[PATCH V4 01/12] vhost: add vhost_worker pointer to vhost_virtqueue

[Mike Christie <michael.christie@xxxxxxxxxx>]

This patchset allows userspace to map vqs to different workers. This
patch adds a worker pointer to the vq so we can store that info.

Signed-off-by: Mike Christie <michael.christie@xxxxxxxxxx>
---
 drivers/vhost/vhost.c | 24 +++++++++++++-----------
 drivers/vhost/vhost.h |  1 +
 2 files changed, 14 insertions(+), 11 deletions(-)

diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 9aa04fcdf210..9b4e7d74dab4 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -496,6 +496,7 @@ void vhost_dev_init(struct vhost_dev *dev,
 		vq->log = NULL;
 		vq->indirect = NULL;
 		vq->heads = NULL;
+		vq->worker = NULL;
 		vq->dev = dev;
 		mutex_init(&vq->mutex);
 		vhost_vq_reset(dev, vq);
@@ -574,15 +575,14 @@ static void vhost_worker_free(struct vhost_dev *dev)
 	kfree(worker);
 }
 
-static int vhost_worker_create(struct vhost_dev *dev)
+static struct vhost_worker *vhost_worker_create(struct vhost_dev *dev)
 {
 	struct vhost_worker *worker;
 	struct task_struct *task;
-	int ret;
 
 	worker = kzalloc(sizeof(*worker), GFP_KERNEL_ACCOUNT);
 	if (!worker)
-		return -ENOMEM;
+		return NULL;
 
 	dev->worker = worker;
 	worker->kcov_handle = kcov_common_handle();
@@ -594,25 +594,24 @@ static int vhost_worker_create(struct vhost_dev *dev)
 	 */
 	task = kernel_worker(vhost_worker, worker, NUMA_NO_NODE, CLONE_FS,
 			     KERN_WORKER_NO_FILES | KERN_WORKER_SIG_IGN);
-	if (IS_ERR(task)) {
-		ret = PTR_ERR(task);
+	if (IS_ERR(task))
 		goto free_worker;
-	}
 
 	worker->task = task;
 	kernel_worker_start(task, "vhost-%d", current->pid);
-	return 0;
+	return worker;
 
 free_worker:
 	kfree(worker);
 	dev->worker = NULL;
-	return ret;
+	return NULL;
 }
 
 /* Caller should have device mutex */
 long vhost_dev_set_owner(struct vhost_dev *dev)
 {
-	int err;
+	struct vhost_worker *worker;
+	int err, i;
 
 	/* Is there an owner already? */
 	if (vhost_dev_has_owner(dev)) {
@@ -623,9 +622,12 @@ long vhost_dev_set_owner(struct vhost_dev *dev)
 	vhost_attach_mm(dev);
 
 	if (dev->use_worker) {
-		err = vhost_worker_create(dev);
-		if (err)
+		worker = vhost_worker_create(dev);
+		if (!worker)
 			goto err_worker;
+
+		for (i = 0; i < dev->nvqs; i++)
+			dev->vqs[i]->worker = worker;
 	}
 
 	err = vhost_dev_alloc_iovecs(dev);
diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
index 09748694cb66..7ee38b4a2807 100644
--- a/drivers/vhost/vhost.h
+++ b/drivers/vhost/vhost.h
@@ -80,6 +80,7 @@ struct vhost_vring_call {
 /* The virtqueue structure describes a queue attached to a device. */
 struct vhost_virtqueue {
 	struct vhost_dev *dev;
+	struct vhost_worker *worker;
 
 	/* The actual ring of buffers. */
 	struct mutex mutex;
-- 
2.25.1