Re: [PATCH 2/2] vhost-net: revert vhost_exceeds_maxpend logic to its original
From: Jason Wang <jasowang@redhat.com>
Date: 2017-08-21 03:06:33
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kvm, virtualization
On 2017年08月19日 14:41, Koichiro Den wrote:
To depend on vq.num and the usage of VHOST_MAX_PEND is not succinct and in some case unexpected, so revert its logic part only.
Hi: Could you explain a little bit more on the case that is was not sufficent? Thanks
quoted hunk ↗ jump to hunk
Signed-off-by: Koichiro Den <redacted> --- drivers/vhost/net.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c index 06d044862e58..99cf99b308a7 100644 --- a/drivers/vhost/net.c +++ b/drivers/vhost/net.c@@ -433,11 +433,15 @@ static int vhost_net_tx_get_vq_desc(struct vhost_net *net, static bool vhost_exceeds_maxpend(struct vhost_net *net) { + int num_pends; struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_TX]; struct vhost_virtqueue *vq = &nvq->vq; - return (nvq->upend_idx + vq->num - VHOST_MAX_PEND) % UIO_MAXIOV - == nvq->done_idx; + num_pends = likely(nvq->upend_idx >= nvq->done_idx) ? + (nvq->upend_idx - nvq->done_idx) : + (nvq->upend_idx + UIO_MAXIOV - nvq->done_idx); + + return num_pends > VHOST_MAX_PEND; } /* Expects to be always run from workqueue - which acts as
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