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=-16.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,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 F2C9CC43463 for ; Fri, 18 Sep 2020 02:36:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B93D423770 for ; Fri, 18 Sep 2020 02:36:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1600396594; bh=qIP9i10QNuFUqr7AyrHXWpVLZ26hz3Lw/9iPGrad+d4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=YLGTAspOdfWtdmcIHs4kCPoSh8E5b4tf9lE15PysViKQTOG/zHLsCHEDySDHHIssw 4X2MpaoOFXm1Artzcx7WQybOBrRIh/7AbBRZLcNIU7zg5bY2mratgpRrDcsswu5sxc s6s1VohaqsiTsSUWEY6r36FYB/3Xc93xldXSC6WE= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730072AbgIRCgd (ORCPT ); Thu, 17 Sep 2020 22:36:33 -0400 Received: from mail.kernel.org ([198.145.29.99]:39598 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728401AbgIRCMw (ORCPT ); Thu, 17 Sep 2020 22:12:52 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 7F6392376E; Fri, 18 Sep 2020 02:12:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1600395172; bh=qIP9i10QNuFUqr7AyrHXWpVLZ26hz3Lw/9iPGrad+d4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=HEeQLdSv0TNtTiVT5PSISJ6ZkmGDliGvOLvgZrfUJLO2YvQYQ2ni6Gl1aq2yiv5Ja 9tScd+E3uNFl1u2gdGBFHZvqRGSsNC1IOIKTh5nK5hS9El8bUXs0RDnWaacBcPFW+P Udzx2ai05CsEEdX4v6duFL9pzXZqj+BoDA1Xg2io= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: "Rafael J. Wysocki" , Sasha Levin , linux-acpi@vger.kernel.org Subject: [PATCH AUTOSEL 4.14 028/127] ACPI: EC: Reference count query handlers under lock Date: Thu, 17 Sep 2020 22:10:41 -0400 Message-Id: <20200918021220.2066485-28-sashal@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200918021220.2066485-1-sashal@kernel.org> References: <20200918021220.2066485-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "Rafael J. Wysocki" [ Upstream commit 3df663a147fe077a6ee8444ec626738946e65547 ] There is a race condition in acpi_ec_get_query_handler() theoretically allowing query handlers to go away before refernce counting them. In order to avoid it, call kref_get() on query handlers under ec->mutex. Also simplify the code a bit while at it. Signed-off-by: Rafael J. Wysocki Signed-off-by: Sasha Levin --- drivers/acpi/ec.c | 16 ++++------------ 1 file changed, 4 insertions(+), 12 deletions(-) diff --git a/drivers/acpi/ec.c b/drivers/acpi/ec.c index ebfc06f29f7b2..37aacb39e6922 100644 --- a/drivers/acpi/ec.c +++ b/drivers/acpi/ec.c @@ -1062,29 +1062,21 @@ 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) -- 2.25.1