From: Jason Wang <jasowang@redhat.com> To: mst@redhat.com, kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Cc: RAPOPORT@il.ibm.com, yang.zhang.wz@gmail.com, borntraeger@de.ibm.com, Jason Wang <jasowang@redhat.com> Subject: [PATCH V4 2/3] vhost: introduce vhost_vq_avail_empty() Date: Fri, 4 Mar 2016 06:24:52 -0500 [thread overview] Message-ID: <1457090693-55974-3-git-send-email-jasowang@redhat.com> (raw) In-Reply-To: <1457090693-55974-1-git-send-email-jasowang@redhat.com> This patch introduces a helper which will return true if we're sure that the available ring is empty for a specific vq. When we're not sure, e.g vq access failure, return false instead. This could be used for busy polling code to exit the busy loop. Signed-off-by: Jason Wang <jasowang@redhat.com> --- drivers/vhost/vhost.c | 14 ++++++++++++++ drivers/vhost/vhost.h | 1 + 2 files changed, 15 insertions(+) diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c index 90ac092..89301fd 100644 --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c @@ -1633,6 +1633,20 @@ void vhost_add_used_and_signal_n(struct vhost_dev *dev, } EXPORT_SYMBOL_GPL(vhost_add_used_and_signal_n); +/* return true if we're sure that avaiable ring is empty */ +bool vhost_vq_avail_empty(struct vhost_dev *dev, struct vhost_virtqueue *vq) +{ + __virtio16 avail_idx; + int r; + + r = __get_user(avail_idx, &vq->avail->idx); + if (r) + return false; + + return vhost16_to_cpu(vq, avail_idx) == vq->avail_idx; +} +EXPORT_SYMBOL_GPL(vhost_vq_avail_empty); + /* OK, now we need to know about added descriptors. */ bool vhost_enable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq) { diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h index 43284ad..a7a43f0 100644 --- a/drivers/vhost/vhost.h +++ b/drivers/vhost/vhost.h @@ -159,6 +159,7 @@ void vhost_add_used_and_signal_n(struct vhost_dev *, struct vhost_virtqueue *, struct vring_used_elem *heads, unsigned count); void vhost_signal(struct vhost_dev *, struct vhost_virtqueue *); void vhost_disable_notify(struct vhost_dev *, struct vhost_virtqueue *); +bool vhost_vq_avail_empty(struct vhost_dev *, struct vhost_virtqueue *); bool vhost_enable_notify(struct vhost_dev *, struct vhost_virtqueue *); int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log, -- 1.8.3.1
WARNING: multiple messages have this Message-ID (diff)
From: Jason Wang <jasowang@redhat.com> To: mst@redhat.com, kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Cc: yang.zhang.wz@gmail.com, borntraeger@de.ibm.com, RAPOPORT@il.ibm.com Subject: [PATCH V4 2/3] vhost: introduce vhost_vq_avail_empty() Date: Fri, 4 Mar 2016 06:24:52 -0500 [thread overview] Message-ID: <1457090693-55974-3-git-send-email-jasowang@redhat.com> (raw) In-Reply-To: <1457090693-55974-1-git-send-email-jasowang@redhat.com> This patch introduces a helper which will return true if we're sure that the available ring is empty for a specific vq. When we're not sure, e.g vq access failure, return false instead. This could be used for busy polling code to exit the busy loop. Signed-off-by: Jason Wang <jasowang@redhat.com> --- drivers/vhost/vhost.c | 14 ++++++++++++++ drivers/vhost/vhost.h | 1 + 2 files changed, 15 insertions(+) diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c index 90ac092..89301fd 100644 --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c @@ -1633,6 +1633,20 @@ void vhost_add_used_and_signal_n(struct vhost_dev *dev, } EXPORT_SYMBOL_GPL(vhost_add_used_and_signal_n); +/* return true if we're sure that avaiable ring is empty */ +bool vhost_vq_avail_empty(struct vhost_dev *dev, struct vhost_virtqueue *vq) +{ + __virtio16 avail_idx; + int r; + + r = __get_user(avail_idx, &vq->avail->idx); + if (r) + return false; + + return vhost16_to_cpu(vq, avail_idx) == vq->avail_idx; +} +EXPORT_SYMBOL_GPL(vhost_vq_avail_empty); + /* OK, now we need to know about added descriptors. */ bool vhost_enable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq) { diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h index 43284ad..a7a43f0 100644 --- a/drivers/vhost/vhost.h +++ b/drivers/vhost/vhost.h @@ -159,6 +159,7 @@ void vhost_add_used_and_signal_n(struct vhost_dev *, struct vhost_virtqueue *, struct vring_used_elem *heads, unsigned count); void vhost_signal(struct vhost_dev *, struct vhost_virtqueue *); void vhost_disable_notify(struct vhost_dev *, struct vhost_virtqueue *); +bool vhost_vq_avail_empty(struct vhost_dev *, struct vhost_virtqueue *); bool vhost_enable_notify(struct vhost_dev *, struct vhost_virtqueue *); int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log, -- 1.8.3.1
next prev parent reply other threads:[~2016-03-04 11:25 UTC|newest] Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top 2016-03-04 11:24 [PATCH V4 0/3] basic busy polling support for vhost_net Jason Wang 2016-03-04 11:24 ` Jason Wang 2016-03-04 11:24 ` [PATCH V4 1/3] vhost: introduce vhost_has_work() Jason Wang 2016-03-04 11:24 ` Jason Wang 2016-03-04 11:24 ` Jason Wang [this message] 2016-03-04 11:24 ` [PATCH V4 2/3] vhost: introduce vhost_vq_avail_empty() Jason Wang 2016-03-04 11:24 ` [PATCH V4 3/3] vhost_net: basic polling support Jason Wang 2016-03-04 11:24 ` Jason Wang 2016-03-09 19:26 ` [PATCH V4 0/3] basic busy polling support for vhost_net Greg Kurz 2016-03-09 19:26 ` Greg Kurz 2016-03-10 6:48 ` Michael Rapoport 2016-03-15 3:10 ` Jason Wang 2016-03-15 3:10 ` Jason Wang 2016-03-10 6:48 ` Michael Rapoport 2016-03-10 6:48 ` Michael Rapoport 2016-03-10 6:48 ` Michael Rapoport
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