The final patches will allow us to have multiple vhost_workers per device
and be able to share them across devices. To prepare for that, this patch
allow us our internal work queueing, flush and cgroup attach functions to
take a vhost_worker as an arg.
The poll code required a change to the drivers, so the next patch will
convert that code.
Signed-off-by: Mike Christie <michael.christie@xxxxxxxxxx>
---
drivers/vhost/vhost.c | 136 ++++++++++++++++++++++++++++--------------
drivers/vhost/vhost.h | 4 +-
2 files changed, 94 insertions(+), 46 deletions(-)
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index a291cde95c43..4bfa9a7a51bb 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -231,20 +231,6 @@ void vhost_poll_stop(struct vhost_poll *poll)
}
EXPORT_SYMBOL_GPL(vhost_poll_stop);
-void vhost_work_dev_flush(struct vhost_dev *dev)
-{
- struct vhost_flush_struct flush;
-
- if (dev->worker) {
- init_completion(&flush.wait_event);
- vhost_work_init(&flush.work, vhost_flush_work);
-
- vhost_work_queue(dev, &flush.work);
- wait_for_completion(&flush.wait_event);
- }
-}
-EXPORT_SYMBOL_GPL(vhost_work_dev_flush);
-
/* Flush any work that has been scheduled. When calling this, don't hold any
* locks that are also used by the callback. */
void vhost_poll_flush(struct vhost_poll *poll)
@@ -253,26 +239,62 @@ void vhost_poll_flush(struct vhost_poll *poll)
}
EXPORT_SYMBOL_GPL(vhost_poll_flush);
-void vhost_work_queue(struct vhost_dev *dev, struct vhost_work *work)
+static void vhost_work_queue_on(struct vhost_work *work,
+ struct vhost_worker *worker)
{
- if (!dev->worker)
- return;
-
if (!test_and_set_bit(VHOST_WORK_QUEUED, &work->flags)) {
/* We can only add the work to the list after we're
* sure it was not in the list.
* test_and_set_bit() implies a memory barrier.
*/
- llist_add(&work->node, &dev->worker->work_list);
- wake_up_process(dev->worker->task);
+ llist_add(&work->node, &worker->work_list);
+ wake_up_process(worker->task);
}
}
+
+void vhost_work_queue(struct vhost_dev *dev, struct vhost_work *work)
+{
+ if (!dev->workers)
+ return;
+ /*
+ * devs with use_worker=true created by tools that do not support the
+ * worker creation ioctl will always have at least one worker.
+ */
+ vhost_work_queue_on(work, dev->workers[0]);
+}
EXPORT_SYMBOL_GPL(vhost_work_queue);
+static void vhost_work_dev_flush_on(struct vhost_worker *worker)
+{
+ struct vhost_flush_struct flush;
+
+ init_completion(&flush.wait_event);
+ vhost_work_init(&flush.work, vhost_flush_work);
+
+ vhost_work_queue_on(&flush.work, worker);
+ wait_for_completion(&flush.wait_event);
+}
+
+void vhost_work_dev_flush(struct vhost_dev *dev)
+{
+ int i;
+
+ for (i = 0; i < dev->num_workers; i++)
+ vhost_work_dev_flush_on(dev->workers[i]);
+}
+EXPORT_SYMBOL_GPL(vhost_work_dev_flush);
+
/* A lockless hint for busy polling code to exit the loop */
bool vhost_has_work(struct vhost_dev *dev)
{
- return dev->worker && !llist_empty(&dev->worker->work_list);
+ int i;
+
+ for (i = 0; i < dev->num_workers; i++) {
+ if (!llist_empty(&dev->workers[i]->work_list))
+ return true;
+ }
+
+ return false;
}
EXPORT_SYMBOL_GPL(vhost_has_work);
@@ -482,7 +504,8 @@ void vhost_dev_init(struct vhost_dev *dev,
dev->umem = NULL;
dev->iotlb = NULL;
dev->mm = NULL;
- dev->worker = NULL;
+ dev->workers = NULL;
+ dev->num_workers = 0;
dev->iov_limit = iov_limit;
dev->weight = weight;
dev->byte_weight = byte_weight;
@@ -531,14 +554,14 @@ static void vhost_attach_cgroups_work(struct vhost_work *work)
s->ret = cgroup_attach_task_all(s->owner, current);
}
-static int vhost_attach_cgroups(struct vhost_dev *dev)
+static int vhost_attach_cgroups_on(struct vhost_worker *worker)
{
struct vhost_attach_cgroups_struct attach;
attach.owner = current;
vhost_work_init(&attach.work, vhost_attach_cgroups_work);
- vhost_work_queue(dev, &attach.work);
- vhost_work_dev_flush(dev);
+ vhost_work_queue_on(&attach.work, worker);
+ vhost_work_dev_flush_on(worker);
return attach.ret;
}
@@ -579,20 +602,29 @@ static void vhost_detach_mm(struct vhost_dev *dev)
dev->mm = NULL;
}
-static void vhost_worker_free(struct vhost_dev *dev)
+static void vhost_worker_free(struct vhost_worker *worker)
{
- struct vhost_worker *worker = dev->worker;
-
- if (!worker)
- return;
-
- dev->worker = NULL;
WARN_ON(!llist_empty(&worker->work_list));
kthread_stop(worker->task);
kfree(worker);
}
-static int vhost_worker_create(struct vhost_dev *dev)
+static void vhost_workers_free(struct vhost_dev *dev)
+{
+ int i;
+
+ if (!dev->workers)
+ return;
+
+ for (i = 0; i < dev->num_workers; i++)
+ vhost_worker_free(dev->workers[i]);
+
+ kfree(dev->workers);
+ dev->num_workers = 0;
+ dev->workers = NULL;
+}
+
+static struct vhost_worker *vhost_worker_create(struct vhost_dev *dev)
{
struct vhost_worker *worker;
struct task_struct *task;
@@ -600,42 +632,56 @@ static int vhost_worker_create(struct vhost_dev *dev)
worker = kzalloc(sizeof(*worker), GFP_KERNEL);
if (!worker)
- return -ENOMEM;
+ return NULL;
- dev->worker = worker;
+ worker->id = dev->num_workers;
worker->dev = dev;
init_llist_head(&worker->work_list);
task = kthread_create(vhost_worker, worker, "vhost-%d", current->pid);
- if (IS_ERR(task)) {
- ret = PTR_ERR(task);
+ if (IS_ERR(task))
goto free_worker;
- }
worker->task = task;
wake_up_process(task); /* avoid contributing to loadavg */
- ret = vhost_attach_cgroups(dev);
+ ret = vhost_attach_cgroups_on(worker);
if (ret)
goto stop_worker;
- return 0;
+ return worker;
stop_worker:
kthread_stop(worker->task);
free_worker:
kfree(worker);
- dev->worker = NULL;
- return ret;
+ return NULL;
}
/* Caller must have device mutex */
static int vhost_worker_try_create_def(struct vhost_dev *dev)
{
- if (!dev->use_worker || dev->worker)
+ struct vhost_worker *worker;
+
+ if (!dev->use_worker || dev->workers)
return 0;
- return vhost_worker_create(dev);
+ dev->workers = kcalloc(1, sizeof(struct vhost_worker *), GFP_KERNEL);
+ if (!dev->workers)
+ return -ENOMEM;
+
+ worker = vhost_worker_create(dev);
+ if (!worker)
+ goto free_workers;
+
+ dev->workers[worker->id] = worker;
+ dev->num_workers++;
+ return 0;
+
+free_workers:
+ kfree(dev->workers);
+ dev->workers = NULL;
+ return -ENOMEM;
}
/* Caller should have device mutex */
@@ -750,7 +796,7 @@ void vhost_dev_cleanup(struct vhost_dev *dev)
dev->iotlb = NULL;
vhost_clear_msg(dev);
wake_up_interruptible_poll(&dev->wait, EPOLLIN | EPOLLRDNORM);
- vhost_worker_free(dev);
+ vhost_workers_free(dev);
vhost_detach_mm(dev);
dev->kcov_handle = 0;
}
diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
index bfc4563e612f..fa1af4106755 100644
--- a/drivers/vhost/vhost.h
+++ b/drivers/vhost/vhost.h
@@ -29,6 +29,7 @@ struct vhost_worker {
struct task_struct *task;
struct llist_head work_list;
struct vhost_dev *dev;
+ int id;
};
/* Poll a file (eventfd or socket) */
@@ -155,7 +156,8 @@ struct vhost_dev {
struct vhost_virtqueue **vqs;
int nvqs;
struct eventfd_ctx *log_ctx;
- struct vhost_worker *worker;
+ struct vhost_worker **workers;
+ int num_workers;
struct vhost_iotlb *umem;
struct vhost_iotlb *iotlb;
spinlock_t iotlb_lock;
--
2.25.1
