[Devel] [PATCH RHEL9 COMMIT] Revert "drivers/vhost: use array to store workers"
Konstantin Khorenko
khorenko at virtuozzo.com
Wed Nov 16 17:03:17 MSK 2022
The commit is pushed to "branch-rh9-5.14.0-70.22.1.vz9.17.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh9-5.14.0-70.22.1.vz9.17.9
------>
commit 71a06fa299a0ee1272e4e4ecd94dd5535f7eaee6
Author: Konstantin Khorenko <khorenko at virtuozzo.com>
Date: Wed Nov 16 15:56:19 2022 +0300
Revert "drivers/vhost: use array to store workers"
This reverts commit 10a96129bac144bbbc433b9738cd144ae0265d9a.
Will apply v5 of the patchset.
https://jira.sw.ru/browse/PSBM-139414
Signed-off-by: Konstantin Khorenko <khorenko at virtuozzo.com>
---
drivers/vhost/vhost.c | 75 +++++++++++++++------------------------------------
drivers/vhost/vhost.h | 10 +------
2 files changed, 22 insertions(+), 63 deletions(-)
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 968601325a37..a0bfc77c6a43 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -231,24 +231,11 @@ 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->workers[0].worker) {
+ if (dev->worker) {
init_completion(&flush.wait_event);
vhost_work_init(&flush.work, vhost_flush_work);
@@ -268,12 +255,17 @@ EXPORT_SYMBOL_GPL(vhost_poll_flush);
void vhost_work_queue(struct vhost_dev *dev, struct vhost_work *work)
{
- struct vhost_worker *w = &dev->workers[0];
-
- if (!w->worker)
+ if (!dev->worker)
return;
- vhost_work_queue_at_worker(w, 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, &dev->work_list);
+ wake_up_process(dev->worker);
+ }
}
EXPORT_SYMBOL_GPL(vhost_work_queue);
@@ -349,29 +341,9 @@ 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_worker *w = data;
- struct vhost_dev *dev = w->dev;
+ struct vhost_dev *dev = data;
struct vhost_work *work, *work_next;
struct llist_node *node;
@@ -386,7 +358,7 @@ static int vhost_worker(void *data)
break;
}
- node = llist_del_all(&w->work_list);
+ node = llist_del_all(&dev->work_list);
if (!node)
schedule();
@@ -509,6 +481,7 @@ 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;
@@ -520,11 +493,6 @@ 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];
@@ -634,8 +602,7 @@ long vhost_dev_set_owner(struct vhost_dev *dev)
goto err_worker;
}
- dev->workers[0].worker = worker;
- dev->nworkers = 1;
+ dev->worker = worker;
wake_up_process(worker); /* avoid contributing to loadavg */
err = vhost_attach_cgroups(dev);
@@ -649,10 +616,9 @@ long vhost_dev_set_owner(struct vhost_dev *dev)
return 0;
err_cgroup:
- dev->nworkers = 0;
- if (dev->workers[0].worker) {
- kthread_stop(dev->workers[0].worker);
- dev->workers[0].worker = NULL;
+ if (dev->worker) {
+ kthread_stop(dev->worker);
+ dev->worker = NULL;
}
err_worker:
vhost_detach_mm(dev);
@@ -735,7 +701,6 @@ 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);
@@ -747,8 +712,10 @@ void vhost_dev_cleanup(struct vhost_dev *dev)
dev->iotlb = NULL;
vhost_clear_msg(dev);
wake_up_interruptible_poll(&dev->wait, EPOLLIN | EPOLLRDNORM);
- if (dev->use_worker) {
- vhost_cleanup_workers(dev);
+ WARN_ON(!llist_empty(&dev->work_list));
+ if (dev->worker) {
+ kthread_stop(dev->worker);
+ dev->worker = NULL;
dev->kcov_handle = 0;
}
vhost_detach_mm(dev);
diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
index 634ea828cbba..638bb640d6b4 100644
--- a/drivers/vhost/vhost.h
+++ b/drivers/vhost/vhost.h
@@ -25,13 +25,6 @@ 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 {
@@ -156,8 +149,7 @@ struct vhost_dev {
int nvqs;
struct eventfd_ctx *log_ctx;
struct llist_head work_list;
- struct vhost_worker workers[VHOST_MAX_WORKERS];
- int nworkers;
+ struct task_struct *worker;
struct vhost_iotlb *umem;
struct vhost_iotlb *iotlb;
spinlock_t iotlb_lock;
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