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=-20.2 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 39424C636C9 for ; Mon, 19 Jul 2021 16:26:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 262916128A for ; Mon, 19 Jul 2021 16:26:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1349678AbhGSPpS (ORCPT ); Mon, 19 Jul 2021 11:45:18 -0400 Received: from mail.kernel.org ([198.145.29.99]:52608 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1343995AbhGSO70 (ORCPT ); Mon, 19 Jul 2021 10:59:26 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 57EF761355; Mon, 19 Jul 2021 15:38:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1626709086; bh=rz6HuaKLWeUglRhVWMbMuuqcGoxkJpO71ZRphdknjdA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=niAHtNgUcPZeEYW3GFrMYhPi1FIFCzy3wPcFMDhywA0cTnFZ5iihiLy+pP1id4AR6 Vz8AlvqiV3qBzUoYfZCF7s6JidRGedPlaol+uemTTumq+kUDQj7AG1B8zgn9kuOS5B D6tGWHhvjJi26ChqOKq/XSq5P+7VQoLd7on6cvzw= 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 4.19 246/421] pinctrl: mcp23s08: fix race condition in irq handler Date: Mon, 19 Jul 2021 16:50:57 +0200 Message-Id: <20210719144954.940636728@linuxfoundation.org> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210719144946.310399455@linuxfoundation.org> References: <20210719144946.310399455@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 5b5a4323ae63..f22999129269 100644 --- a/drivers/pinctrl/pinctrl-mcp23s08.c +++ b/drivers/pinctrl/pinctrl-mcp23s08.c @@ -458,6 +458,11 @@ 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; @@ -475,11 +480,6 @@ 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