On 16.08.2022 09:43, Andrey Zhadchenko wrote:
We want to support several vhost workers. The first step is to
rework vhost to use array of workers rather than single pointer.
Update creation and cleanup routines.
https://jira.sw.ru/browse/PSBM-139414
Signed-off-by: Andrey Zhadchenko <andrey.zhadche...@virtuozzo.com>
---
drivers/vhost/vhost.c | 75 +++++++++++++++++++++++++++++++------------
drivers/vhost/vhost.h | 10 +++++-
2 files changed, 63 insertions(+), 22 deletions(-)
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index a0bfc77c6a43..968601325a37 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -231,11 +231,24 @@ void vhost_poll_stop(struct vhost_poll *poll)
}
EXPORT_SYMBOL_GPL(vhost_poll_stop);
+static void vhost_work_queue_at_worker(struct vhost_worker *w,
+ struct vhost_work *work)
+{
+ 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, &w->work_list);
+ wake_up_process(w->worker);
+ }
+}
+
void vhost_work_dev_flush(struct vhost_dev *dev)
{
struct vhost_flush_struct flush;
- if (dev->worker) {
+ if (dev->workers[0].worker) {
init_completion(&flush.wait_event);
vhost_work_init(&flush.work, vhost_flush_work);
@@ -255,17 +268,12 @@ EXPORT_SYMBOL_GPL(vhost_poll_flush);
void vhost_work_queue(struct vhost_dev *dev, struct vhost_work *work)
{
- if (!dev->worker)
+ struct vhost_worker *w = &dev->workers[0];
+
+ if (!w->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->work_list);
- wake_up_process(dev->worker);
- }
+ vhost_work_queue_at_worker(w, work);
}
EXPORT_SYMBOL_GPL(vhost_work_queue);
@@ -341,9 +349,29 @@ static void vhost_vq_reset(struct vhost_dev *dev,
__vhost_vq_meta_reset(vq);
}
+static void vhost_worker_reset(struct vhost_worker *w)
+{
+ init_llist_head(&w->work_list);
+ w->worker = NULL;
+}
+
+void vhost_cleanup_workers(struct vhost_dev *dev)
+{
+ int i;
+
+ for (i = 0; i < dev->nworkers; ++i) {
+ WARN_ON(!llist_empty(&dev->workers[i].work_list));
+ kthread_stop(dev->workers[i].worker);
+ vhost_worker_reset(&dev->workers[i]);
+ }
+
+ dev->nworkers = 0;
+}
+
static int vhost_worker(void *data)
{
- struct vhost_dev *dev = data;
+ struct vhost_worker *w = data;
+ struct vhost_dev *dev = w->dev;
struct vhost_work *work, *work_next;
struct llist_node *node;
@@ -358,7 +386,7 @@ static int vhost_worker(void *data)
break;
}
- node = llist_del_all(&dev->work_list);
+ node = llist_del_all(&w->work_list);
if (!node)
schedule();
@@ -481,7 +509,6 @@ void vhost_dev_init(struct vhost_dev *dev,
dev->umem = NULL;
dev->iotlb = NULL;
dev->mm = NULL;
- dev->worker = NULL;
dev->iov_limit = iov_limit;
dev->weight = weight;
dev->byte_weight = byte_weight;
@@ -493,6 +520,11 @@ void vhost_dev_init(struct vhost_dev *dev,
INIT_LIST_HEAD(&dev->pending_list);
spin_lock_init(&dev->iotlb_lock);
+ dev->nworkers = 0;
+ for (i = 0; i < VHOST_MAX_WORKERS; ++i) {
+ dev->workers[i].dev = dev;
+ vhost_worker_reset(&dev->workers[i]);
+ }
for (i = 0; i < dev->nvqs; ++i) {
vq = dev->vqs[i];
@@ -602,7 +634,8 @@ long vhost_dev_set_owner(struct vhost_dev *dev)
goto err_worker;
}
- dev->worker = worker;
+ dev->workers[0].worker = worker;
+ dev->nworkers = 1;
wake_up_process(worker); /* avoid contributing to loadavg */
err = vhost_attach_cgroups(dev);
@@ -616,9 +649,10 @@ long vhost_dev_set_owner(struct vhost_dev *dev)
return 0;
err_cgroup:
- if (dev->worker) {
- kthread_stop(dev->worker);
- dev->worker = NULL;
+ dev->nworkers = 0;
+ if (dev->workers[0].worker) {
+ kthread_stop(dev->workers[0].worker);
+ dev->workers[0].worker = NULL;
This place is a bit out of sync here:
we do state here there can be only 1 worker,
but vhost_cleanup_workers() and vhost_dev_init() already have a loop on
dev->nworkers in this patch.
Technically there is no problem here, the code is correct, just non-glossy.
}
err_worker:
vhost_detach_mm(dev);
@@ -701,6 +735,7 @@ void vhost_dev_cleanup(struct vhost_dev *dev)
eventfd_ctx_put(dev->vqs[i]->call_ctx.ctx);
vhost_vq_reset(dev, dev->vqs[i]);
}
+
vhost_dev_free_iovecs(dev);
if (dev->log_ctx)
eventfd_ctx_put(dev->log_ctx);
@@ -712,10 +747,8 @@ void vhost_dev_cleanup(struct vhost_dev *dev)
dev->iotlb = NULL;
vhost_clear_msg(dev);
wake_up_interruptible_poll(&dev->wait, EPOLLIN | EPOLLRDNORM);
- WARN_ON(!llist_empty(&dev->work_list));
- if (dev->worker) {
- kthread_stop(dev->worker);
- dev->worker = NULL;
+ if (dev->use_worker) {
+ vhost_cleanup_workers(dev);
dev->kcov_handle = 0;
}
vhost_detach_mm(dev);
diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
index 638bb640d6b4..634ea828cbba 100644
--- a/drivers/vhost/vhost.h
+++ b/drivers/vhost/vhost.h
@@ -25,6 +25,13 @@ struct vhost_work {
unsigned long flags;
};
+#define VHOST_MAX_WORKERS 4
+struct vhost_worker {
+ struct task_struct *worker;
+ struct llist_head work_list;
+ struct vhost_dev *dev;
+};
+
/* Poll a file (eventfd or socket) */
/* Note: there's nothing vhost specific about this structure. */
struct vhost_poll {
@@ -149,7 +156,8 @@ struct vhost_dev {
int nvqs;
struct eventfd_ctx *log_ctx;
struct llist_head work_list;
- struct task_struct *worker;
+ struct vhost_worker workers[VHOST_MAX_WORKERS];
+ int nworkers;
struct vhost_iotlb *umem;
struct vhost_iotlb *iotlb;
spinlock_t iotlb_lock;
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