Use the common workqueue machanism for processing vhost work
by creating a unbound workqueue/vhost device. The backend workers
could still share work and are not visible to vhost.
Signed-off-by: Bandan Das <bsd@xxxxxxxxxx>
---
drivers/vhost/vhost.c | 103 +++++++++++++++++++++++++++++++++++++++++++-------
drivers/vhost/vhost.h | 2 +
2 files changed, 92 insertions(+), 13 deletions(-)
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index ad2146a..162e25e 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -30,6 +30,10 @@
#include "vhost.h"
+static int cmwq_worker = 1;
+module_param(cmwq_worker, int, 0444);
+MODULE_PARM_DESC(cmwq_worker, "Use cmwq for worker threads - Experimental, 1 - Enable; 0 - Disable");
+
static ushort max_mem_regions = 64;
module_param(max_mem_regions, ushort, 0444);
MODULE_PARM_DESC(max_mem_regions,
@@ -238,7 +242,10 @@ void vhost_work_queue(struct vhost_dev *dev, struct vhost_work *work)
list_add_tail(&work->node, &dev->work_list);
work->queue_seq++;
spin_unlock_irqrestore(&dev->work_lock, flags);
- wake_up_process(dev->worker);
+ if (cmwq_worker)
+ queue_work(dev->qworker, &dev->qwork);
+ else
+ wake_up_process(dev->worker);
} else {
spin_unlock_irqrestore(&dev->work_lock, flags);
}
@@ -370,6 +377,52 @@ static void vhost_dev_free_iovecs(struct vhost_dev *dev)
vhost_vq_free_iovecs(dev->vqs[i]);
}
+static void vhost_wq_worker(struct work_struct *qwork)
+{
+ struct vhost_dev *dev =
+ container_of(qwork, struct vhost_dev, qwork);
+ struct vhost_work *work = NULL;
+ unsigned uninitialized_var(seq);
+ struct mm_struct *prev_mm = NULL;
+ mm_segment_t oldfs = get_fs();
+
+ set_fs(USER_DS);
+
+ for (;;) {
+ spin_lock_irq(&dev->work_lock);
+ if (list_empty(&dev->work_list)) {
+ spin_unlock(&dev->work_lock);
+ break;
+ }
+
+ work = list_first_entry(&dev->work_list,
+ struct vhost_work, node);
+ list_del_init(&work->node);
+ seq = work->queue_seq;
+
+ if (prev_mm != dev->mm) {
+ if (prev_mm)
+ unuse_mm(prev_mm);
+ prev_mm = dev->mm;
+ use_mm(prev_mm);
+ }
+ spin_unlock(&dev->work_lock);
+
+ if (work) {
+ work->fn(work);
+ spin_lock_irq(&dev->work_lock);
+ work->done_seq = seq;
+ if (work->flushing)
+ wake_up_all(&work->done);
+ spin_unlock_irq(&dev->work_lock);
+ }
+ }
+
+ if (prev_mm)
+ unuse_mm(prev_mm);
+ set_fs(oldfs);
+}
+
void vhost_dev_init(struct vhost_dev *dev,
struct vhost_virtqueue **vqs, int nvqs)
{
@@ -386,6 +439,10 @@ void vhost_dev_init(struct vhost_dev *dev,
spin_lock_init(&dev->work_lock);
INIT_LIST_HEAD(&dev->work_list);
dev->worker = NULL;
+ dev->qworker = NULL;
+
+ if (cmwq_worker)
+ INIT_WORK(&dev->qwork, vhost_wq_worker);
for (i = 0; i < dev->nvqs; ++i) {
vq = dev->vqs[i];
@@ -445,7 +502,8 @@ EXPORT_SYMBOL_GPL(vhost_dev_has_owner);
/* Caller should have device mutex */
long vhost_dev_set_owner(struct vhost_dev *dev)
{
- struct task_struct *worker;
+ struct task_struct *worker = NULL;
+ struct workqueue_struct *qworker;
int err;
/* Is there an owner already? */
@@ -456,18 +514,31 @@ long vhost_dev_set_owner(struct vhost_dev *dev)
/* No owner, become one */
dev->mm = get_task_mm(current);
- worker = kthread_create(vhost_worker, dev, "vhost-%d", current->pid);
- if (IS_ERR(worker)) {
- err = PTR_ERR(worker);
- goto err_worker;
- }
+ if (cmwq_worker) {
+ qworker = alloc_workqueue("vhost-wq-%d",
+ WQ_UNBOUND|WQ_CGROUPS,
+ 0, current->pid);
+ if (!qworker) {
+ err = -ENOMEM;
+ goto err_worker;
+ }
+ dev->qworker = qworker;
+ } else {
+ worker = kthread_create(vhost_worker, dev,
+ "vhost-%d", current->pid);
+ if (IS_ERR(worker)) {
+ err = PTR_ERR(worker);
+ goto err_worker;
+ }
- dev->worker = worker;
- wake_up_process(worker); /* avoid contributing to loadavg */
+ dev->worker = worker;
+ /* avoid contributing to loadavg */
+ wake_up_process(worker);
- err = vhost_attach_cgroups(dev);
- if (err)
- goto err_cgroup;
+ err = vhost_attach_cgroups(dev);
+ if (err)
+ goto err_cgroup;
+ }
err = vhost_dev_alloc_iovecs(dev);
if (err)
@@ -475,7 +546,8 @@ long vhost_dev_set_owner(struct vhost_dev *dev)
return 0;
err_cgroup:
- kthread_stop(worker);
+ if (worker)
+ kthread_stop(worker);
dev->worker = NULL;
err_worker:
if (dev->mm)
@@ -556,6 +628,11 @@ void vhost_dev_cleanup(struct vhost_dev *dev, bool locked)
kthread_stop(dev->worker);
dev->worker = NULL;
}
+ if (dev->qworker) {
+ /* destroy does flush */
+ destroy_workqueue(dev->qworker);
+ dev->qworker = NULL;
+ }
if (dev->mm)
mmput(dev->mm);
dev->mm = NULL;
diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
index d3f7674..e2ce0c3 100644
--- a/drivers/vhost/vhost.h
+++ b/drivers/vhost/vhost.h
@@ -127,6 +127,8 @@ struct vhost_dev {
spinlock_t work_lock;
struct list_head work_list;
struct task_struct *worker;
+ struct workqueue_struct *qworker;
+ struct work_struct qwork;
};
void vhost_dev_init(struct vhost_dev *, struct vhost_virtqueue **vqs, int nvqs);
--
2.5.0
--
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