From patchwork Tue Jan 19 21:08:10 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alan Stern X-Patchwork-Id: 8064911 Return-Path: X-Original-To: patchwork-linux-scsi@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 6E3959F96D for ; Tue, 19 Jan 2016 21:08:15 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id C699D2054E for ; Tue, 19 Jan 2016 21:08:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F278A2054C for ; Tue, 19 Jan 2016 21:08:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933097AbcASVIN (ORCPT ); Tue, 19 Jan 2016 16:08:13 -0500 Received: from iolanthe.rowland.org ([192.131.102.54]:34802 "HELO iolanthe.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S932702AbcASVIL (ORCPT ); Tue, 19 Jan 2016 16:08:11 -0500 Received: (qmail 4433 invoked by uid 2102); 19 Jan 2016 16:08:10 -0500 Received: from localhost (sendmail-bs@127.0.0.1) by localhost with SMTP; 19 Jan 2016 16:08:10 -0500 Date: Tue, 19 Jan 2016 16:08:10 -0500 (EST) From: Alan Stern X-X-Sender: stern@iolanthe.rowland.org To: Paul Menzel cc: Erich Schubert , Ben Hutchings , SCSI development list , <801925@bugs.debian.org>, Alexandre Rossi Subject: Re: NULL pointer dereference: IP: [] sr_runtime_suspend+0xc/0x20 [sr_mod] In-Reply-To: <1453222373.3588.3.camel@giantmonkey.de> Message-ID: MIME-Version: 1.0 Sender: linux-scsi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org X-Spam-Status: No, score=-6.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, RP_MATCHES_RCVD, T_TVD_MIME_EPI, UNPARSEABLE_RELAY autolearn=ham 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 On Tue, 19 Jan 2016, Paul Menzel wrote: > Could you please attach the debugging patch. Hopefully Alexandre, Erich, > or I will have some spare time to build an image from it. Actually, this patch is an attempt at a fix. After looking more carefully at your log pictures, I realized what the problem must be. It's too bad nobody was able to capture a log where the error occurred in sr_runtime_suspend, though -- all the logs in the bug report show sd_runtime_resume. > Alan, thank you a lot for being so responsive and helpful! You're welcome. Alan Stern drivers/scsi/sd.c | 7 +++++-- drivers/scsi/sr.c | 4 ++++ 2 files changed, 9 insertions(+), 2 deletions(-) Index: usb-4.4/drivers/scsi/sd.c =================================================================== --- usb-4.4.orig/drivers/scsi/sd.c +++ usb-4.4/drivers/scsi/sd.c @@ -3275,8 +3275,8 @@ static int sd_suspend_common(struct devi struct scsi_disk *sdkp = dev_get_drvdata(dev); int ret = 0; - if (!sdkp) - return 0; /* this can happen */ + if (!sdkp) /* E.g.: runtime suspend following sd_remove() */ + return 0; if (sdkp->WCE && sdkp->media_present) { sd_printk(KERN_NOTICE, sdkp, "Synchronizing SCSI cache\n"); @@ -3315,6 +3315,9 @@ static int sd_resume(struct device *dev) { struct scsi_disk *sdkp = dev_get_drvdata(dev); + if (!sdkp) /* E.g.: runtime resume at the start of sd_probe() */ + return 0; + if (!sdkp->device->manage_start_stop) return 0; Index: usb-4.4/drivers/scsi/sr.c =================================================================== --- usb-4.4.orig/drivers/scsi/sr.c +++ usb-4.4/drivers/scsi/sr.c @@ -144,6 +144,9 @@ static int sr_runtime_suspend(struct dev { struct scsi_cd *cd = dev_get_drvdata(dev); + if (!cd) /* E.g.: runtime suspend following sr_remove() */ + return 0; + if (cd->media_present) return -EBUSY; else @@ -985,6 +988,7 @@ static int sr_remove(struct device *dev) scsi_autopm_get_device(cd->device); del_gendisk(cd->disk); + dev_set_drvdata(dev, NULL); mutex_lock(&sr_ref_mutex); kref_put(&cd->kref, sr_kref_release);