From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mike Christie Date: Thu, 22 Oct 2020 00:35:03 +0000 Subject: [PATCH 17/17] vhost scsi: drop submission workqueue Message-Id: <1603326903-27052-18-git-send-email-michael.christie@oracle.com> List-Id: References: <1603326903-27052-1-git-send-email-michael.christie@oracle.com> In-Reply-To: <1603326903-27052-1-git-send-email-michael.christie@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: martin.petersen@oracle.com, linux-scsi@vger.kernel.org, target-devel@vger.kernel.org, mst@redhat.com, jasowang@redhat.com, pbonzini@redhat.com, stefanha@redhat.com, virtualization@lists.linux-foundation.org We can't control a VM's vhost scsi IO right now because the vhost worker is added to the VM's blk cgroup, but the vhost worker thread actually just passes the cmd to a vhost-scsi driver workqueue which ends up submitting the cmd to the block layer. This patch has us submit from the vhost worker thread and removes the work queue. Signed-off-by: Mike Christie --- drivers/vhost/scsi.c | 30 +++--------------------------- 1 file changed, 3 insertions(+), 27 deletions(-) diff --git a/drivers/vhost/scsi.c b/drivers/vhost/scsi.c index 4e91a90..3178bf54 100644 --- a/drivers/vhost/scsi.c +++ b/drivers/vhost/scsi.c @@ -101,8 +101,6 @@ struct vhost_scsi_cmd { struct vhost_scsi_nexus *tvc_nexus; /* The TCM I/O descriptor that is accessed via container_of() */ struct se_cmd tvc_se_cmd; - /* work item used for cmwq dispatch to vhost_scsi_submission_work() */ - struct work_struct work; /* Copy of the incoming SCSI command descriptor block (CDB) */ unsigned char tvc_cdb[VHOST_SCSI_MAX_CDB_SIZE]; /* Sense buffer that will be mapped into outgoing status */ @@ -240,8 +238,6 @@ struct vhost_scsi_ctx { struct iov_iter out_iter; }; -static struct workqueue_struct *vhost_scsi_workqueue; - /* Global spinlock to protect vhost_scsi TPG list for vhost IOCTL access */ static DEFINE_MUTEX(vhost_scsi_mutex); static LIST_HEAD(vhost_scsi_list); @@ -776,10 +772,8 @@ static int vhost_scsi_to_tcm_attr(int attr) return TCM_SIMPLE_TAG; } -static void vhost_scsi_submission_work(struct work_struct *work) +static void vhost_scsi_target_submit(struct vhost_scsi_cmd *cmd) { - struct vhost_scsi_cmd *cmd - container_of(work, struct vhost_scsi_cmd, work); struct vhost_scsi_nexus *tv_nexus; struct se_cmd *se_cmd = &cmd->tvc_se_cmd; struct scatterlist *sg_ptr, *sg_prot_ptr = NULL; @@ -1126,14 +1120,7 @@ static u16 vhost_buf_to_lun(u8 *lun_buf) * vhost_scsi_queue_data_in() and vhost_scsi_queue_status() */ cmd->tvc_vq_desc = vc.head; - /* - * Dispatch cmd descriptor for cmwq execution in process - * context provided by vhost_scsi_workqueue. This also ensures - * cmd is executed on the same kworker CPU as this vhost - * thread to gain positive L2 cache locality effects. - */ - INIT_WORK(&cmd->work, vhost_scsi_submission_work); - queue_work(vhost_scsi_workqueue, &cmd->work); + vhost_scsi_target_submit(cmd); ret = 0; err: /* @@ -2511,17 +2498,9 @@ static int __init vhost_scsi_init(void) " on "UTS_RELEASE"\n", VHOST_SCSI_VERSION, utsname()->sysname, utsname()->machine); - /* - * Use our own dedicated workqueue for submitting I/O into - * target core to avoid contention within system_wq. - */ - vhost_scsi_workqueue = alloc_workqueue("vhost_scsi", 0, 0); - if (!vhost_scsi_workqueue) - goto out; - ret = vhost_scsi_register(); if (ret < 0) - goto out_destroy_workqueue; + goto out; ret = target_register_template(&vhost_scsi_ops); if (ret < 0) @@ -2531,8 +2510,6 @@ static int __init vhost_scsi_init(void) out_vhost_scsi_deregister: vhost_scsi_deregister(); -out_destroy_workqueue: - destroy_workqueue(vhost_scsi_workqueue); out: return ret; }; @@ -2541,7 +2518,6 @@ static void vhost_scsi_exit(void) { target_unregister_template(&vhost_scsi_ops); vhost_scsi_deregister(); - destroy_workqueue(vhost_scsi_workqueue); }; MODULE_DESCRIPTION("VHOST_SCSI series fabric driver"); -- 1.8.3.1