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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 018BFC4167B for ; Mon, 15 Nov 2021 23:11:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DDCB061929 for ; Mon, 15 Nov 2021 23:11:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1352498AbhKOXNx (ORCPT ); Mon, 15 Nov 2021 18:13:53 -0500 Received: from mail.kernel.org ([198.145.29.99]:38250 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S243400AbhKOTHc (ORCPT ); Mon, 15 Nov 2021 14:07:32 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id AD80E633F4; Mon, 15 Nov 2021 18:17:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1637000235; bh=CdI08ViV6BvG1YXh6LB3amNdngiUBTB8LPRQeIAyfvg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=nxVBiAeiGzpE6m5U9loZEcZNYW9oW1D7RahxMl3tCqPoiynxivVQ++FQ9wh/Di5AO sCVyBSaz5YLHrRlwul2BL5l9dLBj9LpF1yOkOGhBuQRCe1895mN0tDlOLJAj89Jbhl uruppo2StClKMqWT6hcXhLj5ki6nB+1PBDF31O/E= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Sumit Saxena , "Martin K. Petersen" , Sasha Levin Subject: [PATCH 5.14 586/849] scsi: megaraid_sas: Fix concurrent access to ISR between IRQ polling and real interrupt Date: Mon, 15 Nov 2021 18:01:09 +0100 Message-Id: <20211115165440.075540650@linuxfoundation.org> X-Mailer: git-send-email 2.33.1 In-Reply-To: <20211115165419.961798833@linuxfoundation.org> References: <20211115165419.961798833@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: Sumit Saxena [ Upstream commit e7dcc514a49e74051b869697d5ab0370f6301d57 ] IRQ polling thread calls ISR after enable_irq() to handle any missed I/O completion. The atomic flag "in_used" was added to have the synchronization between the IRQ polling thread and the interrupt context. There is a bug around it leading to a race condition. Below is the sequence: - IRQ polling thread accesses ISR, fetches the reply descriptor. - Real interrupt arrives and pre-empts polling thread (enable_irq() is already called). - Interrupt context picks the same reply descriptor as fetched by polling thread, processes it, and exits. - Polling thread resumes and processes the descriptor which is already processed by interrupt thread leads to kernel crash. Setting the "in_used" flag before fetching the reply descriptor ensures synchronized access to ISR. Link: https://www.spinics.net/lists/linux-scsi/msg159440.html Link: https://lore.kernel.org/r/20210929124022.24605-2-sumit.saxena@broadcom.com Fixes: 9bedd36e9146 ("scsi: megaraid_sas: Handle missing interrupts while re-enabling IRQs") Signed-off-by: Sumit Saxena Signed-off-by: Martin K. Petersen Signed-off-by: Sasha Levin --- drivers/scsi/megaraid/megaraid_sas_fusion.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/drivers/scsi/megaraid/megaraid_sas_fusion.c b/drivers/scsi/megaraid/megaraid_sas_fusion.c index 06399c026a8d5..1ff2198583a71 100644 --- a/drivers/scsi/megaraid/megaraid_sas_fusion.c +++ b/drivers/scsi/megaraid/megaraid_sas_fusion.c @@ -3530,6 +3530,9 @@ complete_cmd_fusion(struct megasas_instance *instance, u32 MSIxIndex, if (atomic_read(&instance->adprecovery) == MEGASAS_HW_CRITICAL_ERROR) return IRQ_HANDLED; + if (irq_context && !atomic_add_unless(&irq_context->in_used, 1, 1)) + return 0; + desc = fusion->reply_frames_desc[MSIxIndex] + fusion->last_reply_idx[MSIxIndex]; @@ -3540,11 +3543,11 @@ complete_cmd_fusion(struct megasas_instance *instance, u32 MSIxIndex, reply_descript_type = reply_desc->ReplyFlags & MPI2_RPY_DESCRIPT_FLAGS_TYPE_MASK; - if (reply_descript_type == MPI2_RPY_DESCRIPT_FLAGS_UNUSED) + if (reply_descript_type == MPI2_RPY_DESCRIPT_FLAGS_UNUSED) { + if (irq_context) + atomic_dec(&irq_context->in_used); return IRQ_NONE; - - if (irq_context && !atomic_add_unless(&irq_context->in_used, 1, 1)) - return 0; + } num_completed = 0; -- 2.33.0