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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: ec7328b591 ("net: bridge: mst: Multiple Spanning Tree (MST) mode")
Reported-by: Ido Schimmel <idosch@nvidia.com>
Closes: https://lore.kernel.org/netdev/20251104120313.1306566-1-razor@blackwall.org/T/#m6888d87658f94ed1725433940f4f4ebb00b5a68b
Signed-off-by: Nikolay Aleksandrov <razor@blackwall.org>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Link: https://patch.msgid.link/20251105111919.1499702-3-razor@blackwall.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
pull/1354/merge
Nikolay Aleksandrov 2025-11-05 13:19:19 +02:00 committed by Jakub Kicinski
parent 8dca36978a
commit ee87c63f9b
3 changed files with 14 additions and 2 deletions
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1
net/bridge/br_if.c
View File

@ -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);

10
net/bridge/br_mst.c
View File

@ -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;

5
net/bridge/br_private.h
View File

@ -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 {