diff options
| -rw-r--r-- | net/mpls/af_mpls.c | 36 | ||||
| -rw-r--r-- | net/mpls/internal.h | 8 |
2 files changed, 33 insertions, 11 deletions
diff --git a/net/mpls/af_mpls.c b/net/mpls/af_mpls.c index 06ffafde70da..6bdd2f95b576 100644 --- a/net/mpls/af_mpls.c +++ b/net/mpls/af_mpls.c @@ -189,10 +189,15 @@ static u32 mpls_multipath_hash(struct mpls_route *rt, struct sk_buff *skb) return hash; } +/* number of alive nexthops (rt->rt_nhn_alive) and the flags for + * a next hop (nh->nh_flags) are modified by netdev event handlers. + * Since those fields can change at any moment, use READ_ONCE to + * access both. + */ static struct mpls_nh *mpls_select_multipath(struct mpls_route *rt, struct sk_buff *skb) { - int alive = ACCESS_ONCE(rt->rt_nhn_alive); + unsigned int alive; u32 hash = 0; int nh_index = 0; int n = 0; @@ -203,7 +208,8 @@ static struct mpls_nh *mpls_select_multipath(struct mpls_route *rt, if (rt->rt_nhn == 1) goto out; - if (alive <= 0) + alive = READ_ONCE(rt->rt_nhn_alive); + if (alive == 0) return NULL; hash = mpls_multipath_hash(rt, skb); @@ -211,7 +217,9 @@ static struct mpls_nh *mpls_select_multipath(struct mpls_route *rt, if (alive == rt->rt_nhn) goto out; for_nexthops(rt) { - if (nh->nh_flags & (RTNH_F_DEAD | RTNH_F_LINKDOWN)) + unsigned int nh_flags = READ_ONCE(nh->nh_flags); + + if (nh_flags & (RTNH_F_DEAD | RTNH_F_LINKDOWN)) continue; if (n == nh_index) return nh; @@ -1302,7 +1310,6 @@ static void mpls_ifdown(struct net_device *dev, int event) { struct mpls_route __rcu **platform_label; struct net *net = dev_net(dev); - unsigned int nh_flags = RTNH_F_DEAD | RTNH_F_LINKDOWN; unsigned int alive, deleted; unsigned index; @@ -1316,22 +1323,27 @@ static void mpls_ifdown(struct net_device *dev, int event) alive = 0; deleted = 0; change_nexthops(rt) { + unsigned int nh_flags = nh->nh_flags; + if (rtnl_dereference(nh->nh_dev) != dev) goto next; switch (event) { case NETDEV_DOWN: case NETDEV_UNREGISTER: - nh->nh_flags |= RTNH_F_DEAD; + nh_flags |= RTNH_F_DEAD; /* fall through */ case NETDEV_CHANGE: - nh->nh_flags |= RTNH_F_LINKDOWN; + nh_flags |= RTNH_F_LINKDOWN; break; } if (event == NETDEV_UNREGISTER) RCU_INIT_POINTER(nh->nh_dev, NULL); + + if (nh->nh_flags != nh_flags) + WRITE_ONCE(nh->nh_flags, nh_flags); next: - if (!(nh->nh_flags & nh_flags)) + if (!(nh_flags & (RTNH_F_DEAD | RTNH_F_LINKDOWN))) alive++; if (!rtnl_dereference(nh->nh_dev)) deleted++; @@ -1345,7 +1357,7 @@ next: } } -static void mpls_ifup(struct net_device *dev, unsigned int nh_flags) +static void mpls_ifup(struct net_device *dev, unsigned int flags) { struct mpls_route __rcu **platform_label; struct net *net = dev_net(dev); @@ -1361,20 +1373,22 @@ static void mpls_ifup(struct net_device *dev, unsigned int nh_flags) alive = 0; change_nexthops(rt) { + unsigned int nh_flags = nh->nh_flags; struct net_device *nh_dev = rtnl_dereference(nh->nh_dev); - if (!(nh->nh_flags & nh_flags)) { + if (!(nh_flags & flags)) { alive++; continue; } if (nh_dev != dev) continue; alive++; - nh->nh_flags &= ~nh_flags; + nh_flags &= ~flags; + WRITE_ONCE(nh->nh_flags, flags); } endfor_nexthops(rt); - ACCESS_ONCE(rt->rt_nhn_alive) = alive; + WRITE_ONCE(rt->rt_nhn_alive, alive); } } diff --git a/net/mpls/internal.h b/net/mpls/internal.h index 62928d8fabd1..91419fe63464 100644 --- a/net/mpls/internal.h +++ b/net/mpls/internal.h @@ -83,6 +83,10 @@ enum mpls_payload_type { struct mpls_nh { /* next hop label forwarding entry */ struct net_device __rcu *nh_dev; + + /* nh_flags is accessed under RCU in the packet path; it is + * modified handling netdev events with rtnl lock held + */ unsigned int nh_flags; u32 nh_label[MAX_NEW_LABELS]; u8 nh_labels; @@ -124,6 +128,10 @@ struct mpls_route { /* next hop label forwarding entry */ u8 rt_max_alen; u8 rt_ttl_propagate; unsigned int rt_nhn; + + /* rt_nhn_alive is accessed under RCU in the packet path; it + * is modified handling netdev events with rtnl lock held + */ unsigned int rt_nhn_alive; struct mpls_nh rt_nh[0]; }; |