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authorJason Wang <jasowang@redhat.com>2013-09-02 16:41:00 +0800
committerDavid S. Miller <davem@davemloft.net>2013-09-03 22:46:57 -0400
commit19c73b3e08d16ee923f3962df4abf6205127896a (patch)
treec41a951349c70e683ab84028facd68d97d9aab9a
parentce21a02913dc79205485637b6e0927a4c800c4a4 (diff)
downloadlinux-19c73b3e08d16ee923f3962df4abf6205127896a.tar.bz2
vhost_net: poll vhost queue after marking DMA is done
We used to poll vhost queue before making DMA is done, this is racy if vhost thread were waked up before marking DMA is done which can result the signal to be missed. Fix this by always polling the vhost thread before DMA is done. Signed-off-by: Jason Wang <jasowang@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--drivers/vhost/net.c9
1 files changed, 5 insertions, 4 deletions
diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index 3f89dea297a3..8e9dc554b1ef 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -308,6 +308,11 @@ static void vhost_zerocopy_callback(struct ubuf_info *ubuf, bool success)
struct vhost_virtqueue *vq = ubufs->vq;
int cnt = atomic_read(&ubufs->kref.refcount);
+ /* 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);
+
/*
* Trigger polling thread if guest stopped submitting new buffers:
* in this case, the refcount after decrement will eventually reach 1
@@ -318,10 +323,6 @@ static void vhost_zerocopy_callback(struct ubuf_info *ubuf, bool success)
*/
if (cnt <= 2 || !(cnt % 16))
vhost_poll_queue(&vq->poll);
- /* 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);
}
/* Expects to be always run from workqueue - which acts as