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rtnetlink: add rtnl_link_state check in rtnl_configure_link 

rtnl_configure_link sets dev->rtnl_link_state to
RTNL_LINK_INITIALIZED and unconditionally calls
__dev_notify_flags to notify user-space of dev flags.

current call sequence for rtnl_configure_link
rtnetlink_newlink
    rtnl_link_ops->newlink
    rtnl_configure_link (unconditionally notifies userspace of
                         default and new dev flags)

If a newlink handler wants to call rtnl_configure_link
early, we will end up with duplicate notifications to
user-space.

This patch fixes rtnl_configure_link to check rtnl_link_state
and call __dev_notify_flags with gchanges = 0 if already
RTNL_LINK_INITIALIZED.

Later in the series, this patch will help the following sequence
where a driver implementing newlink can call rtnl_configure_link
to initialize the link early.

makes the following call sequence work:
rtnetlink_newlink
    rtnl_link_ops->newlink (vxlan) -> rtnl_configure_link (initializes
                                                link and notifies
                                                user-space of default
                                                dev flags)
    rtnl_configure_link (updates dev flags if requested by user ifm
                         and notifies user-space of new dev flags)

Signed-off-by: Roopa Prabhu <roopa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Roopa Prabhu 2018-07-20 13:21:01 -07:00 committed by David S. Miller
parent 6e56830776
commit 5025f7f7d5
1 changed files with 6 additions and 3 deletions
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9
net/core/rtnetlink.c
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@ -2759,9 +2759,12 @@ int rtnl_configure_link(struct net_device *dev, const struct ifinfomsg *ifm)
return err;
}
dev->rtnl_link_state = RTNL_LINK_INITIALIZED;
__dev_notify_flags(dev, old_flags, ~0U);
if (dev->rtnl_link_state == RTNL_LINK_INITIALIZED) {
__dev_notify_flags(dev, old_flags, 0U);
} else {
dev->rtnl_link_state = RTNL_LINK_INITIALIZED;
__dev_notify_flags(dev, old_flags, ~0U);
}
return 0;
}
EXPORT_SYMBOL(rtnl_configure_link);