Completed commands are queued and processed from the vhost worker
thread. A lock must be used for mutual exclusion.
Signed-off-by: Stefan Hajnoczi <stefanha@xxxxxxxxxxxxxxxxxx>
---
drivers/target/tcm_vhost/tcm_vhost_scsi.c | 34 +++++++++++++++++++++-------
drivers/target/tcm_vhost/tcm_vhost_scsi.h | 1 +
2 files changed, 26 insertions(+), 9 deletions(-)
diff --git a/drivers/target/tcm_vhost/tcm_vhost_scsi.c b/drivers/target/tcm_vhost/tcm_vhost_scsi.c
index f0900f1..93b3a82 100644
--- a/drivers/target/tcm_vhost/tcm_vhost_scsi.c
+++ b/drivers/target/tcm_vhost/tcm_vhost_scsi.c
@@ -54,6 +54,26 @@ 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
@@ -64,11 +84,8 @@ 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 tcm_vhost_cmd *tv_cmd;
- struct tcm_vhost_cmd *tmp;
- /* TODO locking? */
- list_for_each_entry_safe(tv_cmd, tmp, &vs->vs_completion_list,
- tvc_completion_list) {
+ while ((tv_cmd = vhost_scsi_get_cmd_from_completion(vs)) != NULL) {
struct virtio_scsi_footer v_footer;
struct se_cmd *se_cmd = &tv_cmd->tvc_se_cmd;
int ret;
@@ -76,8 +93,6 @@ static void vhost_scsi_complete_cmd_work(struct vhost_work *work)
printk("%s tv_cmd %p resid %u status %#02x\n", __func__,
tv_cmd, se_cmd->residual_count, se_cmd->scsi_status);
- list_del(&tv_cmd->tvc_completion_list);
-
memset(&v_footer, 0, sizeof(v_footer));
v_footer.resid = se_cmd->residual_count;
/* TODO is status_qualifier field needed? */
@@ -104,11 +119,11 @@ void vhost_scsi_complete_cmd(struct tcm_vhost_cmd *tv_cmd)
printk("%s tv_cmd %p\n", __func__, tv_cmd);
- /* TODO lock tvc_completion_list? */
+ spin_lock_bh(&vs->vs_completion_lock);
list_add_tail(&tv_cmd->tvc_completion_list, &vs->vs_completion_list);
- vhost_work_queue(&vs->dev, &vs->vs_completion_work);
+ spin_unlock_bh(&vs->vs_completion_lock);
- /* TODO is tv_cmd freed by called after this? Need to keep hold of reference until vhost worker thread is done */
+ vhost_work_queue(&vs->dev, &vs->vs_completion_work);
}
static struct tcm_vhost_cmd *vhost_scsi_allocate_cmd(
@@ -533,6 +548,7 @@ static int vhost_scsi_open(struct inode *inode, struct file *f)
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->cmd_vq.handle_kick = vhost_scsi_handle_kick;
r = vhost_dev_init(&s->dev, &s->cmd_vq, 1);
diff --git a/drivers/target/tcm_vhost/tcm_vhost_scsi.h b/drivers/target/tcm_vhost/tcm_vhost_scsi.h
index d6a8aae..441a424 100644
--- a/drivers/target/tcm_vhost/tcm_vhost_scsi.h
+++ b/drivers/target/tcm_vhost/tcm_vhost_scsi.h
@@ -6,6 +6,7 @@ struct vhost_scsi {
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 vs_completion_list */
};
extern int __init vhost_scsi_register(void);
--
1.7.9.1
--
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