vduse: Fix race condition between resetting and irq injecting

The interrupt might be triggered after a reset since there is
no synchronization between resetting and irq injecting. And it
might break something if the interrupt is delayed until a new
round of device initialization.

Fixes: c8a6153b6c59 ("vduse: Introduce VDUSE - vDPA Device in Userspace")
Signed-off-by: Xie Yongji <xieyongji@bytedance.com>
Link: https://lore.kernel.org/r/20210929083050.88-1-xieyongji@bytedance.com
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c
index cefb301b2ee48a5f941dade64acc4a32c3c5ea93..841667a896dd020da0481b07395a23692fc1fedd 100644 (file)
--- a/drivers/vdpa/vdpa_user/vduse_dev.c
+++ b/drivers/vdpa/vdpa_user/vduse_dev.c
@@ -80,6 +80,7 @@ struct vduse_dev {
        struct vdpa_callback config_cb;
        struct work_struct inject;
        spinlock_t irq_lock;
+       struct rw_semaphore rwsem;
        int minor;
        bool broken;
        bool connected;
@@ -410,6 +411,8 @@ static void vduse_dev_reset(struct vduse_dev *dev)
        if (domain->bounce_map)
                vduse_domain_reset_bounce_map(domain);
 
+       down_write(&dev->rwsem);
+
        dev->status = 0;
        dev->driver_features = 0;
        dev->generation++;
@@ -443,6 +446,8 @@ static void vduse_dev_reset(struct vduse_dev *dev)
                flush_work(&vq->inject);
                flush_work(&vq->kick);
        }
+
+       up_write(&dev->rwsem);
 }
 
 static int vduse_vdpa_set_vq_address(struct vdpa_device *vdpa, u16 idx,
@@ -885,6 +890,23 @@ static void vduse_vq_irq_inject(struct work_struct *work)
        spin_unlock_irq(&vq->irq_lock);
 }
 
+static int vduse_dev_queue_irq_work(struct vduse_dev *dev,
+                                   struct work_struct *irq_work)
+{
+       int ret = -EINVAL;
+
+       down_read(&dev->rwsem);
+       if (!(dev->status & VIRTIO_CONFIG_S_DRIVER_OK))
+               goto unlock;
+
+       ret = 0;
+       queue_work(vduse_irq_wq, irq_work);
+unlock:
+       up_read(&dev->rwsem);
+
+       return ret;
+}
+
 static long vduse_dev_ioctl(struct file *file, unsigned int cmd,
                            unsigned long arg)
 {
@@ -966,12 +988,7 @@ static long vduse_dev_ioctl(struct file *file, unsigned int cmd,
                break;
        }
        case VDUSE_DEV_INJECT_CONFIG_IRQ:
-               ret = -EINVAL;
-               if (!(dev->status & VIRTIO_CONFIG_S_DRIVER_OK))
-                       break;
-
-               ret = 0;
-               queue_work(vduse_irq_wq, &dev->inject);
+               ret = vduse_dev_queue_irq_work(dev, &dev->inject);
                break;
        case VDUSE_VQ_SETUP: {
                struct vduse_vq_config config;
@@ -1049,10 +1066,6 @@ static long vduse_dev_ioctl(struct file *file, unsigned int cmd,
        case VDUSE_VQ_INJECT_IRQ: {
                u32 index;
 
-               ret = -EINVAL;
-               if (!(dev->status & VIRTIO_CONFIG_S_DRIVER_OK))
-                       break;
-
                ret = -EFAULT;
                if (get_user(index, (u32 __user *)argp))
                        break;
@@ -1061,9 +1074,8 @@ static long vduse_dev_ioctl(struct file *file, unsigned int cmd,
                if (index >= dev->vq_num)
                        break;
 
-               ret = 0;
                index = array_index_nospec(index, dev->vq_num);
-               queue_work(vduse_irq_wq, &dev->vqs[index].inject);
+               ret = vduse_dev_queue_irq_work(dev, &dev->vqs[index].inject);
                break;
        }
        default:
@@ -1144,6 +1156,7 @@ static struct vduse_dev *vduse_dev_create(void)
        INIT_LIST_HEAD(&dev->send_list);
        INIT_LIST_HEAD(&dev->recv_list);
        spin_lock_init(&dev->irq_lock);
+       init_rwsem(&dev->rwsem);
 
        INIT_WORK(&dev->inject, vduse_dev_irq_inject);
        init_waitqueue_head(&dev->waitq);