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=-3.9 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED 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 115B9C65BAF for ; Sun, 9 Dec 2018 22:04:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D40C320661 for ; Sun, 9 Dec 2018 22:04:13 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D40C320661 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=decadent.org.uk Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726705AbeLIWEM (ORCPT ); Sun, 9 Dec 2018 17:04:12 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:35790 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726639AbeLIVza (ORCPT ); Sun, 9 Dec 2018 16:55:30 -0500 Received: from pub.yeoldevic.com ([81.174.156.145] helo=deadeye) by shadbolt.decadent.org.uk with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1gW72t-0002ij-Qo; Sun, 09 Dec 2018 21:55:28 +0000 Received: from ben by deadeye with local (Exim 4.91) (envelope-from ) id 1gW72k-0003do-94; Sun, 09 Dec 2018 21:55:18 +0000 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Jiri Olsa" , "Peter Zijlstra" , "Alexander Shishkin" , "Ingo Molnar" , "Vince Weaver" , "Linus Torvalds" , "Stephane Eranian" , "Arnaldo Carvalho de Melo" , "Thomas Gleixner" Date: Sun, 09 Dec 2018 21:50:33 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) X-Patchwork-Hint: ignore Subject: [PATCH 3.16 288/328] perf/core: Fix perf_pmu_unregister() locking In-Reply-To: X-SA-Exim-Connect-IP: 81.174.156.145 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.62-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Peter Zijlstra commit a9f9772114c8b07ae75bcb3654bd017461248095 upstream. When we unregister a PMU, we fail to serialize the @pmu_idr properly. Fix that by doing the entire thing under pmu_lock. Signed-off-by: Peter Zijlstra (Intel) Cc: Alexander Shishkin Cc: Arnaldo Carvalho de Melo Cc: Jiri Olsa Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Stephane Eranian Cc: Thomas Gleixner Cc: Vince Weaver Fixes: 2e80a82a49c4 ("perf: Dynamic pmu types") Signed-off-by: Ingo Molnar [bwh: Backported to 3.16: - Also remove "out" label in free_pmu_context() - Adjust context] Signed-off-by: Ben Hutchings --- --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -6705,20 +6705,17 @@ static void free_pmu_context(struct pmu { struct pmu *i; - mutex_lock(&pmus_lock); /* * Like a real lame refcount. */ list_for_each_entry(i, &pmus, entry) { if (i->pmu_cpu_context == pmu->pmu_cpu_context) { update_pmu_context(i, pmu); - goto out; + return; } } free_percpu(pmu->pmu_cpu_context); -out: - mutex_unlock(&pmus_lock); } static struct idr pmu_idr; @@ -6930,12 +6927,8 @@ EXPORT_SYMBOL_GPL(perf_pmu_register); void perf_pmu_unregister(struct pmu *pmu) { - int remove_device; - mutex_lock(&pmus_lock); - remove_device = pmu_bus_running; list_del_rcu(&pmu->entry); - mutex_unlock(&pmus_lock); /* * We dereference the pmu list under both SRCU and regular RCU, so @@ -6947,11 +6940,12 @@ void perf_pmu_unregister(struct pmu *pmu free_percpu(pmu->pmu_disable_count); if (pmu->type >= PERF_TYPE_MAX) idr_remove(&pmu_idr, pmu->type); - if (remove_device) { + if (pmu_bus_running) { device_del(pmu->dev); put_device(pmu->dev); } free_pmu_context(pmu); + mutex_unlock(&pmus_lock); } EXPORT_SYMBOL_GPL(perf_pmu_unregister);