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Message-ID: <20200624102909.dumxk24at65yjyai@soft-dev3.localdomain>
Date: Wed, 24 Jun 2020 12:29:09 +0200
From: Horatiu Vultur <horatiu.vultur@...rochip.com>
To: Nikolay Aleksandrov <nikolay@...ulusnetworks.com>
CC: <roopa@...ulusnetworks.com>, <davem@...emloft.net>,
<kuba@...nel.org>, <netdev@...r.kernel.org>,
<linux-kernel@...r.kernel.org>, <bridge@...ts.linux-foundation.org>
Subject: Re: [PATCH net-next] bridge: mrp: Extend MRP netlink interface with
IFLA_BRIDGE_MRP_CLEAR
The 06/24/2020 11:19, Nikolay Aleksandrov wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
>
> On 24/06/2020 11:05, Horatiu Vultur wrote:
> > In case the userspace daemon dies, then when is restarted it doesn't
> > know if there are any MRP instances in the kernel. Therefore extend the
> > netlink interface to allow the daemon to clear all MRP instances when is
> > started.
> >
> > Signed-off-by: Horatiu Vultur <horatiu.vultur@...rochip.com>
> > ---
> > include/uapi/linux/if_bridge.h | 8 ++++++++
> > net/bridge/br_mrp.c | 15 +++++++++++++++
> > net/bridge/br_mrp_netlink.c | 26 ++++++++++++++++++++++++++
> > net/bridge/br_private_mrp.h | 1 +
> > 4 files changed, 50 insertions(+)
> >
> > diff --git a/include/uapi/linux/if_bridge.h b/include/uapi/linux/if_bridge.h
> > index caa6914a3e53a..2ae7d0c0d46b8 100644
> > --- a/include/uapi/linux/if_bridge.h
> > +++ b/include/uapi/linux/if_bridge.h
> > @@ -166,6 +166,7 @@ enum {
> > IFLA_BRIDGE_MRP_RING_STATE,
> > IFLA_BRIDGE_MRP_RING_ROLE,
> > IFLA_BRIDGE_MRP_START_TEST,
> > + IFLA_BRIDGE_MRP_CLEAR,
> > __IFLA_BRIDGE_MRP_MAX,
> > };
> >
> > @@ -228,6 +229,13 @@ enum {
> >
> > #define IFLA_BRIDGE_MRP_START_TEST_MAX (__IFLA_BRIDGE_MRP_START_TEST_MAX - 1)
> >
> > +enum {
> > + IFLA_BRIDGE_MRP_CLEAR_UNSPEC,
> > + __IFLA_BRIDGE_MRP_CLEAR_MAX,
> > +};
>
> Out of curiousity - do you plan to have any clean attributes?
> In case you don't this can simply be a flag that clears the MRP instances instead
> of a nested attribute.
Currently I don't plan to add any clean attributes. But I have used the
nested attribute just in case in the future something will be needed.
>
> > +
> > +#define IFLA_BRIDGE_MRP_CLEAR_MAX (__IFLA_BRIDGE_MRP_CLEAR_MAX - 1)
> > +
> > struct br_mrp_instance {
> > __u32 ring_id;
> > __u32 p_ifindex;
> > diff --git a/net/bridge/br_mrp.c b/net/bridge/br_mrp.c
> > index 24986ec7d38cc..02d102edaaaad 100644
> > --- a/net/bridge/br_mrp.c
> > +++ b/net/bridge/br_mrp.c
> > @@ -372,6 +372,21 @@ int br_mrp_del(struct net_bridge *br, struct br_mrp_instance *instance)
> > return 0;
> > }
> >
> > +/* Deletes all MRP instances on the bridge
> > + * note: called under rtnl_lock
> > + */
> > +int br_mrp_clear(struct net_bridge *br)
> > +{
> > + struct br_mrp *mrp;
> > +
> > + list_for_each_entry_rcu(mrp, &br->mrp_list, list,
> > + lockdep_rtnl_is_held()) {
> > + br_mrp_del_impl(br, mrp);
>
> I don't think you're in RCU-protected region here, as the lockdep above confirms, which
> means br_mrp_del_impl() can free mrp and you can access freed memory while walking the list
> (trying to access of the next element).
>
> You should be using list_for_each_entry_safe() to delete elements while walking the list.
Good catch! I will update in the next version.
>
> Cheers,
> Nik
>
> > + }
> > +
> > + return 0;
> > +}
> > +
> > /* Set port state, port state can be forwarding, blocked or disabled
> > * note: already called with rtnl_lock
> > */
> > diff --git a/net/bridge/br_mrp_netlink.c b/net/bridge/br_mrp_netlink.c
> > index 34b3a8776991f..5e743538464f6 100644
> > --- a/net/bridge/br_mrp_netlink.c
> > +++ b/net/bridge/br_mrp_netlink.c
> > @@ -14,6 +14,7 @@ static const struct nla_policy br_mrp_policy[IFLA_BRIDGE_MRP_MAX + 1] = {
> > [IFLA_BRIDGE_MRP_RING_STATE] = { .type = NLA_NESTED },
> > [IFLA_BRIDGE_MRP_RING_ROLE] = { .type = NLA_NESTED },
> > [IFLA_BRIDGE_MRP_START_TEST] = { .type = NLA_NESTED },
> > + [IFLA_BRIDGE_MRP_CLEAR] = { .type = NLA_NESTED },
> > };
> >
> > static const struct nla_policy
> > @@ -235,6 +236,25 @@ static int br_mrp_start_test_parse(struct net_bridge *br, struct nlattr *attr,
> > return br_mrp_start_test(br, &test);
> > }
> >
> > +static const struct nla_policy
> > +br_mrp_clear_policy[IFLA_BRIDGE_MRP_CLEAR_MAX + 1] = {
> > + [IFLA_BRIDGE_MRP_CLEAR_UNSPEC] = { .type = NLA_REJECT },
> > +};
> > +
> > +static int br_mrp_clear_parse(struct net_bridge *br, struct nlattr *attr,
> > + struct netlink_ext_ack *extack)
> > +{
> > + struct nlattr *tb[IFLA_BRIDGE_MRP_START_TEST_MAX + 1];
> > + int err;
> > +
> > + err = nla_parse_nested(tb, IFLA_BRIDGE_MRP_CLEAR_MAX, attr,
> > + br_mrp_clear_policy, extack);
> > + if (err)
> > + return err;
> > +
> > + return br_mrp_clear(br);
> > +}
> > +
> > int br_mrp_parse(struct net_bridge *br, struct net_bridge_port *p,
> > struct nlattr *attr, int cmd, struct netlink_ext_ack *extack)
> > {
> > @@ -301,6 +321,12 @@ int br_mrp_parse(struct net_bridge *br, struct net_bridge_port *p,
> > return err;
> > }
> >
> > + if (tb[IFLA_BRIDGE_MRP_CLEAR]) {
> > + err = br_mrp_clear_parse(br, tb[IFLA_BRIDGE_MRP_CLEAR], extack);
> > + if (err)
> > + return err;
> > + }
> > +
> > return 0;
> > }
> >
> > diff --git a/net/bridge/br_private_mrp.h b/net/bridge/br_private_mrp.h
> > index 33b255e38ffec..25c3b8596c25b 100644
> > --- a/net/bridge/br_private_mrp.h
> > +++ b/net/bridge/br_private_mrp.h
> > @@ -36,6 +36,7 @@ struct br_mrp {
> > /* br_mrp.c */
> > int br_mrp_add(struct net_bridge *br, struct br_mrp_instance *instance);
> > int br_mrp_del(struct net_bridge *br, struct br_mrp_instance *instance);
> > +int br_mrp_clear(struct net_bridge *br);
> > int br_mrp_set_port_state(struct net_bridge_port *p,
> > enum br_mrp_port_state_type state);
> > int br_mrp_set_port_role(struct net_bridge_port *p,
> >
>
--
/Horatiu
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