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=-16.8 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 25FEAC11F7B for ; Tue, 6 Jul 2021 12:02:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1C2FE620DB for ; Tue, 6 Jul 2021 12:02:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243097AbhGFMDQ (ORCPT ); Tue, 6 Jul 2021 08:03:16 -0400 Received: from mail.kernel.org ([198.145.29.99]:47622 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237361AbhGFLgG (ORCPT ); Tue, 6 Jul 2021 07:36:06 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 852BC61D6A; Tue, 6 Jul 2021 11:27:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1625570827; bh=rz6HuaKLWeUglRhVWMbMuuqcGoxkJpO71ZRphdknjdA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Bif97AyVpmR8s26zNCYryq+DBBo3rIWU9kIpOtOsff6uPg6Ur+D/ANXWIDVMtQmgx K/56s4TpjdXAjPAF5EgNVw3er21isf46rwjyobUj78p8sPEW9R7I+Vd8buqV4ZvZi1 0B5vKPqxazsi1QWdaAV2u09O2QOwteXAvvmCpzIHMoVdfbi3xQKR5+ost7TIstt/BY LPO4cDJLHwx3HmVPtWJ0DUAQxGvHFV+A2v/8q4V7mwMEfk9G0iZiZVtKLJxszw5XYZ yy9gdpixGupZwDASBKYlVJJLRmuyxXkUF3QXnVPHeKl9cnK0OG8S6FTWhHvcCFQBCG NKGIMCXXNE6Eg== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Radim Pavlik , Linus Walleij , Sasha Levin , linux-gpio@vger.kernel.org Subject: [PATCH AUTOSEL 4.19 22/55] pinctrl: mcp23s08: fix race condition in irq handler Date: Tue, 6 Jul 2021 07:26:05 -0400 Message-Id: <20210706112638.2065023-22-sashal@kernel.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210706112638.2065023-1-sashal@kernel.org> References: <20210706112638.2065023-1-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: 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