2023-03-29 07:36:46

by 黄杰

[permalink] [raw]
Subject: [PATCH v3] virtio_ring: interrupt disable flag updated to vq even with event_triggered is set

From: "huangjie.albert" <[email protected]>

in virtio_net, if we disable the napi_tx, when we triger a tx interrupt,
the vq->event_triggered will be set to true. It will no longer be set to
false. Unless we explicitly call virtqueue_enable_cb_delayed or
virtqueue_enable_cb_prepare.

If we disable the napi_tx, it will only be called when the tx ring
buffer is relatively small.

Because event_triggered is true. Therefore, VRING_AVAIL_F_NO_INTERRUPT or
VRING_PACKED_EVENT_FLAG_DISABLE will not be set. So we update
vring_used_event(&vq->split.vring) or vq->packed.vring.driver->off_wrap
every time we call virtqueue_get_buf_ctx.This bring more interruptions.

To summarize:
1) event_triggered was set to true in vring_interrupt()
2) after this nothing will happen for virtqueue_disable_cb() so
VRING_AVAIL_F_NO_INTERRUPT is not set in avail_flags_shadow
3) virtqueue_get_buf_ctx_split() will still think the cb is enabled
then it tries to publish new event

To fix:
update VRING_AVAIL_F_NO_INTERRUPT or VRING_PACKED_EVENT_FLAG_DISABLE to vq
when we call virtqueue_disable_cb even the event_triggered is set to true.

Tested with iperf:
iperf3 tcp stream:
vm1 -----------------> vm2
vm2 just receives tcp data stream from vm1, and sends the ack to vm1,
there are many tx interrupts in vm2.
but without event_triggered there are just a few tx interrupts.

v2->v3:
-update the interrupt disable flag even with the event_triggered is set,
-instead of checking whether event_triggered is set in
-virtqueue_get_buf_ctx_{packed/split}, will cause the drivers which have
-not called virtqueue_{enable/disable}_cb to miss notifications.

Fixes: 8d622d21d248 ("virtio: fix up virtio_disable_cb")
Signed-off-by: huangjie.albert <[email protected]>
Signed-off-by: Michael S. Tsirkin <[email protected]>
Signed-off-by: Jason Wang <[email protected]>
---
drivers/virtio/virtio_ring.c | 24 +++++++++++++++++-------
1 file changed, 17 insertions(+), 7 deletions(-)

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 307e139cb11d..ad74463a48ee 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -812,6 +812,14 @@ static void virtqueue_disable_cb_split(struct virtqueue *_vq)

if (!(vq->split.avail_flags_shadow & VRING_AVAIL_F_NO_INTERRUPT)) {
vq->split.avail_flags_shadow |= VRING_AVAIL_F_NO_INTERRUPT;
+
+ /*
+ * If device triggered an event already it won't trigger one again:
+ * no need to disable.
+ */
+ if (vq->event_triggered)
+ return;
+
if (vq->event)
/* TODO: this is a hack. Figure out a cleaner value to write. */
vring_used_event(&vq->split.vring) = 0x0;
@@ -1544,8 +1552,16 @@ static void virtqueue_disable_cb_packed(struct virtqueue *_vq)
{
struct vring_virtqueue *vq = to_vvq(_vq);

- if (vq->packed.event_flags_shadow != VRING_PACKED_EVENT_FLAG_DISABLE) {
+ if (!(vq->packed.event_flags_shadow & VRING_PACKED_EVENT_FLAG_DISABLE)) {
vq->packed.event_flags_shadow = VRING_PACKED_EVENT_FLAG_DISABLE;
+
+ /*
+ * If device triggered an event already it won't trigger one again:
+ * no need to disable.
+ */
+ if (vq->event_triggered)
+ return;
+
vq->packed.vring.driver->flags =
cpu_to_le16(vq->packed.event_flags_shadow);
}
@@ -2063,12 +2079,6 @@ void virtqueue_disable_cb(struct virtqueue *_vq)
{
struct vring_virtqueue *vq = to_vvq(_vq);

- /* If device triggered an event already it won't trigger one again:
- * no need to disable.
- */
- if (vq->event_triggered)
- return;
-
if (vq->packed_ring)
virtqueue_disable_cb_packed(_vq);
else
--
2.31.1


2023-03-29 09:37:54

by Xuan Zhuo

[permalink] [raw]
Subject: Re: [PATCH v3] virtio_ring: interrupt disable flag updated to vq even with event_triggered is set

On Wed, 29 Mar 2023 15:28:41 +0800, Albert Huang <[email protected]> wrote:
> From: "huangjie.albert" <[email protected]>
>
> in virtio_net, if we disable the napi_tx, when we triger a tx interrupt,
> the vq->event_triggered will be set to true. It will no longer be set to
> false. Unless we explicitly call virtqueue_enable_cb_delayed or
> virtqueue_enable_cb_prepare.
>
> If we disable the napi_tx, it will only be called when the tx ring
> buffer is relatively small.
>
> Because event_triggered is true. Therefore, VRING_AVAIL_F_NO_INTERRUPT or
> VRING_PACKED_EVENT_FLAG_DISABLE will not be set. So we update
> vring_used_event(&vq->split.vring) or vq->packed.vring.driver->off_wrap
> every time we call virtqueue_get_buf_ctx.This bring more interruptions.
>
> To summarize:
> 1) event_triggered was set to true in vring_interrupt()
> 2) after this nothing will happen for virtqueue_disable_cb() so
> VRING_AVAIL_F_NO_INTERRUPT is not set in avail_flags_shadow
> 3) virtqueue_get_buf_ctx_split() will still think the cb is enabled
> then it tries to publish new event
>
> To fix:
> update VRING_AVAIL_F_NO_INTERRUPT or VRING_PACKED_EVENT_FLAG_DISABLE to vq
> when we call virtqueue_disable_cb even the event_triggered is set to true.
>
> Tested with iperf:
> iperf3 tcp stream:
> vm1 -----------------> vm2
> vm2 just receives tcp data stream from vm1, and sends the ack to vm1,
> there are many tx interrupts in vm2.
> but without event_triggered there are just a few tx interrupts.
>
> v2->v3:
> -update the interrupt disable flag even with the event_triggered is set,
> -instead of checking whether event_triggered is set in
> -virtqueue_get_buf_ctx_{packed/split}, will cause the drivers which have
> -not called virtqueue_{enable/disable}_cb to miss notifications.
>
> Fixes: 8d622d21d248 ("virtio: fix up virtio_disable_cb")
> Signed-off-by: huangjie.albert <[email protected]>
> Signed-off-by: Michael S. Tsirkin <[email protected]>
> Signed-off-by: Jason Wang <[email protected]>
> ---
> drivers/virtio/virtio_ring.c | 24 +++++++++++++++++-------
> 1 file changed, 17 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
> index 307e139cb11d..ad74463a48ee 100644
> --- a/drivers/virtio/virtio_ring.c
> +++ b/drivers/virtio/virtio_ring.c
> @@ -812,6 +812,14 @@ static void virtqueue_disable_cb_split(struct virtqueue *_vq)
>
> if (!(vq->split.avail_flags_shadow & VRING_AVAIL_F_NO_INTERRUPT)) {
> vq->split.avail_flags_shadow |= VRING_AVAIL_F_NO_INTERRUPT;
> +
> + /*
> + * If device triggered an event already it won't trigger one again:
> + * no need to disable.
> + */
> + if (vq->event_triggered)
> + return;
> +
> if (vq->event)
> /* TODO: this is a hack. Figure out a cleaner value to write. */
> vring_used_event(&vq->split.vring) = 0x0;
> @@ -1544,8 +1552,16 @@ static void virtqueue_disable_cb_packed(struct virtqueue *_vq)
> {
> struct vring_virtqueue *vq = to_vvq(_vq);
>
> - if (vq->packed.event_flags_shadow != VRING_PACKED_EVENT_FLAG_DISABLE) {
> + if (!(vq->packed.event_flags_shadow & VRING_PACKED_EVENT_FLAG_DISABLE)) {

This seems to be another problem.

Thanks.


> vq->packed.event_flags_shadow = VRING_PACKED_EVENT_FLAG_DISABLE;
> +
> + /*
> + * If device triggered an event already it won't trigger one again:
> + * no need to disable.
> + */
> + if (vq->event_triggered)
> + return;
> +
> vq->packed.vring.driver->flags =
> cpu_to_le16(vq->packed.event_flags_shadow);
> }
> @@ -2063,12 +2079,6 @@ void virtqueue_disable_cb(struct virtqueue *_vq)
> {
> struct vring_virtqueue *vq = to_vvq(_vq);
>
> - /* If device triggered an event already it won't trigger one again:
> - * no need to disable.
> - */
> - if (vq->event_triggered)
> - return;
> -
> if (vq->packed_ring)
> virtqueue_disable_cb_packed(_vq);
> else
> --
> 2.31.1
>

2023-03-29 09:41:15

by 黄杰

[permalink] [raw]
Subject: Re: [External] Re: [PATCH v3] virtio_ring: interrupt disable flag updated to vq even with event_triggered is set

Xuan Zhuo <[email protected]> 于2023年3月29日周三 17:27写道:
>
> On Wed, 29 Mar 2023 15:28:41 +0800, Albert Huang <[email protected]> wrote:
> > From: "huangjie.albert" <[email protected]>
> >
> > in virtio_net, if we disable the napi_tx, when we triger a tx interrupt,
> > the vq->event_triggered will be set to true. It will no longer be set to
> > false. Unless we explicitly call virtqueue_enable_cb_delayed or
> > virtqueue_enable_cb_prepare.
> >
> > If we disable the napi_tx, it will only be called when the tx ring
> > buffer is relatively small.
> >
> > Because event_triggered is true. Therefore, VRING_AVAIL_F_NO_INTERRUPT or
> > VRING_PACKED_EVENT_FLAG_DISABLE will not be set. So we update
> > vring_used_event(&vq->split.vring) or vq->packed.vring.driver->off_wrap
> > every time we call virtqueue_get_buf_ctx.This bring more interruptions.
> >
> > To summarize:
> > 1) event_triggered was set to true in vring_interrupt()
> > 2) after this nothing will happen for virtqueue_disable_cb() so
> > VRING_AVAIL_F_NO_INTERRUPT is not set in avail_flags_shadow
> > 3) virtqueue_get_buf_ctx_split() will still think the cb is enabled
> > then it tries to publish new event
> >
> > To fix:
> > update VRING_AVAIL_F_NO_INTERRUPT or VRING_PACKED_EVENT_FLAG_DISABLE to vq
> > when we call virtqueue_disable_cb even the event_triggered is set to true.
> >
> > Tested with iperf:
> > iperf3 tcp stream:
> > vm1 -----------------> vm2
> > vm2 just receives tcp data stream from vm1, and sends the ack to vm1,
> > there are many tx interrupts in vm2.
> > but without event_triggered there are just a few tx interrupts.
> >
> > v2->v3:
> > -update the interrupt disable flag even with the event_triggered is set,
> > -instead of checking whether event_triggered is set in
> > -virtqueue_get_buf_ctx_{packed/split}, will cause the drivers which have
> > -not called virtqueue_{enable/disable}_cb to miss notifications.
> >
> > Fixes: 8d622d21d248 ("virtio: fix up virtio_disable_cb")
> > Signed-off-by: huangjie.albert <[email protected]>
> > Signed-off-by: Michael S. Tsirkin <[email protected]>
> > Signed-off-by: Jason Wang <[email protected]>
> > ---
> > drivers/virtio/virtio_ring.c | 24 +++++++++++++++++-------
> > 1 file changed, 17 insertions(+), 7 deletions(-)
> >
> > diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
> > index 307e139cb11d..ad74463a48ee 100644
> > --- a/drivers/virtio/virtio_ring.c
> > +++ b/drivers/virtio/virtio_ring.c
> > @@ -812,6 +812,14 @@ static void virtqueue_disable_cb_split(struct virtqueue *_vq)
> >
> > if (!(vq->split.avail_flags_shadow & VRING_AVAIL_F_NO_INTERRUPT)) {
> > vq->split.avail_flags_shadow |= VRING_AVAIL_F_NO_INTERRUPT;
> > +
> > + /*
> > + * If device triggered an event already it won't trigger one again:
> > + * no need to disable.
> > + */
> > + if (vq->event_triggered)
> > + return;
> > +
> > if (vq->event)
> > /* TODO: this is a hack. Figure out a cleaner value to write. */
> > vring_used_event(&vq->split.vring) = 0x0;
> > @@ -1544,8 +1552,16 @@ static void virtqueue_disable_cb_packed(struct virtqueue *_vq)
> > {
> > struct vring_virtqueue *vq = to_vvq(_vq);
> >
> > - if (vq->packed.event_flags_shadow != VRING_PACKED_EVENT_FLAG_DISABLE) {
> > + if (!(vq->packed.event_flags_shadow & VRING_PACKED_EVENT_FLAG_DISABLE)) {
>
> This seems to be another problem.
>
> Thanks.
>

Here, we are only making this change to maintain consistency with
virtqueue_disable_cb_split.
Is there any concern with doing so?

Thanks.

>
> > vq->packed.event_flags_shadow = VRING_PACKED_EVENT_FLAG_DISABLE;
> > +
> > + /*
> > + * If device triggered an event already it won't trigger one again:
> > + * no need to disable.
> > + */
> > + if (vq->event_triggered)
> > + return;
> > +
> > vq->packed.vring.driver->flags =
> > cpu_to_le16(vq->packed.event_flags_shadow);
> > }
> > @@ -2063,12 +2079,6 @@ void virtqueue_disable_cb(struct virtqueue *_vq)
> > {
> > struct vring_virtqueue *vq = to_vvq(_vq);
> >
> > - /* If device triggered an event already it won't trigger one again:
> > - * no need to disable.
> > - */
> > - if (vq->event_triggered)
> > - return;
> > -
> > if (vq->packed_ring)
> > virtqueue_disable_cb_packed(_vq);
> > else
> > --
> > 2.31.1
> >

2023-03-29 09:54:46

by Xuan Zhuo

[permalink] [raw]
Subject: Re: [External] Re: [PATCH v3] virtio_ring: interrupt disable flag updated to vq even with event_triggered is set

On Wed, 29 Mar 2023 17:33:23 +0800, =?utf-8?b?6buE5p2w?= <[email protected]> wrote:
> Xuan Zhuo <[email protected]> 于2023年3月29日周三 17:27写道:
> >
> > On Wed, 29 Mar 2023 15:28:41 +0800, Albert Huang <[email protected]> wrote:
> > > From: "huangjie.albert" <[email protected]>
> > >
> > > in virtio_net, if we disable the napi_tx, when we triger a tx interrupt,
> > > the vq->event_triggered will be set to true. It will no longer be set to
> > > false. Unless we explicitly call virtqueue_enable_cb_delayed or
> > > virtqueue_enable_cb_prepare.
> > >
> > > If we disable the napi_tx, it will only be called when the tx ring
> > > buffer is relatively small.
> > >
> > > Because event_triggered is true. Therefore, VRING_AVAIL_F_NO_INTERRUPT or
> > > VRING_PACKED_EVENT_FLAG_DISABLE will not be set. So we update
> > > vring_used_event(&vq->split.vring) or vq->packed.vring.driver->off_wrap
> > > every time we call virtqueue_get_buf_ctx.This bring more interruptions.
> > >
> > > To summarize:
> > > 1) event_triggered was set to true in vring_interrupt()
> > > 2) after this nothing will happen for virtqueue_disable_cb() so
> > > VRING_AVAIL_F_NO_INTERRUPT is not set in avail_flags_shadow
> > > 3) virtqueue_get_buf_ctx_split() will still think the cb is enabled
> > > then it tries to publish new event
> > >
> > > To fix:
> > > update VRING_AVAIL_F_NO_INTERRUPT or VRING_PACKED_EVENT_FLAG_DISABLE to vq
> > > when we call virtqueue_disable_cb even the event_triggered is set to true.
> > >
> > > Tested with iperf:
> > > iperf3 tcp stream:
> > > vm1 -----------------> vm2
> > > vm2 just receives tcp data stream from vm1, and sends the ack to vm1,
> > > there are many tx interrupts in vm2.
> > > but without event_triggered there are just a few tx interrupts.
> > >
> > > v2->v3:
> > > -update the interrupt disable flag even with the event_triggered is set,
> > > -instead of checking whether event_triggered is set in
> > > -virtqueue_get_buf_ctx_{packed/split}, will cause the drivers which have
> > > -not called virtqueue_{enable/disable}_cb to miss notifications.
> > >
> > > Fixes: 8d622d21d248 ("virtio: fix up virtio_disable_cb")
> > > Signed-off-by: huangjie.albert <[email protected]>
> > > Signed-off-by: Michael S. Tsirkin <[email protected]>
> > > Signed-off-by: Jason Wang <[email protected]>
> > > ---
> > > drivers/virtio/virtio_ring.c | 24 +++++++++++++++++-------
> > > 1 file changed, 17 insertions(+), 7 deletions(-)
> > >
> > > diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
> > > index 307e139cb11d..ad74463a48ee 100644
> > > --- a/drivers/virtio/virtio_ring.c
> > > +++ b/drivers/virtio/virtio_ring.c
> > > @@ -812,6 +812,14 @@ static void virtqueue_disable_cb_split(struct virtqueue *_vq)
> > >
> > > if (!(vq->split.avail_flags_shadow & VRING_AVAIL_F_NO_INTERRUPT)) {
> > > vq->split.avail_flags_shadow |= VRING_AVAIL_F_NO_INTERRUPT;
> > > +
> > > + /*
> > > + * If device triggered an event already it won't trigger one again:
> > > + * no need to disable.
> > > + */
> > > + if (vq->event_triggered)
> > > + return;
> > > +
> > > if (vq->event)
> > > /* TODO: this is a hack. Figure out a cleaner value to write. */
> > > vring_used_event(&vq->split.vring) = 0x0;
> > > @@ -1544,8 +1552,16 @@ static void virtqueue_disable_cb_packed(struct virtqueue *_vq)
> > > {
> > > struct vring_virtqueue *vq = to_vvq(_vq);
> > >
> > > - if (vq->packed.event_flags_shadow != VRING_PACKED_EVENT_FLAG_DISABLE) {
> > > + if (!(vq->packed.event_flags_shadow & VRING_PACKED_EVENT_FLAG_DISABLE)) {
> >
> > This seems to be another problem.
> >
> > Thanks.
> >
>
> Here, we are only making this change to maintain consistency with
> virtqueue_disable_cb_split.
> Is there any concern with doing so?

I'm not sure why the use_flags_shadow use "!=" to judge, but it seems
that all places are used like this. So we'd better keep the original. If it is
necessary to modify it here, I think a separate commit should be posted.
Even if it is just to keep it consistent with split.


Thanks.



>
> Thanks.
>
> >
> > > vq->packed.event_flags_shadow = VRING_PACKED_EVENT_FLAG_DISABLE;
> > > +
> > > + /*
> > > + * If device triggered an event already it won't trigger one again:
> > > + * no need to disable.
> > > + */
> > > + if (vq->event_triggered)
> > > + return;
> > > +
> > > vq->packed.vring.driver->flags =
> > > cpu_to_le16(vq->packed.event_flags_shadow);
> > > }
> > > @@ -2063,12 +2079,6 @@ void virtqueue_disable_cb(struct virtqueue *_vq)
> > > {
> > > struct vring_virtqueue *vq = to_vvq(_vq);
> > >
> > > - /* If device triggered an event already it won't trigger one again:
> > > - * no need to disable.
> > > - */
> > > - if (vq->event_triggered)
> > > - return;
> > > -
> > > if (vq->packed_ring)
> > > virtqueue_disable_cb_packed(_vq);
> > > else
> > > --
> > > 2.31.1
> > >

2023-03-29 10:22:15

by 黄杰

[permalink] [raw]
Subject: Re: [External] Re: [PATCH v3] virtio_ring: interrupt disable flag updated to vq even with event_triggered is set

Xuan Zhuo <[email protected]> 于2023年3月29日周三 17:53写道:
>
> On Wed, 29 Mar 2023 17:33:23 +0800, =?utf-8?b?6buE5p2w?= <[email protected]> wrote:
> > Xuan Zhuo <[email protected]> 于2023年3月29日周三 17:27写道:
> > >
> > > On Wed, 29 Mar 2023 15:28:41 +0800, Albert Huang <[email protected]> wrote:
> > > > From: "huangjie.albert" <[email protected]>
> > > >
> > > > in virtio_net, if we disable the napi_tx, when we triger a tx interrupt,
> > > > the vq->event_triggered will be set to true. It will no longer be set to
> > > > false. Unless we explicitly call virtqueue_enable_cb_delayed or
> > > > virtqueue_enable_cb_prepare.
> > > >
> > > > If we disable the napi_tx, it will only be called when the tx ring
> > > > buffer is relatively small.
> > > >
> > > > Because event_triggered is true. Therefore, VRING_AVAIL_F_NO_INTERRUPT or
> > > > VRING_PACKED_EVENT_FLAG_DISABLE will not be set. So we update
> > > > vring_used_event(&vq->split.vring) or vq->packed.vring.driver->off_wrap
> > > > every time we call virtqueue_get_buf_ctx.This bring more interruptions.
> > > >
> > > > To summarize:
> > > > 1) event_triggered was set to true in vring_interrupt()
> > > > 2) after this nothing will happen for virtqueue_disable_cb() so
> > > > VRING_AVAIL_F_NO_INTERRUPT is not set in avail_flags_shadow
> > > > 3) virtqueue_get_buf_ctx_split() will still think the cb is enabled
> > > > then it tries to publish new event
> > > >
> > > > To fix:
> > > > update VRING_AVAIL_F_NO_INTERRUPT or VRING_PACKED_EVENT_FLAG_DISABLE to vq
> > > > when we call virtqueue_disable_cb even the event_triggered is set to true.
> > > >
> > > > Tested with iperf:
> > > > iperf3 tcp stream:
> > > > vm1 -----------------> vm2
> > > > vm2 just receives tcp data stream from vm1, and sends the ack to vm1,
> > > > there are many tx interrupts in vm2.
> > > > but without event_triggered there are just a few tx interrupts.
> > > >
> > > > v2->v3:
> > > > -update the interrupt disable flag even with the event_triggered is set,
> > > > -instead of checking whether event_triggered is set in
> > > > -virtqueue_get_buf_ctx_{packed/split}, will cause the drivers which have
> > > > -not called virtqueue_{enable/disable}_cb to miss notifications.
> > > >
> > > > Fixes: 8d622d21d248 ("virtio: fix up virtio_disable_cb")
> > > > Signed-off-by: huangjie.albert <[email protected]>
> > > > Signed-off-by: Michael S. Tsirkin <[email protected]>
> > > > Signed-off-by: Jason Wang <[email protected]>
> > > > ---
> > > > drivers/virtio/virtio_ring.c | 24 +++++++++++++++++-------
> > > > 1 file changed, 17 insertions(+), 7 deletions(-)
> > > >
> > > > diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
> > > > index 307e139cb11d..ad74463a48ee 100644
> > > > --- a/drivers/virtio/virtio_ring.c
> > > > +++ b/drivers/virtio/virtio_ring.c
> > > > @@ -812,6 +812,14 @@ static void virtqueue_disable_cb_split(struct virtqueue *_vq)
> > > >
> > > > if (!(vq->split.avail_flags_shadow & VRING_AVAIL_F_NO_INTERRUPT)) {
> > > > vq->split.avail_flags_shadow |= VRING_AVAIL_F_NO_INTERRUPT;
> > > > +
> > > > + /*
> > > > + * If device triggered an event already it won't trigger one again:
> > > > + * no need to disable.
> > > > + */
> > > > + if (vq->event_triggered)
> > > > + return;
> > > > +
> > > > if (vq->event)
> > > > /* TODO: this is a hack. Figure out a cleaner value to write. */
> > > > vring_used_event(&vq->split.vring) = 0x0;
> > > > @@ -1544,8 +1552,16 @@ static void virtqueue_disable_cb_packed(struct virtqueue *_vq)
> > > > {
> > > > struct vring_virtqueue *vq = to_vvq(_vq);
> > > >
> > > > - if (vq->packed.event_flags_shadow != VRING_PACKED_EVENT_FLAG_DISABLE) {
> > > > + if (!(vq->packed.event_flags_shadow & VRING_PACKED_EVENT_FLAG_DISABLE)) {
> > >
> > > This seems to be another problem.
> > >
> > > Thanks.
> > >
> >
> > Here, we are only making this change to maintain consistency with
> > virtqueue_disable_cb_split.
> > Is there any concern with doing so?
>
> I'm not sure why the use_flags_shadow use "!=" to judge, but it seems
> that all places are used like this. So we'd better keep the original. If it is
> necessary to modify it here, I think a separate commit should be posted.
> Even if it is just to keep it consistent with split.
>

Let's create a separate commit for this change, and I'll modify the
current commit.
However, the original judgment method in this location was problematic

Thanks.

>
> Thanks.
>
>
>
> >
> > Thanks.
> >
> > >
> > > > vq->packed.event_flags_shadow = VRING_PACKED_EVENT_FLAG_DISABLE;
> > > > +
> > > > + /*
> > > > + * If device triggered an event already it won't trigger one again:
> > > > + * no need to disable.
> > > > + */
> > > > + if (vq->event_triggered)
> > > > + return;
> > > > +
> > > > vq->packed.vring.driver->flags =
> > > > cpu_to_le16(vq->packed.event_flags_shadow);
> > > > }
> > > > @@ -2063,12 +2079,6 @@ void virtqueue_disable_cb(struct virtqueue *_vq)
> > > > {
> > > > struct vring_virtqueue *vq = to_vvq(_vq);
> > > >
> > > > - /* If device triggered an event already it won't trigger one again:
> > > > - * no need to disable.
> > > > - */
> > > > - if (vq->event_triggered)
> > > > - return;
> > > > -
> > > > if (vq->packed_ring)
> > > > virtqueue_disable_cb_packed(_vq);
> > > > else
> > > > --
> > > > 2.31.1
> > > >