgroup.c | 21 +++++++++++++-------- 1 file changed, 13 insertions(+), 8 deletions(-) diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c index af323e2e3100..b6b5b95df833 100644 --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c @@ -581,12 +581,7 @@ static int __rdtgroup_move_task(struct task_struct *tsk, tsk->closid = rdtgrp->closid; tsk->rmid = rdtgrp->mon.rmid; } else if (rdtgrp->type == RDTMON_GROUP) { - if (rdtgrp->mon.parent->closid == tsk->closid) { - tsk->rmid = rdtgrp->mon.rmid; - } else { - rdt_last_cmd_puts("Can't move task to different control group\n"); - ret = -EINVAL; - } + tsk->rmid = rdtgrp->mon.rmid; } } return ret; @@ -673,9 +668,19 @@ static int rdtgroup_move_task(pid_t pid, struct rdtgroup *rdtgrp, rcu_read_unlock(); ret = rdtgroup_task_write_permission(tsk, of); - if (!ret) - ret = __rdtgroup_move_task(tsk, rdtgrp); + if (ret) + goto out; + if (rdtgrp->type == RDTMON_GROUP && + rdtgrp->mon.parent->closid != tsk->closid) { + rdt_last_cmd_puts("Can't move task to different control group\n"); + ret = -EINVAL; + goto out; + } + + ret = __rdtgroup_move_task(tsk, rdtgrp); + +out: put_task_struct(tsk); return ret; } -- 2.27.0