RE: [PATCH net-next] hyperv: Move state setting for link query
> -Original Message-
> From: Jason Wang [mailto:jasow...@redhat.com]
> Sent: Wednesday, March 5, 2014 12:57 AM
> To: Haiyang Zhang; da...@davemloft.net; net...@vger.kernel.org
> Cc: KY Srinivasan; o...@aepfle.de; linux-kernel@vger.kernel.org; driverdev-
> de...@linuxdriverproject.org
> Subject: Re: [PATCH net-next] hyperv: Move state setting for link query
>
> On 03/05/2014 12:57 AM, Haiyang Zhang wrote:
> >
> >> -Original Message-
> >> From: Jason Wang [mailto:jasow...@redhat.com]
> >> Sent: Monday, March 3, 2014 10:10 PM
> >> To: Haiyang Zhang; da...@davemloft.net; net...@vger.kernel.org
> >> Cc: KY Srinivasan; o...@aepfle.de; linux-kernel@vger.kernel.org;
> >> driverdev- de...@linuxdriverproject.org
> >> Subject: Re: [PATCH net-next] hyperv: Move state setting for link
> >> query
> >>
> >> On 03/04/2014 07:54 AM, Haiyang Zhang wrote:
> >>> It moves the state setting for query into rndis_filter_receive_response().
> >>> All callbacks including query-complete and status-callback are
> >>> synchronized by channel->inbound_lock. This prevents pentential race
> >> between them.
> >>
> >> This still looks racy to me. The problem is workqueue is not
> >> synchronized with those here.
> >>
> >> Consider the following case in netvsc_link_change():
> >>
> >> if (rdev->link_state) {
> >> ... receive interrupt ...
> >> rndis_filter_receice_response() which changes rdev->link_state
> >> ...
> >> netif_carrier_off()
> >> }
> >>
> >> And also it need to schedule a work otherwise the link status is out of
> >> sync.
> > The rndis_filter_query_device_link_status() makes the query and wait
> > for the complete message, including set state, before returning.
> >
> > The rndis_filter_query_device_link_status() is called from
> > rndis_filter_device_add(), which is called from either netvsc_change_mtu()
> or netvsc_probe().
> >
> > The change_mtu() and netvsc_link_change() are synchronized by
> rtnl_lock().
> > In netvsc_probe(), the status query & complete happens before
> > register_netdev(), and the netvsc_linkstatus_callback() schedules the work
> only after netdevice is registered.
> > So, there are no race in either case.
> >
> > The carrier_on/off work will be scheduled when netvsc_open() is
> > called. Then, the status will be updated based on the latest link_state.
> >
> > Thanks,
> > - Haiyang
> >
>
> I see. Then if the link status is changing during mtu changing in guest.
> Looks like we may miss a link status updating?
When changing mtu, rndis_filter_device_add() is called, and host will send a
link
status call back immediately after connect-to-netvsp, no matter the link is
changing
or not. This will schedule a work to update the status.
Thanks,
- Haiyang
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Re: [PATCH net-next] hyperv: Move state setting for link query
On 03/05/2014 12:57 AM, Haiyang Zhang wrote:
>
>> -Original Message-
>> From: Jason Wang [mailto:jasow...@redhat.com]
>> Sent: Monday, March 3, 2014 10:10 PM
>> To: Haiyang Zhang; da...@davemloft.net; net...@vger.kernel.org
>> Cc: KY Srinivasan; o...@aepfle.de; linux-kernel@vger.kernel.org; driverdev-
>> de...@linuxdriverproject.org
>> Subject: Re: [PATCH net-next] hyperv: Move state setting for link query
>>
>> On 03/04/2014 07:54 AM, Haiyang Zhang wrote:
>>> It moves the state setting for query into rndis_filter_receive_response().
>>> All callbacks including query-complete and status-callback are
>>> synchronized by channel->inbound_lock. This prevents pentential race
>> between them.
>>
>> This still looks racy to me. The problem is workqueue is not synchronized
>> with
>> those here.
>>
>> Consider the following case in netvsc_link_change():
>>
>> if (rdev->link_state) {
>> ... receive interrupt ...
>> rndis_filter_receice_response() which changes rdev->link_state
>> ...
>> netif_carrier_off()
>> }
>>
>> And also it need to schedule a work otherwise the link status is out of sync.
> The rndis_filter_query_device_link_status() makes the query and wait for the
> complete message, including set state, before returning.
>
> The rndis_filter_query_device_link_status() is called from
> rndis_filter_device_add(),
> which is called from either netvsc_change_mtu() or netvsc_probe().
>
> The change_mtu() and netvsc_link_change() are synchronized by rtnl_lock().
> In netvsc_probe(), the status query & complete happens before
> register_netdev(), and
> the netvsc_linkstatus_callback() schedules the work only after netdevice is
> registered.
> So, there are no race in either case.
>
> The carrier_on/off work will be scheduled when netvsc_open() is called. Then,
> the status will be updated based on the latest link_state.
>
> Thanks,
> - Haiyang
>
I see. Then if the link status is changing during mtu changing in guest.
Looks like we may miss a link status updating?
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Please read the FAQ at http://www.tux.org/lkml/
RE: [PATCH net-next] hyperv: Move state setting for link query
> -Original Message-
> From: Jason Wang [mailto:jasow...@redhat.com]
> Sent: Monday, March 3, 2014 10:10 PM
> To: Haiyang Zhang; da...@davemloft.net; net...@vger.kernel.org
> Cc: KY Srinivasan; o...@aepfle.de; linux-kernel@vger.kernel.org; driverdev-
> de...@linuxdriverproject.org
> Subject: Re: [PATCH net-next] hyperv: Move state setting for link query
>
> On 03/04/2014 07:54 AM, Haiyang Zhang wrote:
> > It moves the state setting for query into rndis_filter_receive_response().
> > All callbacks including query-complete and status-callback are
> > synchronized by channel->inbound_lock. This prevents pentential race
> between them.
>
> This still looks racy to me. The problem is workqueue is not synchronized with
> those here.
>
> Consider the following case in netvsc_link_change():
>
> if (rdev->link_state) {
> ... receive interrupt ...
> rndis_filter_receice_response() which changes rdev->link_state
> ...
> netif_carrier_off()
> }
>
> And also it need to schedule a work otherwise the link status is out of sync.
I will update this patch to schedule a work by the end of probe function.
Thanks,
- Haiyang
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RE: [PATCH net-next] hyperv: Move state setting for link query
> -Original Message-
> From: Jason Wang [mailto:jasow...@redhat.com]
> Sent: Monday, March 3, 2014 10:10 PM
> To: Haiyang Zhang; da...@davemloft.net; net...@vger.kernel.org
> Cc: KY Srinivasan; o...@aepfle.de; linux-kernel@vger.kernel.org; driverdev-
> de...@linuxdriverproject.org
> Subject: Re: [PATCH net-next] hyperv: Move state setting for link query
>
> On 03/04/2014 07:54 AM, Haiyang Zhang wrote:
> > It moves the state setting for query into rndis_filter_receive_response().
> > All callbacks including query-complete and status-callback are
> > synchronized by channel->inbound_lock. This prevents pentential race
> between them.
>
> This still looks racy to me. The problem is workqueue is not synchronized with
> those here.
>
> Consider the following case in netvsc_link_change():
>
> if (rdev->link_state) {
> ... receive interrupt ...
> rndis_filter_receice_response() which changes rdev->link_state
> ...
> netif_carrier_off()
> }
>
> And also it need to schedule a work otherwise the link status is out of sync.
The rndis_filter_query_device_link_status() makes the query and wait for the
complete message, including set state, before returning.
The rndis_filter_query_device_link_status() is called from
rndis_filter_device_add(),
which is called from either netvsc_change_mtu() or netvsc_probe().
The change_mtu() and netvsc_link_change() are synchronized by rtnl_lock().
In netvsc_probe(), the status query & complete happens before
register_netdev(), and
the netvsc_linkstatus_callback() schedules the work only after netdevice is
registered.
So, there are no race in either case.
The carrier_on/off work will be scheduled when netvsc_open() is called. Then,
the status will be updated based on the latest link_state.
Thanks,
- Haiyang
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH net-next] hyperv: Move state setting for link query
On 03/04/2014 07:54 AM, Haiyang Zhang wrote:
> It moves the state setting for query into rndis_filter_receive_response().
> All callbacks including query-complete and status-callback are synchronized
> by channel->inbound_lock. This prevents pentential race between them.
This still looks racy to me. The problem is workqueue is not
synchronized with those here.
Consider the following case in netvsc_link_change():
if (rdev->link_state) {
... receive interrupt ...
rndis_filter_receice_response() which changes rdev->link_state
...
netif_carrier_off()
}
And also it need to schedule a work otherwise the link status is out of
sync.
> Signed-off-by: Haiyang Zhang
> ---
> drivers/net/hyperv/rndis_filter.c | 21 -
> 1 files changed, 20 insertions(+), 1 deletions(-)
>
> diff --git a/drivers/net/hyperv/rndis_filter.c
> b/drivers/net/hyperv/rndis_filter.c
> index f0cc8ef..6a9f602 100644
> --- a/drivers/net/hyperv/rndis_filter.c
> +++ b/drivers/net/hyperv/rndis_filter.c
> @@ -240,6 +240,22 @@ static int rndis_filter_send_request(struct rndis_device
> *dev,
> return ret;
> }
>
> +static void rndis_set_link_state(struct rndis_device *rdev,
> + struct rndis_request *request)
> +{
> + u32 link_status;
> + struct rndis_query_complete *query_complete;
> +
> + query_complete = &request->response_msg.msg.query_complete;
> +
> + if (query_complete->status == RNDIS_STATUS_SUCCESS &&
> + query_complete->info_buflen == sizeof(u32)) {
> + memcpy(&link_status, (void *)((unsigned long)query_complete +
> +query_complete->info_buf_offset), sizeof(u32));
> + rdev->link_state = link_status != 0;
> + }
> +}
> +
> static void rndis_filter_receive_response(struct rndis_device *dev,
> struct rndis_message *resp)
> {
> @@ -269,6 +285,10 @@ static void rndis_filter_receive_response(struct
> rndis_device *dev,
> sizeof(struct rndis_message) + RNDIS_EXT_LEN) {
> memcpy(&request->response_msg, resp,
> resp->msg_len);
> + if (request->request_msg.ndis_msg_type ==
> + RNDIS_MSG_QUERY && request->request_msg.msg.
> + query_req.oid == RNDIS_OID_GEN_MEDIA_CONNECT_STATUS)
> + rndis_set_link_state(dev, request);
> } else {
> netdev_err(ndev,
> "rndis response buffer overflow "
> @@ -617,7 +637,6 @@ static int rndis_filter_query_device_link_status(struct
> rndis_device *dev)
> ret = rndis_filter_query_device(dev,
> RNDIS_OID_GEN_MEDIA_CONNECT_STATUS,
> &link_status, &size);
> - dev->link_state = (link_status != 0) ? true : false;
>
> return ret;
> }
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[PATCH net-next] hyperv: Move state setting for link query
It moves the state setting for query into rndis_filter_receive_response().
All callbacks including query-complete and status-callback are synchronized
by channel->inbound_lock. This prevents pentential race between them.
Signed-off-by: Haiyang Zhang
---
drivers/net/hyperv/rndis_filter.c | 21 -
1 files changed, 20 insertions(+), 1 deletions(-)
diff --git a/drivers/net/hyperv/rndis_filter.c
b/drivers/net/hyperv/rndis_filter.c
index f0cc8ef..6a9f602 100644
--- a/drivers/net/hyperv/rndis_filter.c
+++ b/drivers/net/hyperv/rndis_filter.c
@@ -240,6 +240,22 @@ static int rndis_filter_send_request(struct rndis_device
*dev,
return ret;
}
+static void rndis_set_link_state(struct rndis_device *rdev,
+struct rndis_request *request)
+{
+ u32 link_status;
+ struct rndis_query_complete *query_complete;
+
+ query_complete = &request->response_msg.msg.query_complete;
+
+ if (query_complete->status == RNDIS_STATUS_SUCCESS &&
+ query_complete->info_buflen == sizeof(u32)) {
+ memcpy(&link_status, (void *)((unsigned long)query_complete +
+ query_complete->info_buf_offset), sizeof(u32));
+ rdev->link_state = link_status != 0;
+ }
+}
+
static void rndis_filter_receive_response(struct rndis_device *dev,
struct rndis_message *resp)
{
@@ -269,6 +285,10 @@ static void rndis_filter_receive_response(struct
rndis_device *dev,
sizeof(struct rndis_message) + RNDIS_EXT_LEN) {
memcpy(&request->response_msg, resp,
resp->msg_len);
+ if (request->request_msg.ndis_msg_type ==
+ RNDIS_MSG_QUERY && request->request_msg.msg.
+ query_req.oid == RNDIS_OID_GEN_MEDIA_CONNECT_STATUS)
+ rndis_set_link_state(dev, request);
} else {
netdev_err(ndev,
"rndis response buffer overflow "
@@ -617,7 +637,6 @@ static int rndis_filter_query_device_link_status(struct
rndis_device *dev)
ret = rndis_filter_query_device(dev,
RNDIS_OID_GEN_MEDIA_CONNECT_STATUS,
&link_status, &size);
- dev->link_state = (link_status != 0) ? true : false;
return ret;
}
--
1.7.4.1
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