From patchwork Tue Apr 2 16:44:33 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Farhan Ali X-Patchwork-Id: 10882105 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 357251575 for ; Tue, 2 Apr 2019 16:44:45 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 20BE526E78 for ; Tue, 2 Apr 2019 16:44:45 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 149BF27E63; Tue, 2 Apr 2019 16:44:45 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id A348B26E78 for ; Tue, 2 Apr 2019 16:44:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729527AbfDBQon (ORCPT ); Tue, 2 Apr 2019 12:44:43 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:45508 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727460AbfDBQon (ORCPT ); Tue, 2 Apr 2019 12:44:43 -0400 Received: from pps.filterd (m0098417.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id x32GW2jb090267 for ; Tue, 2 Apr 2019 12:44:41 -0400 Received: from e11.ny.us.ibm.com (e11.ny.us.ibm.com [129.33.205.201]) by mx0a-001b2d01.pphosted.com with ESMTP id 2rmauuacna-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Tue, 02 Apr 2019 12:44:41 -0400 Received: from localhost by e11.ny.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Tue, 2 Apr 2019 17:44:38 +0100 Received: from b01ledav003.gho.pok.ibm.com (b01ledav003.gho.pok.ibm.com [9.57.199.108]) by b01cxnp23033.gho.pok.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x32GibAv21364822 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 2 Apr 2019 16:44:37 GMT Received: from b01ledav003.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 2C925B2066; Tue, 2 Apr 2019 16:44:37 +0000 (GMT) Received: from b01ledav003.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 1E643B2064; Tue, 2 Apr 2019 16:44:37 +0000 (GMT) Received: from alifm-ThinkPad-T470p.pok.ibm.com (unknown [9.56.58.129]) by b01ledav003.gho.pok.ibm.com (Postfix) with ESMTPS; Tue, 2 Apr 2019 16:44:37 +0000 (GMT) From: Farhan Ali To: kvm@vger.kernel.org, linux-s390@vger.kernel.org Cc: farman@linux.ibm.com, cohuck@redhat.com, pasic@linux.ibm.com, pmorel@linux.ibm.com, alifm@linux.ibm.com Subject: [RFC v1 1/3] vfio-ccw: Do not call flush_workqueue while holding the spinlock Date: Tue, 2 Apr 2019 12:44:33 -0400 X-Mailer: git-send-email 2.7.4 In-Reply-To: References: In-Reply-To: References: X-TM-AS-GCONF: 00 x-cbid: 19040216-2213-0000-0000-0000036F7CCD X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00010862; HX=3.00000242; KW=3.00000007; PH=3.00000004; SC=3.00000284; SDB=6.01183329; UDB=6.00619504; IPR=6.00964077; MB=3.00026263; MTD=3.00000008; XFM=3.00000015; UTC=2019-04-02 16:44:39 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19040216-2214-0000-0000-00005DE0C90E Message-Id: <08af324a0065aa4311de58d6ac9bd7b69ad6143e.1554222348.git.alifm@linux.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-04-02_06:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=684 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1904020110 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Currently we call flush_workqueue while holding the subchannel spinlock. But flush_workqueue function can go to sleep, so do not call the function while holding the spinlock. Fixes the following bug: [ 285.203430] BUG: scheduling while atomic: bash/14193/0x00000002 [ 285.203434] INFO: lockdep is turned off. .... [ 285.203485] Preemption disabled at: [ 285.203488] [<000003ff80243e5c>] vfio_ccw_sch_quiesce+0xbc/0x120 [vfio_ccw] [ 285.203496] CPU: 7 PID: 14193 Comm: bash Tainted: G W .... [ 285.203504] Call Trace: [ 285.203510] ([<0000000000113772>] show_stack+0x82/0xd0) [ 285.203514] [<0000000000b7a102>] dump_stack+0x92/0xd0 [ 285.203518] [<000000000017b8be>] __schedule_bug+0xde/0xf8 [ 285.203524] [<0000000000b95b5a>] __schedule+0x7a/0xc38 [ 285.203528] [<0000000000b9678a>] schedule+0x72/0xb0 [ 285.203533] [<0000000000b9bfbc>] schedule_timeout+0x34/0x528 [ 285.203538] [<0000000000b97608>] wait_for_common+0x118/0x1b0 [ 285.203544] [<0000000000166d6a>] flush_workqueue+0x182/0x548 [ 285.203550] [<000003ff80243e6e>] vfio_ccw_sch_quiesce+0xce/0x120 [vfio_ccw] [ 285.203556] [<000003ff80245278>] vfio_ccw_mdev_reset+0x38/0x70 [vfio_ccw] [ 285.203562] [<000003ff802458b0>] vfio_ccw_mdev_remove+0x40/0x78 [vfio_ccw] [ 285.203567] [<000003ff801a499c>] mdev_device_remove_ops+0x3c/0x80 [mdev] [ 285.203573] [<000003ff801a4d5c>] mdev_device_remove+0xc4/0x130 [mdev] [ 285.203578] [<000003ff801a5074>] remove_store+0x6c/0xa8 [mdev] [ 285.203582] [<000000000046f494>] kernfs_fop_write+0x14c/0x1f8 [ 285.203588] [<00000000003c1530>] __vfs_write+0x38/0x1a8 [ 285.203593] [<00000000003c187c>] vfs_write+0xb4/0x198 [ 285.203597] [<00000000003c1af2>] ksys_write+0x5a/0xb0 [ 285.203601] [<0000000000b9e270>] system_call+0xdc/0x2d8 Signed-off-by: Farhan Ali Reviewed-by: Eric Farman Reviewed-by: Pierre Morel --- drivers/s390/cio/vfio_ccw_drv.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/s390/cio/vfio_ccw_drv.c b/drivers/s390/cio/vfio_ccw_drv.c index 8f06125..5aca475 100644 --- a/drivers/s390/cio/vfio_ccw_drv.c +++ b/drivers/s390/cio/vfio_ccw_drv.c @@ -57,9 +57,9 @@ int vfio_ccw_sch_quiesce(struct subchannel *sch) wait_for_completion_timeout(&completion, 3*HZ); - spin_lock_irq(sch->lock); private->completion = NULL; flush_workqueue(vfio_ccw_work_q); + spin_lock_irq(sch->lock); ret = cio_cancel_halt_clear(sch, &iretry); };