diff options
Diffstat (limited to 'drivers/vhost/net.c')
| -rw-r--r-- | drivers/vhost/net.c | 47 |
1 files changed, 26 insertions, 21 deletions
diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c index 9a68409580d5..a0fa5de210cf 100644 --- a/drivers/vhost/net.c +++ b/drivers/vhost/net.c @@ -70,7 +70,12 @@ enum { }; struct vhost_net_ubuf_ref { - struct kref kref; + /* refcount follows semantics similar to kref: + * 0: object is released + * 1: no outstanding ubufs + * >1: outstanding ubufs + */ + atomic_t refcount; wait_queue_head_t wait; struct vhost_virtqueue *vq; }; @@ -116,14 +121,6 @@ static void vhost_net_enable_zcopy(int vq) vhost_net_zcopy_mask |= 0x1 << vq; } -static void vhost_net_zerocopy_done_signal(struct kref *kref) -{ - struct vhost_net_ubuf_ref *ubufs; - - ubufs = container_of(kref, struct vhost_net_ubuf_ref, kref); - wake_up(&ubufs->wait); -} - static struct vhost_net_ubuf_ref * vhost_net_ubuf_alloc(struct vhost_virtqueue *vq, bool zcopy) { @@ -134,21 +131,24 @@ vhost_net_ubuf_alloc(struct vhost_virtqueue *vq, bool zcopy) ubufs = kmalloc(sizeof(*ubufs), GFP_KERNEL); if (!ubufs) return ERR_PTR(-ENOMEM); - kref_init(&ubufs->kref); + atomic_set(&ubufs->refcount, 1); init_waitqueue_head(&ubufs->wait); ubufs->vq = vq; return ubufs; } -static void vhost_net_ubuf_put(struct vhost_net_ubuf_ref *ubufs) +static int vhost_net_ubuf_put(struct vhost_net_ubuf_ref *ubufs) { - kref_put(&ubufs->kref, vhost_net_zerocopy_done_signal); + int r = atomic_sub_return(1, &ubufs->refcount); + if (unlikely(!r)) + wake_up(&ubufs->wait); + return r; } static void vhost_net_ubuf_put_and_wait(struct vhost_net_ubuf_ref *ubufs) { - kref_put(&ubufs->kref, vhost_net_zerocopy_done_signal); - wait_event(ubufs->wait, !atomic_read(&ubufs->kref.refcount)); + vhost_net_ubuf_put(ubufs); + wait_event(ubufs->wait, !atomic_read(&ubufs->refcount)); } static void vhost_net_ubuf_put_wait_and_free(struct vhost_net_ubuf_ref *ubufs) @@ -306,23 +306,26 @@ static void vhost_zerocopy_callback(struct ubuf_info *ubuf, bool success) { struct vhost_net_ubuf_ref *ubufs = ubuf->ctx; struct vhost_virtqueue *vq = ubufs->vq; - int cnt = atomic_read(&ubufs->kref.refcount); + int cnt; + + rcu_read_lock_bh(); /* set len to mark this desc buffers done DMA */ vq->heads[ubuf->desc].len = success ? VHOST_DMA_DONE_LEN : VHOST_DMA_FAILED_LEN; - vhost_net_ubuf_put(ubufs); + cnt = vhost_net_ubuf_put(ubufs); /* * Trigger polling thread if guest stopped submitting new buffers: - * in this case, the refcount after decrement will eventually reach 1 - * so here it is 2. + * in this case, the refcount after decrement will eventually reach 1. * We also trigger polling periodically after each 16 packets * (the value 16 here is more or less arbitrary, it's tuned to trigger * less than 10% of times). */ - if (cnt <= 2 || !(cnt % 16)) + if (cnt <= 1 || !(cnt % 16)) vhost_poll_queue(&vq->poll); + + rcu_read_unlock_bh(); } /* Expects to be always run from workqueue - which acts as @@ -420,7 +423,7 @@ static void handle_tx(struct vhost_net *net) msg.msg_control = ubuf; msg.msg_controllen = sizeof(ubuf); ubufs = nvq->ubufs; - kref_get(&ubufs->kref); + atomic_inc(&ubufs->refcount); nvq->upend_idx = (nvq->upend_idx + 1) % UIO_MAXIOV; } else { msg.msg_control = NULL; @@ -780,7 +783,7 @@ static void vhost_net_flush(struct vhost_net *n) vhost_net_ubuf_put_and_wait(n->vqs[VHOST_NET_VQ_TX].ubufs); mutex_lock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex); n->tx_flush = false; - kref_init(&n->vqs[VHOST_NET_VQ_TX].ubufs->kref); + atomic_set(&n->vqs[VHOST_NET_VQ_TX].ubufs->refcount, 1); mutex_unlock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex); } } @@ -800,6 +803,8 @@ static int vhost_net_release(struct inode *inode, struct file *f) fput(tx_sock->file); if (rx_sock) fput(rx_sock->file); + /* Make sure no callbacks are outstanding */ + synchronize_rcu_bh(); /* We do an extra flush before freeing memory, * since jobs can re-queue themselves. */ vhost_net_flush(n); |