From: Long Li <[email protected]>
When a VF is being exposed form the kernel, it should be marked as "slave"
before exposing to the user-mode. The VF is not usable without netvsc running
as master. The user-mode should never see a VF without the "slave" flag.
This commit moves the code of setting the slave flag to the time before VF is
exposed to user-mode.
Signed-off-by: Long Li <[email protected]>
---
Change since v1:
Use a new function to handle NETDEV_POST_INIT.
drivers/net/hyperv/netvsc_drv.c | 24 +++++++++++++++++-------
1 file changed, 17 insertions(+), 7 deletions(-)
diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c
index ec77fb9dcf89..fdad58dcc6a8 100644
--- a/drivers/net/hyperv/netvsc_drv.c
+++ b/drivers/net/hyperv/netvsc_drv.c
@@ -2206,9 +2206,6 @@ static int netvsc_vf_join(struct net_device *vf_netdev,
goto upper_link_failed;
}
- /* set slave flag before open to prevent IPv6 addrconf */
- vf_netdev->flags |= IFF_SLAVE;
-
schedule_delayed_work(&ndev_ctx->vf_takeover, VF_TAKEOVER_INT);
call_netdevice_notifiers(NETDEV_JOIN, vf_netdev);
@@ -2320,11 +2317,9 @@ static struct net_device *get_netvsc_byslot(const struct net_device *vf_netdev)
*/
list_for_each_entry(ndev_ctx, &netvsc_dev_list, list) {
ndev = hv_get_drvdata(ndev_ctx->device_ctx);
- if (ether_addr_equal(vf_netdev->perm_addr, ndev->perm_addr)) {
- netdev_notice(vf_netdev,
- "falling back to mac addr based matching\n");
+ if (ether_addr_equal(vf_netdev->perm_addr, ndev->perm_addr) ||
+ ether_addr_equal(vf_netdev->dev_addr, ndev->perm_addr))
return ndev;
- }
}
netdev_notice(vf_netdev,
@@ -2332,6 +2327,19 @@ static struct net_device *get_netvsc_byslot(const struct net_device *vf_netdev)
return NULL;
}
+static int netvsc_prepare_slave(struct net_device *vf_netdev)
+{
+ struct net_device *ndev;
+
+ ndev = get_netvsc_byslot(vf_netdev);
+ if (!ndev)
+ return NOTIFY_DONE;
+
+ /* set slave flag before open to prevent IPv6 addrconf */
+ vf_netdev->flags |= IFF_SLAVE;
+ return NOTIFY_DONE;
+}
+
static int netvsc_register_vf(struct net_device *vf_netdev)
{
struct net_device_context *net_device_ctx;
@@ -2753,6 +2761,8 @@ static int netvsc_netdev_event(struct notifier_block *this,
return NOTIFY_DONE;
switch (event) {
+ case NETDEV_POST_INIT:
+ return netvsc_prepare_slave(event_dev);
case NETDEV_REGISTER:
return netvsc_register_vf(event_dev);
case NETDEV_UNREGISTER:
--
2.34.1
On Fri, 27 Oct 2023 13:59:50 -0700 [email protected] wrote:
> When a VF is being exposed form the kernel, it should be marked as "slave"
> before exposing to the user-mode. The VF is not usable without netvsc running
> as master. The user-mode should never see a VF without the "slave" flag.
>
> This commit moves the code of setting the slave flag to the time before VF is
> exposed to user-mode.
Can you give a real example in the commit message of a flow in user
space which would get confused by seeing the VF netdev without
IFF_SLAVE?
You're only moving setting IFF_SLAVE but not linking the master,
is there no code which would assume that if SLAVE is set there
is a master?
> Subject: Re: [Patch v2] hv_netvsc: Mark VF as slave before exposing it to user-
> mode
>
> On Fri, 27 Oct 2023 13:59:50 -0700 [email protected] wrote:
> > When a VF is being exposed form the kernel, it should be marked as "slave"
> > before exposing to the user-mode. The VF is not usable without netvsc
> > running as master. The user-mode should never see a VF without the "slave"
> flag.
> >
> > This commit moves the code of setting the slave flag to the time
> > before VF is exposed to user-mode.
>
> Can you give a real example in the commit message of a flow in user space
> which would get confused by seeing the VF netdev without IFF_SLAVE?
A user-mode program may see the VF netdev show up without SLAVE flag before seeing the NETVSC netdev. It may try to configure the VF before it will be bonded to a NETVSC.
With the IFF_SLAVE correctly set at the time of VF showing up to the user-mode, it can rely on this flag to decide if this device should be ignored. (without implementing some timeout logic to detect a potential NETVSC device that may show up later)
>
> You're only moving setting IFF_SLAVE but not linking the master, is there no
> code which would assume that if SLAVE is set there is a master?
The same (taking IFF_SLAVE without linking to master) is done in the original code before VF is joined, but it was for another purpose. I think there is a gap between when the VF is acted upon by other parts of the system and when it's bonded.