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=-19.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT autolearn=unavailable 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 5BEF8C6379B for ; Thu, 15 Jul 2021 19:28:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 541286141A for ; Thu, 15 Jul 2021 19:28:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344941AbhGOTah (ORCPT ); Thu, 15 Jul 2021 15:30:37 -0400 Received: from mail.kernel.org ([198.145.29.99]:49976 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S244048AbhGOTKg (ORCPT ); Thu, 15 Jul 2021 15:10:36 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 282EE613D1; Thu, 15 Jul 2021 19:07:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1626376061; bh=+DqxFN9ITQT8/uYsw9hTN5wttBWimqS6cfsrA3DFqjI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=rIZ8WWXHFL7iR2/8GJnWUpKh7tWyAD7NVuaTKf78QwHq81DlxYo+L/9l7qK8Mihn9 bABBDlwbJX/XrpTYlNojfx0gF5iiXxfFuHvZm3bG4rMs7ngOEk429oiK9oi1JLw1f7 i4A6FS78w3VepJEAZBvQNMNJmaJglqlgQT7v7pjY= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Radim Pavlik , Linus Walleij , Sasha Levin Subject: [PATCH 5.13 073/266] pinctrl: mcp23s08: fix race condition in irq handler Date: Thu, 15 Jul 2021 20:37:08 +0200 Message-Id: <20210715182627.048814039@linuxfoundation.org> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210715182613.933608881@linuxfoundation.org> References: <20210715182613.933608881@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Radim Pavlik [ Upstream commit 897120d41e7afd9da435cb00041a142aeeb53c07 ] Checking value of MCP_INTF in mcp23s08_irq suggests that the handler may be called even when there is no interrupt pending. But the actual interrupt could happened between reading MCP_INTF and MCP_GPIO. In this situation we got nothing from MCP_INTF, but the event gets acknowledged on the expander by reading MCP_GPIO. This leads to losing events. Fix the problem by not reading any register until we see something in MCP_INTF. The error was reproduced and fix tested on MCP23017. Signed-off-by: Radim Pavlik Link: https://lore.kernel.org/r/AM7PR06MB6769E1183F68DEBB252F665ABA3E9@AM7PR06MB6769.eurprd06.prod.outlook.com Signed-off-by: Linus Walleij Signed-off-by: Sasha Levin --- drivers/pinctrl/pinctrl-mcp23s08.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/drivers/pinctrl/pinctrl-mcp23s08.c b/drivers/pinctrl/pinctrl-mcp23s08.c index ce2d8014b7e0..799d596a1a4b 100644 --- a/drivers/pinctrl/pinctrl-mcp23s08.c +++ b/drivers/pinctrl/pinctrl-mcp23s08.c @@ -351,6 +351,11 @@ static irqreturn_t mcp23s08_irq(int irq, void *data) if (mcp_read(mcp, MCP_INTF, &intf)) goto unlock; + if (intf == 0) { + /* There is no interrupt pending */ + return IRQ_HANDLED; + } + if (mcp_read(mcp, MCP_INTCAP, &intcap)) goto unlock; @@ -368,11 +373,6 @@ static irqreturn_t mcp23s08_irq(int irq, void *data) mcp->cached_gpio = gpio; mutex_unlock(&mcp->lock); - if (intf == 0) { - /* There is no interrupt pending */ - return IRQ_HANDLED; - } - dev_dbg(mcp->chip.parent, "intcap 0x%04X intf 0x%04X gpio_orig 0x%04X gpio 0x%04X\n", intcap, intf, gpio_orig, gpio); -- 2.30.2