diff mbox

[V6] virtio-net: send gratuitous packets when needed

Message ID 20120328054428.34415.75432.stgit@amd-6168-8-1.englab.nay.redhat.com
State Accepted, archived
Delegated to: David Miller
Headers show

Commit Message

Jason Wang March 28, 2012, 5:44 a.m. UTC 
As hypervior does not have the knowledge of guest network configuration, it's
better to ask guest to send gratuitous packets when needed.

Guest tests VIRTIO_NET_S_ANNOUNCE bit during config change interrupt and when it
is set, a workqueue is scheduled to send gratuitous packet through
NETDEV_NOTIFY_PEERS. This feature is negotiated through bit
VIRTIO_NET_F_GUEST_ANNOUNCE.

Changes from v5:
- notify the chain before acking the link annoucement
- ack the link announcement notification through control vq

Changes from v4:
- typos
- handle workqueue unconditionally
- move VIRTIO_NET_S_ANNOUNCE to bit 8 to separate rw bits from ro bits

Changes from v3:
- cancel the workqueue during freeze

Changes from v2:
- fix the race between unregister_dev() and workqueue

Signed-off-by: Jason Wang <jasowang@redhat.com>
---
 drivers/net/virtio_net.c   |   32 +++++++++++++++++++++++++++++++-
 include/linux/virtio_net.h |   13 +++++++++++++
 2 files changed, 44 insertions(+), 1 deletions(-)


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Comments

David Miller April 3, 2012, 9:49 p.m. UTC | #1 
From: Jason Wang <jasowang@redhat.com>
Date: Wed, 28 Mar 2012 13:44:28 +0800

> As hypervior does not have the knowledge of guest network configuration, it's
> better to ask guest to send gratuitous packets when needed.
> 
> Guest tests VIRTIO_NET_S_ANNOUNCE bit during config change interrupt and when it
> is set, a workqueue is scheduled to send gratuitous packet through
> NETDEV_NOTIFY_PEERS. This feature is negotiated through bit
> VIRTIO_NET_F_GUEST_ANNOUNCE.
 ...
> Signed-off-by: Jason Wang <jasowang@redhat.com>

Michael and others, what's the story with this patch?
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Michael S. Tsirkin April 4, 2012, 7:49 a.m. UTC | #2 
On Wed, Mar 28, 2012 at 01:44:28PM +0800, Jason Wang wrote:
> As hypervior does not have the knowledge of guest network configuration, it's
> better to ask guest to send gratuitous packets when needed.
> 
> Guest tests VIRTIO_NET_S_ANNOUNCE bit during config change interrupt and when it
> is set, a workqueue is scheduled to send gratuitous packet through
> NETDEV_NOTIFY_PEERS. This feature is negotiated through bit
> VIRTIO_NET_F_GUEST_ANNOUNCE.
> 
> Changes from v5:
> - notify the chain before acking the link annoucement
> - ack the link announcement notification through control vq
> 
> Changes from v4:
> - typos
> - handle workqueue unconditionally
> - move VIRTIO_NET_S_ANNOUNCE to bit 8 to separate rw bits from ro bits
> 
> Changes from v3:
> - cancel the workqueue during freeze
> 
> Changes from v2:
> - fix the race between unregister_dev() and workqueue
> 
> Signed-off-by: Jason Wang <jasowang@redhat.com>

I think this needs some fixes. See below.
Thanks.

> ---
>  drivers/net/virtio_net.c   |   32 +++++++++++++++++++++++++++++++-
>  include/linux/virtio_net.h |   13 +++++++++++++
>  2 files changed, 44 insertions(+), 1 deletions(-)
> 
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 4880aa8..0f60da7 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -72,6 +72,9 @@ struct virtnet_info {
>  	/* Work struct for refilling if we run low on memory. */
>  	struct delayed_work refill;
>  
> +	/* Work struct for sending gratuitous packets. */

A bit confusing: it does not send anything itself.
A better comment 'for announcing the existence of device
on the network'.

> +	struct work_struct announce;
> +
>  	/* Chain pages by the private ptr. */
>  	struct page *pages;
>  
> @@ -781,12 +784,30 @@ static bool virtnet_send_command(struct virtnet_info *vi, u8 class, u8 cmd,
>  	return status == VIRTIO_NET_OK;
>  }
>  
> +static void virtnet_ack_link_announce(struct virtnet_info *vi)
> +{
> +	if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_ANNOUNCE,
> +				  VIRTIO_NET_CTRL_ANNOUNCE_ACK, NULL,
> +				  0, 0)) {

This can run in parallel with other commands. That's pretty bad -
will corrupt the cvq.
Take rtnl lock around calls to this function?

> +		dev_warn(&vi->dev->dev, "Failed to ack link nnounce.\n");

announce

> +	}

Better to drop {} around a single statement.

> +}
> +
> +static void announce_work(struct work_struct *work)
> +{
> +	struct virtnet_info *vi = container_of(work, struct virtnet_info,
> +					       announce);
> +	netif_notify_peers(vi->dev);
> +	virtnet_ack_link_announce(vi);
> +}
> +
>  static int virtnet_close(struct net_device *dev)
>  {
>  	struct virtnet_info *vi = netdev_priv(dev);
>  
>  	/* Make sure refill_work doesn't re-enable napi! */
>  	cancel_delayed_work_sync(&vi->refill);
> +	cancel_work_sync(&vi->announce);

I think that a config change event can trigger after this point,
so cancel here won't be effective. But why do it here?
virtnet_remove not a better place? We can do it
after remove_vq_common.

>  	napi_disable(&vi->napi);
>  
>  	return 0;
> @@ -962,11 +983,17 @@ static void virtnet_update_status(struct virtnet_info *vi)
>  		return;
>  
>  	/* Ignore unknown (future) status bits */
> -	v &= VIRTIO_NET_S_LINK_UP;
> +	v &= VIRTIO_NET_S_LINK_UP | VIRTIO_NET_S_ANNOUNCE;

The announce bit in vi->status is always clear,
so this is IMO confusing. I would do:

	if (v & VIRTIO_NET_S_ANNOUNCE) {
		schedule
	}

	v &= VIRTIO_NET_S_LINK_UP;

and the rest of the logic is not necessary then.

Also, this might run extra ack announce commands after
VIRTIO_NET_S_ANNOUNCE bit is clear. The spec
isn't clear on whether this is legal.

It would be very hard to fix this, so let's add a comment
stating that it's legal, and clarify the spec
in any case.


>  
>  	if (vi->status == v)
>  		return;
>  
> +	if (v & VIRTIO_NET_S_ANNOUNCE) {
> +		v &= ~VIRTIO_NET_S_ANNOUNCE;
> +		if (v & VIRTIO_NET_S_LINK_UP)
> +			schedule_work(&vi->announce);

I think we really want an nrt wq here - if this triggers
multiple times there's no good reason to try and run
the ack command many times in parallel.

> +	}
> +
>  	vi->status = v;
>  
>  	if (vi->status & VIRTIO_NET_S_LINK_UP) {


> @@ -1076,6 +1103,7 @@ static int virtnet_probe(struct virtio_device *vdev)
>  		goto free;
>  
>  	INIT_DELAYED_WORK(&vi->refill, refill_work);
> +	INIT_WORK(&vi->announce, announce_work);
>  	sg_init_table(vi->rx_sg, ARRAY_SIZE(vi->rx_sg));
>  	sg_init_table(vi->tx_sg, ARRAY_SIZE(vi->tx_sg));
>  
> @@ -1187,6 +1215,7 @@ static int virtnet_freeze(struct virtio_device *vdev)
>  	virtqueue_disable_cb(vi->svq);
>  	if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_VQ))
>  		virtqueue_disable_cb(vi->cvq);
> +	cancel_work_sync(&vi->announce);

A config change event can trigger after this point,
so cancel here won't be effective.
Possibly, we need state like config_enable in the block
device.

Also, what exactly will happen on suspend?
As we reset, ANNOUCE bit will be clear so -
do we forget to announce? Probably not good ...

>  
>  	netif_device_detach(vi->dev);
>  	cancel_delayed_work_sync(&vi->refill);
> @@ -1233,6 +1262,7 @@ static unsigned int features[] = {
>  	VIRTIO_NET_F_GUEST_ECN, VIRTIO_NET_F_GUEST_UFO,
>  	VIRTIO_NET_F_MRG_RXBUF, VIRTIO_NET_F_STATUS, VIRTIO_NET_F_CTRL_VQ,
>  	VIRTIO_NET_F_CTRL_RX, VIRTIO_NET_F_CTRL_VLAN,
> +	VIRTIO_NET_F_GUEST_ANNOUNCE,
>  };
>  
>  static struct virtio_driver virtio_net_driver = {
> diff --git a/include/linux/virtio_net.h b/include/linux/virtio_net.h
> index 970d5a2..383e8a0 100644
> --- a/include/linux/virtio_net.h
> +++ b/include/linux/virtio_net.h
> @@ -49,8 +49,10 @@
>  #define VIRTIO_NET_F_CTRL_RX	18	/* Control channel RX mode support */
>  #define VIRTIO_NET_F_CTRL_VLAN	19	/* Control channel VLAN filtering */
>  #define VIRTIO_NET_F_CTRL_RX_EXTRA 20	/* Extra RX mode control support */
> +#define VIRTIO_NET_F_GUEST_ANNOUNCE 21  /* Guest can send gratituous packet */

Rusty aligned the comments using tabs so let's do it here too?
A better comment 'can announce device on the network'.

>  
>  #define VIRTIO_NET_S_LINK_UP	1	/* Link is up */
> +#define VIRTIO_NET_S_ANNOUNCE   2	/* Announcement is needed */

why 3 spaces before the value here?

>  
>  struct virtio_net_config {
>  	/* The config defining mac address (if VIRTIO_NET_F_MAC) */
> @@ -152,4 +154,15 @@ struct virtio_net_ctrl_mac {
>   #define VIRTIO_NET_CTRL_VLAN_ADD             0
>   #define VIRTIO_NET_CTRL_VLAN_DEL             1
>  
> +/*
> + * Control link announce acknowledgement
> + *
> + * The command VIRTIO_NET_CTRL_ANNOUNCE_ACK is used to indicate that
> + * driver has recevied the notification and device would clear the

s/recevied/received/

A bit clearer to replace 'and' with ; here.

> + * VIRTIO_NET_S_ANNOUNCE bit in the status filed after it received

s/filed/field/
s/received/receives/

> + * this command.
> + */
> +#define VIRTIO_NET_CTRL_ANNOUNCE       3
> + #define VIRTIO_NET_CTRL_ANNOUNCE_ACK         0
> +
>  #endif /* _LINUX_VIRTIO_NET_H */
> 
> _______________________________________________
> Virtualization mailing list
> Virtualization@lists.linux-foundation.org
> https://lists.linuxfoundation.org/mailman/listinfo/virtualization
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Michael S. Tsirkin April 4, 2012, 7:51 a.m. UTC | #3 
On Tue, Apr 03, 2012 at 05:49:05PM -0400, David Miller wrote:
> From: Jason Wang <jasowang@redhat.com>
> Date: Wed, 28 Mar 2012 13:44:28 +0800
> 
> > As hypervior does not have the knowledge of guest network configuration, it's
> > better to ask guest to send gratuitous packets when needed.
> > 
> > Guest tests VIRTIO_NET_S_ANNOUNCE bit during config change interrupt and when it
> > is set, a workqueue is scheduled to send gratuitous packet through
> > NETDEV_NOTIFY_PEERS. This feature is negotiated through bit
> > VIRTIO_NET_F_GUEST_ANNOUNCE.
>  ...
> > Signed-off-by: Jason Wang <jasowang@redhat.com>
> 
> Michael and others, what's the story with this patch?

It's a new feature so it will be 3.5 material when it's ready.
Sent some comments for now.

Thanks,
MST


> _______________________________________________
> Virtualization mailing list
> Virtualization@lists.linux-foundation.org
> https://lists.linuxfoundation.org/mailman/listinfo/virtualization
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Jason Wang April 5, 2012, 5:56 a.m. UTC | #4 
On 04/04/2012 03:49 PM, Michael S. Tsirkin wrote:
> On Wed, Mar 28, 2012 at 01:44:28PM +0800, Jason Wang wrote:
>> As hypervior does not have the knowledge of guest network configuration, it's
>> better to ask guest to send gratuitous packets when needed.
>>
>> Guest tests VIRTIO_NET_S_ANNOUNCE bit during config change interrupt and when it
>> is set, a workqueue is scheduled to send gratuitous packet through
>> NETDEV_NOTIFY_PEERS. This feature is negotiated through bit
>> VIRTIO_NET_F_GUEST_ANNOUNCE.
>>
>> Changes from v5:
>> - notify the chain before acking the link annoucement
>> - ack the link announcement notification through control vq
>>
>> Changes from v4:
>> - typos
>> - handle workqueue unconditionally
>> - move VIRTIO_NET_S_ANNOUNCE to bit 8 to separate rw bits from ro bits
>>
>> Changes from v3:
>> - cancel the workqueue during freeze
>>
>> Changes from v2:
>> - fix the race between unregister_dev() and workqueue
>>
>> Signed-off-by: Jason Wang<jasowang@redhat.com>
> I think this needs some fixes. See below.
> Thanks.
>
>> ---
>>   drivers/net/virtio_net.c   |   32 +++++++++++++++++++++++++++++++-
>>   include/linux/virtio_net.h |   13 +++++++++++++
>>   2 files changed, 44 insertions(+), 1 deletions(-)
>>
>> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
>> index 4880aa8..0f60da7 100644
>> --- a/drivers/net/virtio_net.c
>> +++ b/drivers/net/virtio_net.c
>> @@ -72,6 +72,9 @@ struct virtnet_info {
>>   	/* Work struct for refilling if we run low on memory. */
>>   	struct delayed_work refill;
>>
>> +	/* Work struct for sending gratuitous packets. */
> A bit confusing: it does not send anything itself.
> A better comment 'for announcing the existence of device
> on the network'.
>
>> +	struct work_struct announce;
>> +
>>   	/* Chain pages by the private ptr. */
>>   	struct page *pages;
>>
>> @@ -781,12 +784,30 @@ static bool virtnet_send_command(struct virtnet_info *vi, u8 class, u8 cmd,
>>   	return status == VIRTIO_NET_OK;
>>   }
>>
>> +static void virtnet_ack_link_announce(struct virtnet_info *vi)
>> +{
>> +	if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_ANNOUNCE,
>> +				  VIRTIO_NET_CTRL_ANNOUNCE_ACK, NULL,
>> +				  0, 0)) {
> This can run in parallel with other commands. That's pretty bad -
> will corrupt the cvq.
> Take rtnl lock around calls to this function?

It's only used by callbacks of netif_notify_peers(), so rtnl lock have 
already been hold. Add a comment to clarify this?
>> +		dev_warn(&vi->dev->dev, "Failed to ack link nnounce.\n");
> announce

Sorry for the typos, would double check in the future.
>> +	}
> Better to drop {} around a single statement.
>
>> +}
>> +
>> +static void announce_work(struct work_struct *work)
>> +{
>> +	struct virtnet_info *vi = container_of(work, struct virtnet_info,
>> +					       announce);
>> +	netif_notify_peers(vi->dev);
>> +	virtnet_ack_link_announce(vi);
>> +}
>> +
>>   static int virtnet_close(struct net_device *dev)
>>   {
>>   	struct virtnet_info *vi = netdev_priv(dev);
>>
>>   	/* Make sure refill_work doesn't re-enable napi! */
>>   	cancel_delayed_work_sync(&vi->refill);
>> +	cancel_work_sync(&vi->announce);
> I think that a config change event can trigger after this point,
> so cancel here won't be effective. But why do it here?
> virtnet_remove not a better place? We can do it
> after remove_vq_common.

Sure.
>>   	napi_disable(&vi->napi);
>>
>>   	return 0;
>> @@ -962,11 +983,17 @@ static void virtnet_update_status(struct virtnet_info *vi)
>>   		return;
>>
>>   	/* Ignore unknown (future) status bits */
>> -	v&= VIRTIO_NET_S_LINK_UP;
>> +	v&= VIRTIO_NET_S_LINK_UP | VIRTIO_NET_S_ANNOUNCE;
> The announce bit in vi->status is always clear,
> so this is IMO confusing. I would do:
>
> 	if (v&  VIRTIO_NET_S_ANNOUNCE) {
> 		schedule
> 	}
>
> 	v&= VIRTIO_NET_S_LINK_UP;
>
> and the rest of the logic is not necessary then.
>
> Also, this might run extra ack announce commands after
> VIRTIO_NET_S_ANNOUNCE bit is clear. The spec
> isn't clear on whether this is legal.
>
> It would be very hard to fix this, so let's add a comment
> stating that it's legal, and clarify the spec
> in any case.

How about delay the clearing of VIRTIO_NET_S_ANNOUNCE bit in the 
workqueue and protect the updating with 
spinlock_irqsave()/spinloc_irqrestore()? Then later notification would 
be suppressed if the sending is not completed.
>>
>>   	if (vi->status == v)
>>   		return;
>>
>> +	if (v&  VIRTIO_NET_S_ANNOUNCE) {
>> +		v&= ~VIRTIO_NET_S_ANNOUNCE;
>> +		if (v&  VIRTIO_NET_S_LINK_UP)
>> +			schedule_work(&vi->announce);
> I think we really want an nrt wq here - if this triggers
> multiple times there's no good reason to try and run
> the ack command many times in parallel.

Yes.
>> +	}
>> +
>>   	vi->status = v;
>>
>>   	if (vi->status&  VIRTIO_NET_S_LINK_UP) {
>
>> @@ -1076,6 +1103,7 @@ static int virtnet_probe(struct virtio_device *vdev)
>>   		goto free;
>>
>>   	INIT_DELAYED_WORK(&vi->refill, refill_work);
>> +	INIT_WORK(&vi->announce, announce_work);
>>   	sg_init_table(vi->rx_sg, ARRAY_SIZE(vi->rx_sg));
>>   	sg_init_table(vi->tx_sg, ARRAY_SIZE(vi->tx_sg));
>>
>> @@ -1187,6 +1215,7 @@ static int virtnet_freeze(struct virtio_device *vdev)
>>   	virtqueue_disable_cb(vi->svq);
>>   	if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_VQ))
>>   		virtqueue_disable_cb(vi->cvq);
>> +	cancel_work_sync(&vi->announce);
> A config change event can trigger after this point,
> so cancel here won't be effective.
> Possibly, we need state like config_enable in the block
> device.

Probably needed.
>
> Also, what exactly will happen on suspend?
> As we reset, ANNOUCE bit will be clear so -
> do we forget to announce? Probably not good ...

This problem should be the same as normal suspending/resuming, if user 
want to announce the link they should use arp_notify instead.
>
>>
>>   	netif_device_detach(vi->dev);
>>   	cancel_delayed_work_sync(&vi->refill);
>> @@ -1233,6 +1262,7 @@ static unsigned int features[] = {
>>   	VIRTIO_NET_F_GUEST_ECN, VIRTIO_NET_F_GUEST_UFO,
>>   	VIRTIO_NET_F_MRG_RXBUF, VIRTIO_NET_F_STATUS, VIRTIO_NET_F_CTRL_VQ,
>>   	VIRTIO_NET_F_CTRL_RX, VIRTIO_NET_F_CTRL_VLAN,
>> +	VIRTIO_NET_F_GUEST_ANNOUNCE,
>>   };
>>
>>   static struct virtio_driver virtio_net_driver = {
>> diff --git a/include/linux/virtio_net.h b/include/linux/virtio_net.h
>> index 970d5a2..383e8a0 100644
>> --- a/include/linux/virtio_net.h
>> +++ b/include/linux/virtio_net.h
>> @@ -49,8 +49,10 @@
>>   #define VIRTIO_NET_F_CTRL_RX	18	/* Control channel RX mode support */
>>   #define VIRTIO_NET_F_CTRL_VLAN	19	/* Control channel VLAN filtering */
>>   #define VIRTIO_NET_F_CTRL_RX_EXTRA 20	/* Extra RX mode control support */
>> +#define VIRTIO_NET_F_GUEST_ANNOUNCE 21  /* Guest can send gratituous packet */
> Rusty aligned the comments using tabs so let's do it here too?
> A better comment 'can announce device on the network'.
>
>>
>>   #define VIRTIO_NET_S_LINK_UP	1	/* Link is up */
>> +#define VIRTIO_NET_S_ANNOUNCE   2	/* Announcement is needed */
> why 3 spaces before the value here?
>
>>
>>   struct virtio_net_config {
>>   	/* The config defining mac address (if VIRTIO_NET_F_MAC) */
>> @@ -152,4 +154,15 @@ struct virtio_net_ctrl_mac {
>>    #define VIRTIO_NET_CTRL_VLAN_ADD             0
>>    #define VIRTIO_NET_CTRL_VLAN_DEL             1
>>
>> +/*
>> + * Control link announce acknowledgement
>> + *
>> + * The command VIRTIO_NET_CTRL_ANNOUNCE_ACK is used to indicate that
>> + * driver has recevied the notification and device would clear the
> s/recevied/received/
>
> A bit clearer to replace 'and' with ; here.
>
>> + * VIRTIO_NET_S_ANNOUNCE bit in the status filed after it received
> s/filed/field/
> s/received/receives/
>
>> + * this command.
>> + */
>> +#define VIRTIO_NET_CTRL_ANNOUNCE       3
>> + #define VIRTIO_NET_CTRL_ANNOUNCE_ACK         0
>> +
>>   #endif /* _LINUX_VIRTIO_NET_H */
>>
>> _______________________________________________
>> Virtualization mailing list
>> Virtualization@lists.linux-foundation.org
>> https://lists.linuxfoundation.org/mailman/listinfo/virtualization

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Michael S. Tsirkin April 5, 2012, 6:37 a.m. UTC | #5 
On Thu, Apr 05, 2012 at 01:56:15PM +0800, Jason Wang wrote:
> On 04/04/2012 03:49 PM, Michael S. Tsirkin wrote:
> >On Wed, Mar 28, 2012 at 01:44:28PM +0800, Jason Wang wrote:
> >>As hypervior does not have the knowledge of guest network configuration, it's
> >>better to ask guest to send gratuitous packets when needed.
> >>
> >>Guest tests VIRTIO_NET_S_ANNOUNCE bit during config change interrupt and when it
> >>is set, a workqueue is scheduled to send gratuitous packet through
> >>NETDEV_NOTIFY_PEERS. This feature is negotiated through bit
> >>VIRTIO_NET_F_GUEST_ANNOUNCE.
> >>
> >>Changes from v5:
> >>- notify the chain before acking the link annoucement
> >>- ack the link announcement notification through control vq
> >>
> >>Changes from v4:
> >>- typos
> >>- handle workqueue unconditionally
> >>- move VIRTIO_NET_S_ANNOUNCE to bit 8 to separate rw bits from ro bits
> >>
> >>Changes from v3:
> >>- cancel the workqueue during freeze
> >>
> >>Changes from v2:
> >>- fix the race between unregister_dev() and workqueue
> >>
> >>Signed-off-by: Jason Wang<jasowang@redhat.com>
> >I think this needs some fixes. See below.
> >Thanks.
> >
> >>---
> >>  drivers/net/virtio_net.c   |   32 +++++++++++++++++++++++++++++++-
> >>  include/linux/virtio_net.h |   13 +++++++++++++
> >>  2 files changed, 44 insertions(+), 1 deletions(-)
> >>
> >>diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> >>index 4880aa8..0f60da7 100644
> >>--- a/drivers/net/virtio_net.c
> >>+++ b/drivers/net/virtio_net.c
> >>@@ -72,6 +72,9 @@ struct virtnet_info {
> >>  	/* Work struct for refilling if we run low on memory. */
> >>  	struct delayed_work refill;
> >>
> >>+	/* Work struct for sending gratuitous packets. */
> >A bit confusing: it does not send anything itself.
> >A better comment 'for announcing the existence of device
> >on the network'.
> >
> >>+	struct work_struct announce;
> >>+
> >>  	/* Chain pages by the private ptr. */
> >>  	struct page *pages;
> >>
> >>@@ -781,12 +784,30 @@ static bool virtnet_send_command(struct virtnet_info *vi, u8 class, u8 cmd,
> >>  	return status == VIRTIO_NET_OK;
> >>  }
> >>
> >>+static void virtnet_ack_link_announce(struct virtnet_info *vi)
> >>+{
> >>+	if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_ANNOUNCE,
> >>+				  VIRTIO_NET_CTRL_ANNOUNCE_ACK, NULL,
> >>+				  0, 0)) {
> >This can run in parallel with other commands. That's pretty bad -
> >will corrupt the cvq.
> >Take rtnl lock around calls to this function?
> 
> It's only used by callbacks of netif_notify_peers(), so rtnl lock
> have already been hold. Add a comment to clarify this?
> >>+		dev_warn(&vi->dev->dev, "Failed to ack link nnounce.\n");
> >announce
> 
> Sorry for the typos, would double check in the future.
> >>+	}
> >Better to drop {} around a single statement.
> >
> >>+}
> >>+
> >>+static void announce_work(struct work_struct *work)
> >>+{
> >>+	struct virtnet_info *vi = container_of(work, struct virtnet_info,
> >>+					       announce);
> >>+	netif_notify_peers(vi->dev);
> >>+	virtnet_ack_link_announce(vi);
> >>+}
> >>+
> >>  static int virtnet_close(struct net_device *dev)
> >>  {
> >>  	struct virtnet_info *vi = netdev_priv(dev);
> >>
> >>  	/* Make sure refill_work doesn't re-enable napi! */
> >>  	cancel_delayed_work_sync(&vi->refill);
> >>+	cancel_work_sync(&vi->announce);
> >I think that a config change event can trigger after this point,
> >so cancel here won't be effective. But why do it here?
> >virtnet_remove not a better place? We can do it
> >after remove_vq_common.
> 
> Sure.

Except, trying to send a command on cvq after device
has been reset would deadlock. I suspect we'll need
a flag like block has to prevent this.


> >>  	napi_disable(&vi->napi);
> >>
> >>  	return 0;
> >>@@ -962,11 +983,17 @@ static void virtnet_update_status(struct virtnet_info *vi)
> >>  		return;
> >>
> >>  	/* Ignore unknown (future) status bits */
> >>-	v&= VIRTIO_NET_S_LINK_UP;
> >>+	v&= VIRTIO_NET_S_LINK_UP | VIRTIO_NET_S_ANNOUNCE;
> >The announce bit in vi->status is always clear,
> >so this is IMO confusing. I would do:
> >
> >	if (v&  VIRTIO_NET_S_ANNOUNCE) {
> >		schedule
> >	}
> >
> >	v&= VIRTIO_NET_S_LINK_UP;
> >
> >and the rest of the logic is not necessary then.
> >
> >Also, this might run extra ack announce commands after
> >VIRTIO_NET_S_ANNOUNCE bit is clear. The spec
> >isn't clear on whether this is legal.
> >
> >It would be very hard to fix this, so let's add a comment
> >stating that it's legal, and clarify the spec
> >in any case.
> 
> How about delay the clearing of VIRTIO_NET_S_ANNOUNCE bit in the
> workqueue and protect the updating with
> spinlock_irqsave()/spinloc_irqrestore()? Then later notification
> would be suppressed if the sending is not completed.


Not sure what's meant, just make sure we don't lose
these events.

> >>
> >>  	if (vi->status == v)
> >>  		return;
> >>
> >>+	if (v&  VIRTIO_NET_S_ANNOUNCE) {
> >>+		v&= ~VIRTIO_NET_S_ANNOUNCE;
> >>+		if (v&  VIRTIO_NET_S_LINK_UP)
> >>+			schedule_work(&vi->announce);
> >I think we really want an nrt wq here - if this triggers
> >multiple times there's no good reason to try and run
> >the ack command many times in parallel.
> 
> Yes.
> >>+	}
> >>+
> >>  	vi->status = v;
> >>
> >>  	if (vi->status&  VIRTIO_NET_S_LINK_UP) {
> >
> >>@@ -1076,6 +1103,7 @@ static int virtnet_probe(struct virtio_device *vdev)
> >>  		goto free;
> >>
> >>  	INIT_DELAYED_WORK(&vi->refill, refill_work);
> >>+	INIT_WORK(&vi->announce, announce_work);
> >>  	sg_init_table(vi->rx_sg, ARRAY_SIZE(vi->rx_sg));
> >>  	sg_init_table(vi->tx_sg, ARRAY_SIZE(vi->tx_sg));
> >>
> >>@@ -1187,6 +1215,7 @@ static int virtnet_freeze(struct virtio_device *vdev)
> >>  	virtqueue_disable_cb(vi->svq);
> >>  	if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_VQ))
> >>  		virtqueue_disable_cb(vi->cvq);
> >>+	cancel_work_sync(&vi->announce);
> >A config change event can trigger after this point,
> >so cancel here won't be effective.
> >Possibly, we need state like config_enable in the block
> >device.
> 
> Probably needed.
> >
> >Also, what exactly will happen on suspend?
> >As we reset, ANNOUCE bit will be clear so -
> >do we forget to announce? Probably not good ...
> 
> This problem should be the same as normal suspending/resuming, if
> user want to announce the link they should use arp_notify instead.
> >
> >>
> >>  	netif_device_detach(vi->dev);
> >>  	cancel_delayed_work_sync(&vi->refill);
> >>@@ -1233,6 +1262,7 @@ static unsigned int features[] = {
> >>  	VIRTIO_NET_F_GUEST_ECN, VIRTIO_NET_F_GUEST_UFO,
> >>  	VIRTIO_NET_F_MRG_RXBUF, VIRTIO_NET_F_STATUS, VIRTIO_NET_F_CTRL_VQ,
> >>  	VIRTIO_NET_F_CTRL_RX, VIRTIO_NET_F_CTRL_VLAN,
> >>+	VIRTIO_NET_F_GUEST_ANNOUNCE,
> >>  };
> >>
> >>  static struct virtio_driver virtio_net_driver = {
> >>diff --git a/include/linux/virtio_net.h b/include/linux/virtio_net.h
> >>index 970d5a2..383e8a0 100644
> >>--- a/include/linux/virtio_net.h
> >>+++ b/include/linux/virtio_net.h
> >>@@ -49,8 +49,10 @@
> >>  #define VIRTIO_NET_F_CTRL_RX	18	/* Control channel RX mode support */
> >>  #define VIRTIO_NET_F_CTRL_VLAN	19	/* Control channel VLAN filtering */
> >>  #define VIRTIO_NET_F_CTRL_RX_EXTRA 20	/* Extra RX mode control support */
> >>+#define VIRTIO_NET_F_GUEST_ANNOUNCE 21  /* Guest can send gratituous packet */
> >Rusty aligned the comments using tabs so let's do it here too?
> >A better comment 'can announce device on the network'.
> >
> >>
> >>  #define VIRTIO_NET_S_LINK_UP	1	/* Link is up */
> >>+#define VIRTIO_NET_S_ANNOUNCE   2	/* Announcement is needed */
> >why 3 spaces before the value here?
> >
> >>
> >>  struct virtio_net_config {
> >>  	/* The config defining mac address (if VIRTIO_NET_F_MAC) */
> >>@@ -152,4 +154,15 @@ struct virtio_net_ctrl_mac {
> >>   #define VIRTIO_NET_CTRL_VLAN_ADD             0
> >>   #define VIRTIO_NET_CTRL_VLAN_DEL             1
> >>
> >>+/*
> >>+ * Control link announce acknowledgement
> >>+ *
> >>+ * The command VIRTIO_NET_CTRL_ANNOUNCE_ACK is used to indicate that
> >>+ * driver has recevied the notification and device would clear the
> >s/recevied/received/
> >
> >A bit clearer to replace 'and' with ; here.
> >
> >>+ * VIRTIO_NET_S_ANNOUNCE bit in the status filed after it received
> >s/filed/field/
> >s/received/receives/
> >
> >>+ * this command.
> >>+ */
> >>+#define VIRTIO_NET_CTRL_ANNOUNCE       3
> >>+ #define VIRTIO_NET_CTRL_ANNOUNCE_ACK         0
> >>+
> >>  #endif /* _LINUX_VIRTIO_NET_H */
> >>
> >>_______________________________________________
> >>Virtualization mailing list
> >>Virtualization@lists.linux-foundation.org
> >>https://lists.linuxfoundation.org/mailman/listinfo/virtualization
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diff mbox

Patch

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 4880aa8..0f60da7 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -72,6 +72,9 @@  struct virtnet_info {
 	/* Work struct for refilling if we run low on memory. */
 	struct delayed_work refill;
 
+	/* Work struct for sending gratuitous packets. */
+	struct work_struct announce;
+
 	/* Chain pages by the private ptr. */
 	struct page *pages;
 
@@ -781,12 +784,30 @@  static bool virtnet_send_command(struct virtnet_info *vi, u8 class, u8 cmd,
 	return status == VIRTIO_NET_OK;
 }
 
+static void virtnet_ack_link_announce(struct virtnet_info *vi)
+{
+	if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_ANNOUNCE,
+				  VIRTIO_NET_CTRL_ANNOUNCE_ACK, NULL,
+				  0, 0)) {
+		dev_warn(&vi->dev->dev, "Failed to ack link nnounce.\n");
+	}
+}
+
+static void announce_work(struct work_struct *work)
+{
+	struct virtnet_info *vi = container_of(work, struct virtnet_info,
+					       announce);
+	netif_notify_peers(vi->dev);
+	virtnet_ack_link_announce(vi);
+}
+
 static int virtnet_close(struct net_device *dev)
 {
 	struct virtnet_info *vi = netdev_priv(dev);
 
 	/* Make sure refill_work doesn't re-enable napi! */
 	cancel_delayed_work_sync(&vi->refill);
+	cancel_work_sync(&vi->announce);
 	napi_disable(&vi->napi);
 
 	return 0;
@@ -962,11 +983,17 @@  static void virtnet_update_status(struct virtnet_info *vi)
 		return;
 
 	/* Ignore unknown (future) status bits */
-	v &= VIRTIO_NET_S_LINK_UP;
+	v &= VIRTIO_NET_S_LINK_UP | VIRTIO_NET_S_ANNOUNCE;
 
 	if (vi->status == v)
 		return;
 
+	if (v & VIRTIO_NET_S_ANNOUNCE) {
+		v &= ~VIRTIO_NET_S_ANNOUNCE;
+		if (v & VIRTIO_NET_S_LINK_UP)
+			schedule_work(&vi->announce);
+	}
+
 	vi->status = v;
 
 	if (vi->status & VIRTIO_NET_S_LINK_UP) {
@@ -1076,6 +1103,7 @@  static int virtnet_probe(struct virtio_device *vdev)
 		goto free;
 
 	INIT_DELAYED_WORK(&vi->refill, refill_work);
+	INIT_WORK(&vi->announce, announce_work);
 	sg_init_table(vi->rx_sg, ARRAY_SIZE(vi->rx_sg));
 	sg_init_table(vi->tx_sg, ARRAY_SIZE(vi->tx_sg));
 
@@ -1187,6 +1215,7 @@  static int virtnet_freeze(struct virtio_device *vdev)
 	virtqueue_disable_cb(vi->svq);
 	if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_VQ))
 		virtqueue_disable_cb(vi->cvq);
+	cancel_work_sync(&vi->announce);
 
 	netif_device_detach(vi->dev);
 	cancel_delayed_work_sync(&vi->refill);
@@ -1233,6 +1262,7 @@  static unsigned int features[] = {
 	VIRTIO_NET_F_GUEST_ECN, VIRTIO_NET_F_GUEST_UFO,
 	VIRTIO_NET_F_MRG_RXBUF, VIRTIO_NET_F_STATUS, VIRTIO_NET_F_CTRL_VQ,
 	VIRTIO_NET_F_CTRL_RX, VIRTIO_NET_F_CTRL_VLAN,
+	VIRTIO_NET_F_GUEST_ANNOUNCE,
 };
 
 static struct virtio_driver virtio_net_driver = {
diff --git a/include/linux/virtio_net.h b/include/linux/virtio_net.h
index 970d5a2..383e8a0 100644
--- a/include/linux/virtio_net.h
+++ b/include/linux/virtio_net.h
@@ -49,8 +49,10 @@ 
 #define VIRTIO_NET_F_CTRL_RX	18	/* Control channel RX mode support */
 #define VIRTIO_NET_F_CTRL_VLAN	19	/* Control channel VLAN filtering */
 #define VIRTIO_NET_F_CTRL_RX_EXTRA 20	/* Extra RX mode control support */
+#define VIRTIO_NET_F_GUEST_ANNOUNCE 21  /* Guest can send gratituous packet */
 
 #define VIRTIO_NET_S_LINK_UP	1	/* Link is up */
+#define VIRTIO_NET_S_ANNOUNCE   2	/* Announcement is needed */
 
 struct virtio_net_config {
 	/* The config defining mac address (if VIRTIO_NET_F_MAC) */
@@ -152,4 +154,15 @@  struct virtio_net_ctrl_mac {
  #define VIRTIO_NET_CTRL_VLAN_ADD             0
  #define VIRTIO_NET_CTRL_VLAN_DEL             1
 
+/*
+ * Control link announce acknowledgement
+ *
+ * The command VIRTIO_NET_CTRL_ANNOUNCE_ACK is used to indicate that
+ * driver has recevied the notification and device would clear the
+ * VIRTIO_NET_S_ANNOUNCE bit in the status filed after it received
+ * this command.
+ */
+#define VIRTIO_NET_CTRL_ANNOUNCE       3
+ #define VIRTIO_NET_CTRL_ANNOUNCE_ACK         0
+
 #endif /* _LINUX_VIRTIO_NET_H */