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Date: Tue, 03 Mar 2015 08:08:51 -0800
From: roopa <roopa@...ulusnetworks.com>
To: Johannes Berg <johannes@...solutions.net>
CC: netdev@...r.kernel.org,
Stephen Hemminger <stephen@...workplumber.org>,
Johannes Berg <johannes.berg@...el.com>
Subject: Re: [PATCH v4] bridge: fix bridge netlink RCU usage
On 3/3/15, 7:02 AM, Johannes Berg wrote:
> From: Johannes Berg <johannes.berg@...el.com>
>
> When the STP timer fires, it can call br_ifinfo_notify(),
> which in turn ends up in the new br_get_link_af_size().
> This function is annotated to be using RTNL locking, which
> clearly isn't the case here, and thus lockdep warns:
>
> ===============================
> [ INFO: suspicious RCU usage. ]
> 3.19.0+ #569 Not tainted
> -------------------------------
> net/bridge/br_private.h:204 suspicious rcu_dereference_protected() usage!
>
> Fix this by doing RCU locking here.
>
> Fixes: b7853d73e39b ("bridge: add vlan info to bridge setlink and dellink notification messages")
> Signed-off-by: Johannes Berg <johannes.berg@...el.com>
> ---
> net/bridge/br_netlink.c | 14 ++++++++------
> 1 file changed, 8 insertions(+), 6 deletions(-)
>
> diff --git a/net/bridge/br_netlink.c b/net/bridge/br_netlink.c
> index 3de0eefe2b82..c72083968768 100644
> --- a/net/bridge/br_netlink.c
> +++ b/net/bridge/br_netlink.c
> @@ -81,17 +81,19 @@ static size_t br_get_link_af_size_filtered(const struct net_device *dev,
> struct net_port_vlans *pv;
> int num_vlan_infos;
>
> + rcu_read_lock();
> if (br_port_exists(dev))
> - pv = nbp_get_vlan_info(br_port_get_rtnl(dev));
> + pv = nbp_get_vlan_info(br_port_get_rcu(dev));
> else if (dev->priv_flags & IFF_EBRIDGE)
> pv = br_get_vlan_info((struct net_bridge *)netdev_priv(dev));
> else
> - return 0;
> -
> - if (!pv)
> - return 0;
> + pv = NULL;
> + if (pv)
> + num_vlan_infos = br_get_num_vlan_infos(pv, filter_mask);
> + else
> + num_vlan_infos = 0;
> + rcu_read_unlock();
>
> - num_vlan_infos = br_get_num_vlan_infos(pv, filter_mask);
> if (!num_vlan_infos)
> return 0;
>
Acked-by: Roopa Prabhu <roopa@...ulusnetworks.com>
The patch may have to be marked with prefix 'net-next' ?. (unless dave
infers it from the thread)
Thanks again!
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