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 <[email protected]> --- 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
