Commit ee87c63f authored by Nikolay Aleksandrov's avatar Nikolay Aleksandrov Committed by Jakub Kicinski
Browse files

net: bridge: fix MST static key usage 



As Ido pointed out, the static key usage in MST is buggy and should use
inc/dec instead of enable/disable because we can have multiple bridges
with MST enabled which means a single bridge can disable MST for all.
Use static_branch_inc/dec to avoid that. When destroying a bridge decrement
the key if MST was enabled.

Fixes: ec7328b5 ("net: bridge: mst: Multiple Spanning Tree (MST) mode")
Reported-by: default avatarIdo Schimmel <idosch@nvidia.com>
Closes: https://lore.kernel.org/netdev/20251104120313.1306566-1-razor@blackwall.org/T/#m6888d87658f94ed1725433940f4f4ebb00b5a68b


Signed-off-by: default avatarNikolay Aleksandrov <razor@blackwall.org>
Reviewed-by: default avatarIdo Schimmel <idosch@nvidia.com>
Link: https://patch.msgid.link/20251105111919.1499702-3-razor@blackwall.org


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 8dca3697

net/bridge/br_if.c

+1 −0
Original line number Diff line number Diff line
@@ -386,6 +386,7 @@ void br_dev_delete(struct net_device *dev, struct list_head *head) 
		del_nbp(p);

	}



	br_mst_uninit(br);

	br_recalculate_neigh_suppress_enabled(br);



	br_fdb_delete_by_port(br, NULL, 0, 1);

net/bridge/br_mst.c

+8 −2
Original line number Diff line number Diff line
@@ -22,6 +22,12 @@ bool br_mst_enabled(const struct net_device *dev) 
}

EXPORT_SYMBOL_GPL(br_mst_enabled);



void br_mst_uninit(struct net_bridge *br)

{

	if (br_opt_get(br, BROPT_MST_ENABLED))

		static_branch_dec(&br_mst_used);

}



int br_mst_get_info(const struct net_device *dev, u16 msti, unsigned long *vids)

{

	const struct net_bridge_vlan_group *vg;
@@ -225,9 +231,9 @@ int br_mst_set_enabled(struct net_bridge *br, bool on, 
		return err;



	if (on)

		static_branch_enable(&br_mst_used);

		static_branch_inc(&br_mst_used);

	else

		static_branch_disable(&br_mst_used);

		static_branch_dec(&br_mst_used);



	br_opt_toggle(br, BROPT_MST_ENABLED, on);

	return 0;

net/bridge/br_private.h

+5 −0
Original line number Diff line number Diff line
@@ -1954,6 +1954,7 @@ int br_mst_fill_info(struct sk_buff *skb, 
		     const struct net_bridge_vlan_group *vg);

int br_mst_process(struct net_bridge_port *p, const struct nlattr *mst_attr,

		   struct netlink_ext_ack *extack);

void br_mst_uninit(struct net_bridge *br);

#else

static inline bool br_mst_is_enabled(const struct net_bridge_port *p)

{
@@ -1989,6 +1990,10 @@ static inline int br_mst_process(struct net_bridge_port *p, 
{

	return -EOPNOTSUPP;

}



static inline void br_mst_uninit(struct net_bridge *br)

{

}

#endif



struct nf_br_ops {