From 9d6064a347a8e15451cbdf6286542d402c9da24c Mon Sep 17 00:00:00 2001 From: Asias He Date: Sun, 6 Jan 2013 14:36:13 +0800 Subject: [PATCH] tcm_vhost: Use llist for cmd completion list This drops the cmd completion list spin lock and makes the cmd completion queue lock-less. Signed-off-by: Asias He Signed-off-by: Nicholas Bellinger --- drivers/vhost/tcm_vhost.c | 46 +++++++++++++--------------------------------- drivers/vhost/tcm_vhost.h | 2 +- 2 files changed, 14 insertions(+), 34 deletions(-) diff --git a/drivers/vhost/tcm_vhost.c b/drivers/vhost/tcm_vhost.c index 22321cf..77d760b 100644 --- a/drivers/vhost/tcm_vhost.c +++ b/drivers/vhost/tcm_vhost.c @@ -47,6 +47,7 @@ #include #include /* TODO vhost.h currently depends on this */ #include +#include #include "vhost.c" #include "vhost.h" @@ -64,8 +65,7 @@ struct vhost_scsi { struct vhost_virtqueue vqs[3]; struct vhost_work vs_completion_work; /* cmd completion work item */ - struct list_head vs_completion_list; /* cmd completion queue */ - spinlock_t vs_completion_lock; /* protects s_completion_list */ + struct llist_head vs_completion_list; /* cmd completion queue */ }; /* Local pointer to allocated TCM configfs fabric module */ @@ -301,9 +301,7 @@ static void vhost_scsi_complete_cmd(struct tcm_vhost_cmd *tv_cmd) { struct vhost_scsi *vs = tv_cmd->tvc_vhost; - spin_lock_bh(&vs->vs_completion_lock); - list_add_tail(&tv_cmd->tvc_completion_list, &vs->vs_completion_list); - spin_unlock_bh(&vs->vs_completion_lock); + llist_add(&tv_cmd->tvc_completion_list, &vs->vs_completion_list); vhost_work_queue(&vs->dev, &vs->vs_completion_work); } @@ -347,27 +345,6 @@ static void vhost_scsi_free_cmd(struct tcm_vhost_cmd *tv_cmd) kfree(tv_cmd); } -/* Dequeue a command from the completion list */ -static struct tcm_vhost_cmd *vhost_scsi_get_cmd_from_completion( - struct vhost_scsi *vs) -{ - struct tcm_vhost_cmd *tv_cmd = NULL; - - spin_lock_bh(&vs->vs_completion_lock); - if (list_empty(&vs->vs_completion_list)) { - spin_unlock_bh(&vs->vs_completion_lock); - return NULL; - } - - list_for_each_entry(tv_cmd, &vs->vs_completion_list, - tvc_completion_list) { - list_del(&tv_cmd->tvc_completion_list); - break; - } - spin_unlock_bh(&vs->vs_completion_lock); - return tv_cmd; -} - /* Fill in status and signal that we are done processing this command * * This is scheduled in the vhost work queue so we are called with the owner @@ -377,12 +354,18 @@ static void vhost_scsi_complete_cmd_work(struct vhost_work *work) { struct vhost_scsi *vs = container_of(work, struct vhost_scsi, vs_completion_work); + struct virtio_scsi_cmd_resp v_rsp; struct tcm_vhost_cmd *tv_cmd; + struct llist_node *llnode; + struct se_cmd *se_cmd; + int ret; - while ((tv_cmd = vhost_scsi_get_cmd_from_completion(vs))) { - struct virtio_scsi_cmd_resp v_rsp; - struct se_cmd *se_cmd = &tv_cmd->tvc_se_cmd; - int ret; + llnode = llist_del_all(&vs->vs_completion_list); + while (llnode) { + tv_cmd = llist_entry(llnode, struct tcm_vhost_cmd, + tvc_completion_list); + llnode = llist_next(llnode); + se_cmd = &tv_cmd->tvc_se_cmd; pr_debug("%s tv_cmd %p resid %u status %#02x\n", __func__, tv_cmd, se_cmd->residual_count, se_cmd->scsi_status); @@ -426,7 +409,6 @@ static struct tcm_vhost_cmd *vhost_scsi_allocate_cmd( pr_err("Unable to allocate struct tcm_vhost_cmd\n"); return ERR_PTR(-ENOMEM); } - INIT_LIST_HEAD(&tv_cmd->tvc_completion_list); tv_cmd->tvc_tag = v_req->tag; tv_cmd->tvc_task_attr = v_req->task_attr; tv_cmd->tvc_exp_data_len = exp_data_len; @@ -857,8 +839,6 @@ static int vhost_scsi_open(struct inode *inode, struct file *f) return -ENOMEM; vhost_work_init(&s->vs_completion_work, vhost_scsi_complete_cmd_work); - INIT_LIST_HEAD(&s->vs_completion_list); - spin_lock_init(&s->vs_completion_lock); s->vqs[VHOST_SCSI_VQ_CTL].handle_kick = vhost_scsi_ctl_handle_kick; s->vqs[VHOST_SCSI_VQ_EVT].handle_kick = vhost_scsi_evt_handle_kick; diff --git a/drivers/vhost/tcm_vhost.h b/drivers/vhost/tcm_vhost.h index 7e87c63..47ee80b 100644 --- a/drivers/vhost/tcm_vhost.h +++ b/drivers/vhost/tcm_vhost.h @@ -34,7 +34,7 @@ struct tcm_vhost_cmd { /* Sense buffer that will be mapped into outgoing status */ unsigned char tvc_sense_buf[TRANSPORT_SENSE_BUFFER]; /* Completed commands list, serviced from vhost worker thread */ - struct list_head tvc_completion_list; + struct llist_node tvc_completion_list; }; struct tcm_vhost_nexus { -- 2.7.4