From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934227AbdJQRct (ORCPT ); Tue, 17 Oct 2017 13:32:49 -0400 Received: from mx1.redhat.com ([209.132.183.28]:53938 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753302AbdJQRcr (ORCPT ); Tue, 17 Oct 2017 13:32:47 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com AE26033A18C Authentication-Results: ext-mx10.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx10.extmail.prod.ext.phx2.redhat.com; spf=fail smtp.mailfrom=cavery@redhat.com From: Cathy Avery To: kys@microsoft.com, hch@infradead.org, haiyangz@microsoft.com, jejb@linux.vnet.ibm.com, martin.petersen@oracle.com, dan.carpenter@oracle.com Cc: devel@linuxdriverproject.org, linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org Subject: [PATCH] scsi: storvsc: Allow only one remove lun work item to be issued per lun Date: Tue, 17 Oct 2017 13:32:45 -0400 Message-Id: <1508261565-23846-1-git-send-email-cavery@redhat.com> X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.39]); Tue, 17 Oct 2017 17:32:47 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When running multipath on a VM if all available paths go down the driver can schedule large amounts of storvsc_remove_lun work items to the same lun. In response to the failing paths typically storvsc responds by taking host->scan_mutex and issuing a TUR per lun. If there has been heavy IO to the failed device all the failed IOs are returned from the host. A remove lun work item is issued per failed IO. If the outstanding TURs have not been completed in a timely manner the scan_mutex is never released or released too late. Consequently the many remove lun work items are not completed as scsi_remove_device also tries to take host->scan_mutex. This results in dragging the VM down and sometimes completely. This patch only allows one remove lun to be issued to a particular lun while it is an instantiated member of the scsi stack. Changes since v1: Use single threaded workqueue to serialize work in storvsc_handle_error [Christoph Hellwig] Signed-off-by: Cathy Avery --- drivers/scsi/storvsc_drv.c | 27 ++++++++++++++++++++++----- 1 file changed, 22 insertions(+), 5 deletions(-) diff --git a/drivers/scsi/storvsc_drv.c b/drivers/scsi/storvsc_drv.c index 5e7200f..6febcdb 100644 --- a/drivers/scsi/storvsc_drv.c +++ b/drivers/scsi/storvsc_drv.c @@ -486,6 +486,8 @@ struct hv_host_device { unsigned int port; unsigned char path; unsigned char target; + struct workqueue_struct *handle_error_wq; + char work_q_name[20]; }; struct storvsc_scan_work { @@ -922,6 +924,7 @@ static void storvsc_handle_error(struct vmscsi_request *vm_srb, { struct storvsc_scan_work *wrk; void (*process_err_fn)(struct work_struct *work); + struct hv_host_device *host_dev = shost_priv(host); bool do_work = false; switch (SRB_STATUS(vm_srb->srb_status)) { @@ -988,7 +991,7 @@ static void storvsc_handle_error(struct vmscsi_request *vm_srb, wrk->lun = vm_srb->lun; wrk->tgt_id = vm_srb->target_id; INIT_WORK(&wrk->work, process_err_fn); - schedule_work(&wrk->work); + queue_work(host_dev->handle_error_wq, &wrk->work); } @@ -1803,10 +1806,19 @@ static int storvsc_probe(struct hv_device *device, if (stor_device->num_sc != 0) host->nr_hw_queues = stor_device->num_sc + 1; + /* + * Set the error handler work queue. + */ + snprintf(host_dev->work_q_name, sizeof(host_dev->work_q_name), + "storvsc_error_wq_%d", host->host_no); + host_dev->handle_error_wq = + create_singlethread_workqueue(host_dev->work_q_name); + if (!host_dev->handle_error_wq) + goto err_out2; /* Register the HBA and start the scsi bus scan */ ret = scsi_add_host(host, &device->device); if (ret != 0) - goto err_out2; + goto err_out3; if (!dev_is_ide) { scsi_scan_host(host); @@ -1815,7 +1827,7 @@ static int storvsc_probe(struct hv_device *device, device->dev_instance.b[4]); ret = scsi_add_device(host, 0, target, 0); if (ret) - goto err_out3; + goto err_out4; } #if IS_ENABLED(CONFIG_SCSI_FC_ATTRS) if (host->transportt == fc_transport_template) { @@ -1827,14 +1839,17 @@ static int storvsc_probe(struct hv_device *device, fc_host_port_name(host) = stor_device->port_name; stor_device->rport = fc_remote_port_add(host, 0, &ids); if (!stor_device->rport) - goto err_out3; + goto err_out4; } #endif return 0; -err_out3: +err_out4: scsi_remove_host(host); +err_out3: + destroy_workqueue(host_dev->handle_error_wq); + err_out2: /* * Once we have connected with the host, we would need to @@ -1858,6 +1873,7 @@ static int storvsc_remove(struct hv_device *dev) { struct storvsc_device *stor_device = hv_get_drvdata(dev); struct Scsi_Host *host = stor_device->host; + struct hv_host_device *host_dev = shost_priv(host); #if IS_ENABLED(CONFIG_SCSI_FC_ATTRS) if (host->transportt == fc_transport_template) { @@ -1865,6 +1881,7 @@ static int storvsc_remove(struct hv_device *dev) fc_remove_host(host); } #endif + destroy_workqueue(host_dev->handle_error_wq); scsi_remove_host(host); storvsc_dev_remove(dev); scsi_host_put(host); -- 2.5.0