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=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED 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 83B00C71122 for ; Sun, 14 Oct 2018 15:46:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 55A2A20645 for ; Sun, 14 Oct 2018 15:46:25 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 55A2A20645 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=decadent.org.uk Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729588AbeJNX1q (ORCPT ); Sun, 14 Oct 2018 19:27:46 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:37212 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728141AbeJNX1q (ORCPT ); Sun, 14 Oct 2018 19:27:46 -0400 Received: from [2a02:8011:400e:2:cbab:f00:c93f:614] (helo=deadeye) by shadbolt.decadent.org.uk with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.84_2) (envelope-from ) id 1gBiM9-0004cJ-Fh; Sun, 14 Oct 2018 16:31:01 +0100 Received: from ben by deadeye with local (Exim 4.91) (envelope-from ) id 1gBiLQ-0000Gj-IP; Sun, 14 Oct 2018 16:30:16 +0100 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Alex Smith" , "Ulf Hansson" , "Mathieu Malaterre" Date: Sun, 14 Oct 2018 16:25:41 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 096/366] mmc: jz4740: Fix race condition in IRQ mask update In-Reply-To: X-SA-Exim-Connect-IP: 2a02:8011:400e:2:cbab:f00:c93f:614 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.60-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Alex Smith commit a04f0017c22453613d5f423326b190c61e3b4f98 upstream. A spinlock is held while updating the internal copy of the IRQ mask, but not while writing it to the actual IMASK register. After the lock is released, an IRQ can occur before the IMASK register is written. If handling this IRQ causes the mask to be changed, when the handler returns back to the middle of the first mask update, a stale value will be written to the mask register. If this causes an IRQ to become unmasked that cannot have its status cleared by writing a 1 to it in the IREG register, e.g. the SDIO IRQ, then we can end up stuck with the same IRQ repeatedly being fired but not handled. Normally the MMC IRQ handler attempts to clear any unexpected IRQs by writing IREG, but for those that cannot be cleared in this way then the IRQ will just repeatedly fire. This was resulting in lockups after a while of using Wi-Fi on the CI20 (GitHub issue #19). Resolve by holding the spinlock until after the IMASK register has been updated. Link: https://github.com/MIPS/CI20_linux/issues/19 Fixes: 61bfbdb85687 ("MMC: Add support for the controller on JZ4740 SoCs.") Tested-by: Mathieu Malaterre Signed-off-by: Alex Smith Signed-off-by: Ulf Hansson Signed-off-by: Ben Hutchings --- drivers/mmc/host/jz4740_mmc.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/drivers/mmc/host/jz4740_mmc.c +++ b/drivers/mmc/host/jz4740_mmc.c @@ -148,9 +148,9 @@ static void jz4740_mmc_set_irq_enabled(s host->irq_mask &= ~irq; else host->irq_mask |= irq; - spin_unlock_irqrestore(&host->lock, flags); writew(host->irq_mask, host->base + JZ_REG_MMC_IMASK); + spin_unlock_irqrestore(&host->lock, flags); } static void jz4740_mmc_clock_enable(struct jz4740_mmc_host *host,