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Diffstat (limited to 'drivers/vhost/net.c')
-rw-r--r--drivers/vhost/net.c47
1 files changed, 26 insertions, 21 deletions
diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index 9a68409..a0fa5de 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);
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