From patchwork Wed Jan 22 07:43:02 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: EJ Hsu X-Patchwork-Id: 11345127 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 90E1E924 for ; Wed, 22 Jan 2020 07:43:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6F02D2465B for ; Wed, 22 Jan 2020 07:43:09 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=nvidia.com header.i=@nvidia.com header.b="K9yY6Mi8" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726135AbgAVHnI (ORCPT ); Wed, 22 Jan 2020 02:43:08 -0500 Received: from hqnvemgate26.nvidia.com ([216.228.121.65]:6742 "EHLO hqnvemgate26.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725946AbgAVHnI (ORCPT ); Wed, 22 Jan 2020 02:43:08 -0500 Received: from hqpgpgate101.nvidia.com (Not Verified[216.228.121.13]) by hqnvemgate26.nvidia.com (using TLS: TLSv1.2, DES-CBC3-SHA) id ; Tue, 21 Jan 2020 23:42:53 -0800 Received: from hqmail.nvidia.com ([172.20.161.6]) by hqpgpgate101.nvidia.com (PGP Universal service); Tue, 21 Jan 2020 23:43:07 -0800 X-PGP-Universal: processed; by hqpgpgate101.nvidia.com on Tue, 21 Jan 2020 23:43:07 -0800 Received: from HQMAIL101.nvidia.com (172.20.187.10) by HQMAIL111.nvidia.com (172.20.187.18) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Wed, 22 Jan 2020 07:43:07 +0000 Received: from rnnvemgw01.nvidia.com (10.128.109.123) by HQMAIL101.nvidia.com (172.20.187.10) with Microsoft SMTP Server (TLS) id 15.0.1473.3 via Frontend Transport; Wed, 22 Jan 2020 07:43:07 +0000 Received: from ubuntu.nvidia.com (Not Verified[10.19.108.185]) by rnnvemgw01.nvidia.com with Trustwave SEG (v7,5,8,10121) id ; Tue, 21 Jan 2020 23:43:06 -0800 From: EJ Hsu To: CC: , EJ Hsu Subject: [PATCH v2] usb: uas: fix a plug & unplug racing Date: Tue, 21 Jan 2020 23:43:02 -0800 Message-ID: <20200122074302.69790-1-ejh@nvidia.com> X-Mailer: git-send-email 2.17.1 X-NVConfidentiality: public MIME-Version: 1.0 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1579678973; bh=EejosBoVtPQeM/+EcX5Ey7GZh24ebR/LoRLXhP35S5E=; h=X-PGP-Universal:From:To:CC:Subject:Date:Message-ID:X-Mailer: X-NVConfidentiality:MIME-Version:Content-Type; b=K9yY6Mi8RA4sRBsVV5xzXecDym5K7PqkG2uG5mZV9qtqTOMIUhleNv126mZ7HQRrU 6HiZxuJK9qhPuhBRg1aXZCFUbkq1zL7BWI88Y8Sl5ZCGjAZQ/CHnV0gO6H0A+pS5tK EQUJ27eXYCnpl5LtYCje17EXcLsfgX/7kgp9r2TNgKI9P8uzZvEeBY/QtmVopxHLUl Sa/0dEXeZ8oGhrgIOc96kLhUXsn91V5CvvgS73+uQSAsU5iYi4rxlvIIis2Yp4cROy uVRB1hDaFdPXskqp/2EhnVaFKaCwcLYunoztx94fsr8fb0VWNPI2SOUkN6NoGCqAXN alf3XZH3XK4vQ== Sender: linux-usb-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org When a uas disk is plugged into an external hub, uas_probe() will be called by the hub thread to do the probe. It will first create a SCSI host and then do the scan for this host. During the scan, it will probe the LUN using SCSI INQUERY command which will be packed in the URB and submitted to uas disk. There might be a chance that this external hub with uas disk attached is unplugged during the scan. In this case, uas driver will fail to submit the URB (due to the NOTATTACHED state of uas device) and try to put this SCSI command back to request queue waiting for next chance to run. In normal case, this cycle will terminate when hub thread gets disconnection event and calls into uas_disconnect() accordingly. But in this case, uas_disconnect() will not be called because hub thread of external hub gets stuck waiting for the completion of this SCSI command. A deadlock happened. In this fix, uas will call scsi_scan_host() asynchronously to avoid the blocking of hub thread. Signed-off-by: EJ Hsu Acked-by: Oliver Neukum --- drivers/usb/storage/uas.c | 23 ++++++++++++++++++++++- 1 file changed, 22 insertions(+), 1 deletion(-) diff --git a/drivers/usb/storage/uas.c b/drivers/usb/storage/uas.c index 95bba3ba6ac6..3670fda02c34 100644 --- a/drivers/usb/storage/uas.c +++ b/drivers/usb/storage/uas.c @@ -45,6 +45,7 @@ struct uas_dev_info { struct scsi_cmnd *cmnd[MAX_CMNDS]; spinlock_t lock; struct work_struct work; + struct work_struct scan_work; /* for async scanning */ }; enum { @@ -114,6 +115,17 @@ static void uas_do_work(struct work_struct *work) spin_unlock_irqrestore(&devinfo->lock, flags); } +static void uas_scan_work(struct work_struct *work) +{ + struct uas_dev_info *devinfo = + container_of(work, struct uas_dev_info, scan_work); + struct Scsi_Host *shost = usb_get_intfdata(devinfo->intf); + + dev_dbg(&devinfo->intf->dev, "starting scan\n"); + scsi_scan_host(shost); + dev_dbg(&devinfo->intf->dev, "scan complete\n"); +} + static void uas_add_work(struct uas_cmd_info *cmdinfo) { struct scsi_pointer *scp = (void *)cmdinfo; @@ -982,6 +994,7 @@ static int uas_probe(struct usb_interface *intf, const struct usb_device_id *id) init_usb_anchor(&devinfo->data_urbs); spin_lock_init(&devinfo->lock); INIT_WORK(&devinfo->work, uas_do_work); + INIT_WORK(&devinfo->scan_work, uas_scan_work); result = uas_configure_endpoints(devinfo); if (result) @@ -998,7 +1011,9 @@ static int uas_probe(struct usb_interface *intf, const struct usb_device_id *id) if (result) goto free_streams; - scsi_scan_host(shost); + /* Submit the delayed_work for SCSI-device scanning */ + schedule_work(&devinfo->scan_work); + return result; free_streams: @@ -1166,6 +1181,12 @@ static void uas_disconnect(struct usb_interface *intf) usb_kill_anchored_urbs(&devinfo->data_urbs); uas_zap_pending(devinfo, DID_NO_CONNECT); + /* + * Prevent SCSI scanning (if it hasn't started yet) + * or wait for the SCSI-scanning routine to stop. + */ + cancel_work_sync(&devinfo->scan_work); + scsi_remove_host(shost); uas_free_streams(devinfo); scsi_host_put(shost);