From patchwork Tue Jan 13 06:42:46 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jialing Fu X-Patchwork-Id: 5618201 Return-Path: X-Original-To: patchwork-linux-mmc@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork1.web.kernel.org (Postfix) with ESMTP id 611239F3A0 for ; Tue, 13 Jan 2015 06:42:11 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 7390720620 for ; Tue, 13 Jan 2015 06:42:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 63A1B20617 for ; Tue, 13 Jan 2015 06:42:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751610AbbAMGly (ORCPT ); Tue, 13 Jan 2015 01:41:54 -0500 Received: from mx0a-0016f401.pphosted.com ([67.231.148.174]:64065 "EHLO mx0a-0016f401.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751557AbbAMGlw (ORCPT ); Tue, 13 Jan 2015 01:41:52 -0500 Received: from pps.filterd (m0045849.ppops.net [127.0.0.1]) by mx0a-0016f401.pphosted.com (8.14.5/8.14.5) with SMTP id t0D6ZGO7027098; Mon, 12 Jan 2015 22:41:48 -0800 Received: from pps.reinject (localhost [127.0.0.1]) by mx0a-0016f401.pphosted.com with ESMTP id 1rubhvwqsh-1 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NOT); Mon, 12 Jan 2015 22:41:48 -0800 Received: from m0045849.ppops.net (m0045849.ppops.net [127.0.0.1]) by pps.reinject (8.14.5/8.14.5) with SMTP id t0D6b4Qm027970; Mon, 12 Jan 2015 22:41:47 -0800 Received: from sc-owa04.marvell.com ([199.233.58.150]) by mx0a-0016f401.pphosted.com with ESMTP id 1rubhvwqsg-1 (version=TLSv1/SSLv3 cipher=AES128-SHA bits=128 verify=NOT); Mon, 12 Jan 2015 22:41:47 -0800 Received: from maili.marvell.com (10.93.76.43) by sc-owa02.marvell.com (10.93.76.33) with Microsoft SMTP Server id 8.3.327.1; Mon, 12 Jan 2015 22:41:47 -0800 Received: from localhost (unknown [10.38.37.9]) by maili.marvell.com (Postfix) with ESMTP id E35FE3F703F; Mon, 12 Jan 2015 22:41:46 -0800 (PST) From: Jialing Fu To: Chris Ball , Ulf Hansson , , , Konstantin Dorfman , Seungwon Jeon CC: Jialing Fu Subject: [PATCH] mmc: core: fix race condition in mmc_wait_data_done Date: Tue, 13 Jan 2015 14:42:46 +0800 Message-ID: <1421131366-29685-1-git-send-email-jlfu@marvell.com> X-Mailer: git-send-email 1.9.1 MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:5.13.68, 1.0.33, 0.0.0000 definitions=2015-01-13_03:2015-01-12, 2015-01-13, 1970-01-01 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=7.0.1-1402240000 definitions=main-1501130070 Sender: linux-mmc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-mmc@vger.kernel.org X-Spam-Status: No, score=-6.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, T_RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP The following panic is captured in ker3.14, but the issue still exists in latest kernel. --------------------------------------------------------------------- [ 20.738217] c0 3136 (Compiler) Unable to handle kernel NULL pointer dereference at virtual address 00000578 ...... [ 20.738499] c0 3136 (Compiler) PC is at _raw_spin_lock_irqsave+0x24/0x60 [ 20.738527] c0 3136 (Compiler) LR is at _raw_spin_lock_irqsave+0x20/0x60 [ 20.740134] c0 3136 (Compiler) Call trace: [ 20.740165] c0 3136 (Compiler) [] _raw_spin_lock_irqsave+0x24/0x60 [ 20.740200] c0 3136 (Compiler) [] __wake_up+0x1c/0x54 [ 20.740230] c0 3136 (Compiler) [] mmc_wait_data_done+0x28/0x34 [ 20.740262] c0 3136 (Compiler) [] mmc_request_done+0xa4/0x220 [ 20.740314] c0 3136 (Compiler) [] sdhci_tasklet_finish+0xac/0x264 [ 20.740352] c0 3136 (Compiler) [] tasklet_action+0xa0/0x158 [ 20.740382] c0 3136 (Compiler) [] __do_softirq+0x10c/0x2e4 [ 20.740411] c0 3136 (Compiler) [] irq_exit+0x8c/0xc0 [ 20.740439] c0 3136 (Compiler) [] handle_IRQ+0x48/0xac [ 20.740469] c0 3136 (Compiler) [] gic_handle_irq+0x38/0x7c ---------------------------------------------------------------------- Because in SMP, "mrq" has race condition between below two paths: path1: CPU0: static void mmc_wait_data_done(struct mmc_request *mrq) { mrq->host->context_info.is_done_rcv = true; // // If CPU0 has just finished "is_done_rcv = true" in path1, and at // this moment, IRQ or ICache line missing happens in CPU0. // What happens in CPU1 (path2)? // // If the mmcqd thread in CPU1(path2) hasn't entered to sleep mode: // path2 would have chance to break from wait_event_interruptible // in mmc_wait_for_data_req_done and continue to run for next // mmc_request (mmc_blk_rw_rq_prep). // // Within mmc_blk_rq_prep, mrq is cleared to 0. // If below line still gets host from "mrq" as the result of // compiler, the panic happens as we traced. wake_up_interruptible(&mrq->host->context_info.wait); } path2: CPU1: static int mmc_wait_for_data_req_done(... { ... while (1) { wait_event_interruptible(context_info->wait, (context_info->is_done_rcv || context_info->is_new_req)); static void mmc_blk_rw_rq_prep(... { ... memset(brq, 0, sizeof(struct mmc_blk_request)); This issue happens very coincidentally; however adding mdelay(1) in mmc_wait_data_done as below could duplicate it easily. static void mmc_wait_data_done(struct mmc_request *mrq) { mrq->host->context_info.is_done_rcv = true; mdelay(1); wake_up_interruptible(&mrq->host->context_info.wait); } At runtime, IRQ or ICache line missing may just happen at the same place of the mdelay(1). This patch gets the mmc_context_info at the beginning of function, it can avoid this race condition. Signed-off-by: Jialing Fu --- drivers/mmc/core/core.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c index 9584bff..f08c9a8 100644 --- a/drivers/mmc/core/core.c +++ b/drivers/mmc/core/core.c @@ -326,8 +326,10 @@ EXPORT_SYMBOL(mmc_start_bkops); */ static void mmc_wait_data_done(struct mmc_request *mrq) { - mrq->host->context_info.is_done_rcv = true; - wake_up_interruptible(&mrq->host->context_info.wait); + struct mmc_context_info *context_info = &mrq->host->context_info; + + context_info->is_done_rcv = true; + wake_up_interruptible(&context_info->wait); } static void mmc_wait_done(struct mmc_request *mrq)