search for: virtqueue_enable_cb

...n 10/15/2014 05:34 PM, Michael S. Tsirkin wrote: >>> On Wed, Oct 15, 2014 at 03:25:25PM +0800, Jason Wang wrote: >>>> This patch checks the new event idx to make sure used event idx never >>>> goes back. This is used to synchronize the calls between >>>> virtqueue_enable_cb_delayed() and virtqueue_enable_cb(). >>>> >>>> Cc: Rusty Russell <rusty at rustcorp.com.au> >>>> Cc: Michael S. Tsirkin <mst at redhat.com> >>>> Signed-off-by: Jason Wang <jasowang at redhat.com> >>> the implication being th...

...n 10/15/2014 05:34 PM, Michael S. Tsirkin wrote: >>> On Wed, Oct 15, 2014 at 03:25:25PM +0800, Jason Wang wrote: >>>> This patch checks the new event idx to make sure used event idx never >>>> goes back. This is used to synchronize the calls between >>>> virtqueue_enable_cb_delayed() and virtqueue_enable_cb(). >>>> >>>> Cc: Rusty Russell <rusty at rustcorp.com.au> >>>> Cc: Michael S. Tsirkin <mst at redhat.com> >>>> Signed-off-by: Jason Wang <jasowang at redhat.com> >>> the implication being th...

...) diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c index 5217baf..37d58f8 100644 --- a/drivers/virtio/virtio_ring.c +++ b/drivers/virtio/virtio_ring.c @@ -607,19 +607,21 @@ void virtqueue_disable_cb(struct virtqueue *_vq) EXPORT_SYMBOL_GPL(virtqueue_disable_cb); /** - * virtqueue_enable_cb - restart callbacks after disable_cb. + * virtqueue_enable_cb_prepare - restart callbacks after disable_cb * @vq: the struct virtqueue we're talking about. * - * This re-enables callbacks; it returns "false" if there are pending - * buffers in the queue, to detect a possible race...

...) diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c index 5217baf..37d58f8 100644 --- a/drivers/virtio/virtio_ring.c +++ b/drivers/virtio/virtio_ring.c @@ -607,19 +607,21 @@ void virtqueue_disable_cb(struct virtqueue *_vq) EXPORT_SYMBOL_GPL(virtqueue_disable_cb); /** - * virtqueue_enable_cb - restart callbacks after disable_cb. + * virtqueue_enable_cb_prepare - restart callbacks after disable_cb * @vq: the struct virtqueue we're talking about. * - * This re-enables callbacks; it returns "false" if there are pending - * buffers in the queue, to detect a possible race...

On 10/15/2014 05:34 PM, Michael S. Tsirkin wrote: > On Wed, Oct 15, 2014 at 03:25:25PM +0800, Jason Wang wrote: >> This patch checks the new event idx to make sure used event idx never >> goes back. This is used to synchronize the calls between >> virtqueue_enable_cb_delayed() and virtqueue_enable_cb(). >> >> Cc: Rusty Russell <rusty at rustcorp.com.au> >> Cc: Michael S. Tsirkin <mst at redhat.com> >> Signed-off-by: Jason Wang <jasowang at redhat.com> > the implication being that moving event idx back might cause som...

On 10/15/2014 05:34 PM, Michael S. Tsirkin wrote: > On Wed, Oct 15, 2014 at 03:25:25PM +0800, Jason Wang wrote: >> This patch checks the new event idx to make sure used event idx never >> goes back. This is used to synchronize the calls between >> virtqueue_enable_cb_delayed() and virtqueue_enable_cb(). >> >> Cc: Rusty Russell <rusty at rustcorp.com.au> >> Cc: Michael S. Tsirkin <mst at redhat.com> >> Signed-off-by: Jason Wang <jasowang at redhat.com> > the implication being that moving event idx back might cause som...

...ing NAPI wrong due to this. /** * vringh_notify_enable_kern - we want to know if something changes. * @vrh: the vring. * * This always enables notifications, but returns true if there are * now more buffers available in the vring. */ bool vringh_notify_enable_kern(struct vringh *vrh) /** * virtqueue_enable_cb - restart callbacks after disable_cb. * @vq: the struct virtqueue we're talking about. * * This re-enables callbacks; it returns "false" if there are pending * buffers in the queue, .... */ bool virtqueue_enable_cb(struct virtqueue *_vq) Regards. Sjur

...ing NAPI wrong due to this. /** * vringh_notify_enable_kern - we want to know if something changes. * @vrh: the vring. * * This always enables notifications, but returns true if there are * now more buffers available in the vring. */ bool vringh_notify_enable_kern(struct vringh *vrh) /** * virtqueue_enable_cb - restart callbacks after disable_cb. * @vq: the struct virtqueue we're talking about. * * This re-enables callbacks; it returns "false" if there are pending * buffers in the queue, .... */ bool virtqueue_enable_cb(struct virtqueue *_vq) Regards. Sjur

...->idx - last_used_idx) * 3 / 4; > > This is ok now since we only try to enable the delayed callbacks when > the queue is about to be full. This may not work well when there is > only one pending buffer in the virtqueue (this may be the case after > tx interrupt was enabled). Since virtqueue_enable_cb() will return > false which may cause unnecessary triggering of napis. This patch > correct this by only calculate the four thirds when bufs is not one. I mildly prefer to avoid the branch, by changing the calculation like so: /* Set bufs >= 1, even if there's only one pendin...

...->idx - last_used_idx) * 3 / 4; > > This is ok now since we only try to enable the delayed callbacks when > the queue is about to be full. This may not work well when there is > only one pending buffer in the virtqueue (this may be the case after > tx interrupt was enabled). Since virtqueue_enable_cb() will return > false which may cause unnecessary triggering of napis. This patch > correct this by only calculate the four thirds when bufs is not one. I mildly prefer to avoid the branch, by changing the calculation like so: /* Set bufs >= 1, even if there's only one pendin...

...rote: > On 10/15/2014 05:34 PM, Michael S. Tsirkin wrote: > > On Wed, Oct 15, 2014 at 03:25:25PM +0800, Jason Wang wrote: > >> This patch checks the new event idx to make sure used event idx never > >> goes back. This is used to synchronize the calls between > >> virtqueue_enable_cb_delayed() and virtqueue_enable_cb(). > >> > >> Cc: Rusty Russell <rusty at rustcorp.com.au> > >> Cc: Michael S. Tsirkin <mst at redhat.com> > >> Signed-off-by: Jason Wang <jasowang at redhat.com> > > the implication being that moving event...

...* 3 / 4; > > > > This is ok now since we only try to enable the delayed callbacks when > > the queue is about to be full. This may not work well when there is > > only one pending buffer in the virtqueue (this may be the case after > > tx interrupt was enabled). Since virtqueue_enable_cb() will return > > false which may cause unnecessary triggering of napis. This patch > > correct this by only calculate the four thirds when bufs is not one. > > I mildly prefer to avoid the branch, by changing the calculation like > so: > > /* Set bufs >= 1,...

...* 3 / 4; > > > > This is ok now since we only try to enable the delayed callbacks when > > the queue is about to be full. This may not work well when there is > > only one pending buffer in the virtqueue (this may be the case after > > tx interrupt was enabled). Since virtqueue_enable_cb() will return > > false which may cause unnecessary triggering of napis. This patch > > correct this by only calculate the four thirds when bufs is not one. > > I mildly prefer to avoid the branch, by changing the calculation like > so: > > /* Set bufs >= 1,...

...M, Michael S. Tsirkin wrote: > >>> On Wed, Oct 15, 2014 at 03:25:25PM +0800, Jason Wang wrote: > >>>> This patch checks the new event idx to make sure used event idx never > >>>> goes back. This is used to synchronize the calls between > >>>> virtqueue_enable_cb_delayed() and virtqueue_enable_cb(). > >>>> > >>>> Cc: Rusty Russell <rusty at rustcorp.com.au> > >>>> Cc: Michael S. Tsirkin <mst at redhat.com> > >>>> Signed-off-by: Jason Wang <jasowang at redhat.com> > >>>...

...) diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c index 5217baf..37d58f8 100644 --- a/drivers/virtio/virtio_ring.c +++ b/drivers/virtio/virtio_ring.c @@ -607,19 +607,21 @@ void virtqueue_disable_cb(struct virtqueue *_vq) EXPORT_SYMBOL_GPL(virtqueue_disable_cb); /** - * virtqueue_enable_cb - restart callbacks after disable_cb. + * virtqueue_enable_cb_prepare - restart callbacks after disable_cb * @vq: the struct virtqueue we're talking about. * - * This re-enables callbacks; it returns "false" if there are pending - * buffers in the queue, to detect a possible race...

...) diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c index 5217baf..37d58f8 100644 --- a/drivers/virtio/virtio_ring.c +++ b/drivers/virtio/virtio_ring.c @@ -607,19 +607,21 @@ void virtqueue_disable_cb(struct virtqueue *_vq) EXPORT_SYMBOL_GPL(virtqueue_disable_cb); /** - * virtqueue_enable_cb - restart callbacks after disable_cb. + * virtqueue_enable_cb_prepare - restart callbacks after disable_cb * @vq: the struct virtqueue we're talking about. * - * This re-enables callbacks; it returns "false" if there are pending - * buffers in the queue, to detect a possible race...

...tly does: bufs = (avail->idx - last_used_idx) * 3 / 4; This is ok now since we only try to enable the delayed callbacks when the queue is about to be full. This may not work well when there is only one pending buffer in the virtqueue (this may be the case after tx interrupt was enabled). Since virtqueue_enable_cb() will return false which may cause unnecessary triggering of napis. This patch correct this by only calculate the four thirds when bufs is not one. Signed-off-by: Jason Wang <jasowang at redhat.com> --- drivers/virtio/virtio_ring.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)...

...tly does: bufs = (avail->idx - last_used_idx) * 3 / 4; This is ok now since we only try to enable the delayed callbacks when the queue is about to be full. This may not work well when there is only one pending buffer in the virtqueue (this may be the case after tx interrupt was enabled). Since virtqueue_enable_cb() will return false which may cause unnecessary triggering of napis. This patch correct this by only calculate the four thirds when bufs is not one. Signed-off-by: Jason Wang <jasowang at redhat.com> --- drivers/virtio/virtio_ring.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)...

On Fri, 2013-07-12 at 23:13 +0200, Wolfram Gloger wrote: > Hi, > > Today I merged M. Tsirkin's patch v2 "virtio_net: fix race in RX VQ > processing": > > http://lkml.indiana.edu/hypermail/linux/kernel/1307.1/00503.html > > into 3.2.48 and lightly tested the result (vhost-net, virtio-disk > and 9pfs using virtio). This sounds like it could be suitable

On Fri, 2013-07-12 at 23:13 +0200, Wolfram Gloger wrote: > Hi, > > Today I merged M. Tsirkin's patch v2 "virtio_net: fix race in RX VQ > processing": > > http://lkml.indiana.edu/hypermail/linux/kernel/1307.1/00503.html > > into 3.2.48 and lightly tested the result (vhost-net, virtio-disk > and 9pfs using virtio). This sounds like it could be suitable