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=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS 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 0DDA4C43603 for ; Mon, 16 Dec 2019 11:16:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DCFD72082E for ; Mon, 16 Dec 2019 11:16:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727089AbfLPLQN (ORCPT ); Mon, 16 Dec 2019 06:16:13 -0500 Received: from cloudserver094114.home.pl ([79.96.170.134]:46034 "EHLO cloudserver094114.home.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727059AbfLPLQN (ORCPT ); Mon, 16 Dec 2019 06:16:13 -0500 Received: from 79.184.253.1.ipv4.supernova.orange.pl (79.184.253.1) (HELO kreacher.localnet) by serwer1319399.home.pl (79.96.170.134) with SMTP (IdeaSmtpServer 0.83.320) id 038a9e5e7a342150; Mon, 16 Dec 2019 12:16:11 +0100 From: "Rafael J. Wysocki" To: kc27041980@gmail.com Cc: Len Brown , linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/1] acpi/ec.c: Move call to kref_get() to under the mutex_lock(&ec->mutex) Date: Mon, 16 Dec 2019 12:16:10 +0100 Message-ID: <71678431.1RUZMxPmvT@kreacher> In-Reply-To: <1574679798-18958-1-git-send-email-KC17041980@gmail.com> References: <1574679798-18958-1-git-send-email-KC17041980@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Sender: linux-acpi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-acpi@vger.kernel.org On Monday, November 25, 2019 12:03:18 PM CET kc27041980@gmail.com wrote: > From: KC27041980 > > Move call to kref_get() to under the mutex_lock(&ec->mutex) as this > will remove any delete race scenarios. > > Signed-off-by: KC27041980 > --- > drivers/acpi/ec.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/drivers/acpi/ec.c b/drivers/acpi/ec.c > index da1e5c5..9c1bd57 100644 > --- a/drivers/acpi/ec.c > +++ b/drivers/acpi/ec.c > @@ -1073,8 +1073,12 @@ acpi_ec_get_query_handler_by_value(struct acpi_ec *ec, u8 value) > break; > } > } > + > + if (found) > + acpi_ec_get_query_handler(handler); > mutex_unlock(&ec->mutex); > - return found ? acpi_ec_get_query_handler(handler) : NULL; > + > + return found ? handler : NULL; > } > > static void acpi_ec_query_handler_release(struct kref *kref) > Well, what about the appended patch instead? --- drivers/acpi/ec.c | 16 ++++------------ 1 file changed, 4 insertions(+), 12 deletions(-) Index: linux-pm/drivers/acpi/ec.c =================================================================== --- linux-pm.orig/drivers/acpi/ec.c +++ linux-pm/drivers/acpi/ec.c @@ -1053,28 +1053,20 @@ void acpi_ec_unblock_transactions(void) Event Management -------------------------------------------------------------------------- */ static struct acpi_ec_query_handler * -acpi_ec_get_query_handler(struct acpi_ec_query_handler *handler) -{ - if (handler) - kref_get(&handler->kref); - return handler; -} - -static struct acpi_ec_query_handler * acpi_ec_get_query_handler_by_value(struct acpi_ec *ec, u8 value) { struct acpi_ec_query_handler *handler; - bool found = false; mutex_lock(&ec->mutex); list_for_each_entry(handler, &ec->list, node) { if (value == handler->query_bit) { - found = true; - break; + kref_get(&handler->kref); + mutex_unlock(&ec->mutex); + return handler; } } mutex_unlock(&ec->mutex); - return found ? acpi_ec_get_query_handler(handler) : NULL; + return NULL; } static void acpi_ec_query_handler_release(struct kref *kref)