From patchwork Mon Jul 9 06:10:37 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Nicholas A. Bellinger" X-Patchwork-Id: 1170991 Return-Path: X-Original-To: patchwork-kvm@patchwork.kernel.org Delivered-To: patchwork-process-083081@patchwork1.kernel.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by patchwork1.kernel.org (Postfix) with ESMTP id E058F3FD4F for ; Mon, 9 Jul 2012 06:15:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751623Ab2GIGNZ (ORCPT ); Mon, 9 Jul 2012 02:13:25 -0400 Received: from mail.linux-iscsi.org ([67.23.28.174]:44458 "EHLO linux-iscsi.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751043Ab2GIGNX (ORCPT ); Mon, 9 Jul 2012 02:13:23 -0400 Received: from linux-iscsi.org (localhost [127.0.0.1]) by linux-iscsi.org (Postfix) with ESMTP id 3365622D9D0; Mon, 9 Jul 2012 06:10:51 +0000 (UTC) From: "Nicholas A. Bellinger" To: target-devel Cc: linux-scsi , lf-virt , kvm-devel , Stefan Hajnoczi , Zhi Yong Wu , Anthony Liguori , Paolo Bonzini , "Michael S. Tsirkin" , Christoph Hellwig , Jens Axboe , Hannes Reinecke , Nicholas Bellinger Subject: [PATCH] tcm_vhost: Convert to cmwq submission for I/O dispatch Date: Mon, 9 Jul 2012 06:10:37 +0000 Message-Id: <1341814237-24247-1-git-send-email-nab@linux-iscsi.org> X-Mailer: git-send-email 1.7.2.5 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org From: Nicholas Bellinger This patch converts tcm_vhost to use modern concurrency managed workqueues to offload setup of tcm_vhost_cmd descriptors to a kworker CPU thread that is running on the same core as the vhost thread pulling elements off the virtqueue from within vhost_scsi_handle_vq(). This includes the addition of tcm_vhost_submission_work() to perform the LUN lookup, target_setup_cmd_from_cdb(), transport_generic_map_mem_to_cmd() and transport_handle_cdb_direct() calls for setup -> memory map -> backend I/O execution. Also, now remove the legacy tcm_vhost_new_cmd_map() code originally used to perform memory map -> backend I/O execution from transport_processing_thread() process context. Cc: Christoph Hellwig Cc: Stefan Hajnoczi Cc: Zhi Yong Wu Cc: Michael S. Tsirkin Cc: Paolo Bonzini Cc: Hannes Reinecke Signed-off-by: Nicholas Bellinger --- drivers/vhost/tcm_vhost.c | 168 ++++++++++++++++++++++++--------------------- drivers/vhost/tcm_vhost.h | 6 ++- 2 files changed, 96 insertions(+), 78 deletions(-) diff --git a/drivers/vhost/tcm_vhost.c b/drivers/vhost/tcm_vhost.c index 81b77f3..da0b8ac 100644 --- a/drivers/vhost/tcm_vhost.c +++ b/drivers/vhost/tcm_vhost.c @@ -67,6 +67,8 @@ struct vhost_scsi { /* Local pointer to allocated TCM configfs fabric module */ static struct target_fabric_configfs *tcm_vhost_fabric_configfs; +static struct workqueue_struct *tcm_vhost_workqueue; + /* Global spinlock to protect tcm_vhost TPG list for vhost IOCTL access */ static DEFINE_MUTEX(tcm_vhost_mutex); static LIST_HEAD(tcm_vhost_list); @@ -247,55 +249,6 @@ static u32 tcm_vhost_tpg_get_inst_index(struct se_portal_group *se_tpg) return 1; } -/* - * Called by struct target_core_fabric_ops->new_cmd_map() - * - * Always called in process context. A non zero return value - * here will signal to handle an exception based on the return code. - */ -static int tcm_vhost_new_cmd_map(struct se_cmd *se_cmd) -{ - struct tcm_vhost_cmd *tv_cmd = container_of(se_cmd, - struct tcm_vhost_cmd, tvc_se_cmd); - struct scatterlist *sg_ptr, *sg_bidi_ptr = NULL; - u32 sg_no_bidi = 0; - int ret; - /* - * Allocate the necessary tasks to complete the received CDB+data - */ - ret = target_setup_cmd_from_cdb(se_cmd, tv_cmd->tvc_cdb); - if (ret != 0) - return ret; - /* - * Setup the struct scatterlist memory from the received - * struct tcm_vhost_cmd.. - */ - if (tv_cmd->tvc_sgl_count) { - sg_ptr = tv_cmd->tvc_sgl; - /* - * For BIDI commands, pass in the extra READ buffer - * to transport_generic_map_mem_to_cmd() below.. - */ -/* FIXME: Fix BIDI operation in tcm_vhost_new_cmd_map() */ -#if 0 - if (se_cmd->se_cmd_flags & SCF_BIDI) { - mem_bidi_ptr = NULL; - sg_no_bidi = 0; - } -#endif - } else { - /* - * Used for DMA_NONE - */ - sg_ptr = NULL; - } - - /* Tell the core about our preallocated memory */ - return transport_generic_map_mem_to_cmd(se_cmd, sg_ptr, - tv_cmd->tvc_sgl_count, sg_bidi_ptr, - sg_no_bidi); -} - static void tcm_vhost_release_cmd(struct se_cmd *se_cmd) { return; @@ -509,12 +462,6 @@ static struct tcm_vhost_cmd *vhost_scsi_allocate_cmd( if (bidi) se_cmd->se_cmd_flags |= SCF_BIDI; #endif - /* - * From here the rest of the se_cmd will be setup and dispatched - * via tcm_vhost_new_cmd_map() from TCM backend thread context - * after transport_generic_handle_cdb_map() has been called from - * vhost_scsi_handle_vq() below.. - */ return tv_cmd; } @@ -611,6 +558,71 @@ static int vhost_scsi_map_iov_to_sgl(struct tcm_vhost_cmd *tv_cmd, return 0; } +static void tcm_vhost_submission_work(struct work_struct *work) +{ + struct tcm_vhost_cmd *tv_cmd = + container_of(work, struct tcm_vhost_cmd, work); + struct se_cmd *se_cmd = &tv_cmd->tvc_se_cmd; + struct scatterlist *sg_ptr, *sg_bidi_ptr = NULL; + int rc, sg_no_bidi = 0; + /* + * Locate the struct se_lun pointer based on v_req->lun, and + * attach it to struct se_cmd + */ + rc = transport_lookup_cmd_lun(&tv_cmd->tvc_se_cmd, tv_cmd->tvc_lun); + if (rc < 0) { + pr_err("Failed to look up lun: %d\n", tv_cmd->tvc_lun); + transport_send_check_condition_and_sense(&tv_cmd->tvc_se_cmd, + tv_cmd->tvc_se_cmd.scsi_sense_reason, 0); + transport_generic_free_cmd(se_cmd, 0); + return; + } + + rc = target_setup_cmd_from_cdb(se_cmd, tv_cmd->tvc_cdb); + if (rc == -ENOMEM) { + transport_send_check_condition_and_sense(se_cmd, + TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE, 0); + transport_generic_free_cmd(se_cmd, 0); + return; + } else if (rc < 0) { + if (se_cmd->se_cmd_flags & SCF_SCSI_RESERVATION_CONFLICT) + tcm_vhost_queue_status(se_cmd); + else + transport_send_check_condition_and_sense(se_cmd, + se_cmd->scsi_sense_reason, 0); + transport_generic_free_cmd(se_cmd, 0); + return; + } + + if (tv_cmd->tvc_sgl_count) { + sg_ptr = tv_cmd->tvc_sgl; + /* + * For BIDI commands, pass in the extra READ buffer + * to transport_generic_map_mem_to_cmd() below.. + */ +/* FIXME: Fix BIDI operation in tcm_vhost_submission_work() */ +#if 0 + if (se_cmd->se_cmd_flags & SCF_BIDI) { + sg_bidi_ptr = NULL; + sg_no_bidi = 0; + } +#endif + } else { + sg_ptr = NULL; + } + + rc = transport_generic_map_mem_to_cmd(se_cmd, sg_ptr, + tv_cmd->tvc_sgl_count, sg_bidi_ptr, + sg_no_bidi); + if (rc < 0) { + transport_send_check_condition_and_sense(se_cmd, + se_cmd->scsi_sense_reason, 0); + transport_generic_free_cmd(se_cmd, 0); + return; + } + transport_handle_cdb_direct(se_cmd); +} + static void vhost_scsi_handle_vq(struct vhost_scsi *vs) { struct vhost_virtqueue *vq = &vs->vqs[2]; @@ -619,7 +631,7 @@ static void vhost_scsi_handle_vq(struct vhost_scsi *vs) struct tcm_vhost_cmd *tv_cmd; u32 exp_data_len, data_first, data_num, data_direction; unsigned out, in, i; - int head, ret, lun; + int head, ret; /* Must use ioctl VHOST_SCSI_SET_ENDPOINT */ tv_tpg = vs->vs_tpg; @@ -732,10 +744,10 @@ static void vhost_scsi_handle_vq(struct vhost_scsi *vs) scsi_command_size(tv_cmd->tvc_cdb), TCM_VHOST_MAX_CDB_SIZE); break; /* TODO */ } - lun = ((v_req.lun[2] << 8) | v_req.lun[3]) & 0x3FFF; + tv_cmd->tvc_lun = ((v_req.lun[2] << 8) | v_req.lun[3]) & 0x3FFF; pr_debug("vhost_scsi got command opcode: %#02x, lun: %d\n", - tv_cmd->tvc_cdb[0], lun); + tv_cmd->tvc_cdb[0], tv_cmd->tvc_lun); if (data_direction != DMA_NONE) { ret = vhost_scsi_map_iov_to_sgl(tv_cmd, &vq->iov[data_first], @@ -753,22 +765,13 @@ static void vhost_scsi_handle_vq(struct vhost_scsi *vs) */ tv_cmd->tvc_vq_desc = head; /* - * Locate the struct se_lun pointer based on v_req->lun, and - * attach it to struct se_cmd - */ - if (transport_lookup_cmd_lun(&tv_cmd->tvc_se_cmd, lun) < 0) { - pr_err("Failed to look up lun: %d\n", lun); - /* NON_EXISTENT_LUN */ - transport_send_check_condition_and_sense(&tv_cmd->tvc_se_cmd, - tv_cmd->tvc_se_cmd.scsi_sense_reason, 0); - continue; - } - /* - * Now queue up the newly allocated se_cmd to be processed - * within TCM thread context to finish the setup and dispatched - * into a TCM backend struct se_device. + * Dispatch tv_cmd descriptor for cmwq execution in process + * context provided by tcm_vhost_workqueue. This also ensures + * tv_cmd is executed on the same kworker CPU as this vhost + * thread to gain positive L2 cache locality effects.. */ - transport_generic_handle_cdb_map(&tv_cmd->tvc_se_cmd); + INIT_WORK(&tv_cmd->work, tcm_vhost_submission_work); + queue_work(tcm_vhost_workqueue, &tv_cmd->work); } mutex_unlock(&vq->mutex); @@ -1478,7 +1481,6 @@ static struct target_core_fabric_ops tcm_vhost_ops = { .tpg_alloc_fabric_acl = tcm_vhost_alloc_fabric_acl, .tpg_release_fabric_acl = tcm_vhost_release_fabric_acl, .tpg_get_inst_index = tcm_vhost_tpg_get_inst_index, - .new_cmd_map = tcm_vhost_new_cmd_map, .release_cmd = tcm_vhost_release_cmd, .shutdown_session = tcm_vhost_shutdown_session, .close_session = tcm_vhost_close_session, @@ -1570,23 +1572,35 @@ static void tcm_vhost_deregister_configfs(void) static int __init tcm_vhost_init(void) { - int ret; + int ret = -ENOMEM; + + tcm_vhost_workqueue = alloc_workqueue("tcm_vhost", 0, 0); + if (!tcm_vhost_workqueue) + goto out; ret = vhost_scsi_register(); if (ret < 0) - return ret; + goto out_destroy_workqueue; ret = tcm_vhost_register_configfs(); if (ret < 0) - return ret; + goto out_vhost_scsi_deregister; return 0; + +out_vhost_scsi_deregister: + vhost_scsi_deregister(); +out_destroy_workqueue: + destroy_workqueue(tcm_vhost_workqueue); +out: + return ret; }; static void tcm_vhost_exit(void) { tcm_vhost_deregister_configfs(); vhost_scsi_deregister(); + destroy_workqueue(tcm_vhost_workqueue); }; MODULE_DESCRIPTION("TCM_VHOST series fabric driver"); diff --git a/drivers/vhost/tcm_vhost.h b/drivers/vhost/tcm_vhost.h index 0e8951b..9d6cace 100644 --- a/drivers/vhost/tcm_vhost.h +++ b/drivers/vhost/tcm_vhost.h @@ -9,14 +9,18 @@ struct tcm_vhost_cmd { u64 tvc_tag; /* The number of scatterlists associated with this cmd */ u32 tvc_sgl_count; + /* Saved unpacked SCSI LUN for tcm_vhost_submission_work() */ + u32 tvc_lun; /* Pointer to the SGL formatted memory from virtio-scsi */ struct scatterlist *tvc_sgl; /* Pointer to response */ struct virtio_scsi_cmd_resp __user *tvc_resp; /* Pointer to vhost_scsi for our device */ struct vhost_scsi *tvc_vhost; - /* The TCM I/O descriptor that is accessed via container_of() */ + /* The TCM I/O descriptor that is accessed via container_of() */ struct se_cmd tvc_se_cmd; + /* work item used for cmwq dispatch to tcm_vhost_submission_work() */ + struct work_struct work; /* Copy of the incoming SCSI command descriptor block (CDB) */ unsigned char tvc_cdb[TCM_VHOST_MAX_CDB_SIZE]; /* Sense buffer that will be mapped into outgoing status */