diff options
author | Martin KaFai Lau <kafai@fb.com> | 2015-09-15 14:30:09 -0700 |
---|---|---|
committer | David S. Miller <davem@davemloft.net> | 2015-09-15 14:53:05 -0700 |
commit | 70da5b5c532f0ec8aa76b4f46158da5f010f34b3 (patch) | |
tree | 11b8e0054461b9788d669215416655f112545670 /net/ipv6/ip6_tunnel.c | |
parent | 8e3d5be7368107f0c27a1f8126d79b01a47e9567 (diff) | |
download | linux-70da5b5c532f0ec8aa76b4f46158da5f010f34b3.tar.bz2 |
ipv6: Replace spinlock with seqlock and rcu in ip6_tunnel
This patch uses a seqlock to ensure consistency between idst->dst and
idst->cookie. It also makes dst freeing from fib tree to undergo a
rcu grace period.
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv6/ip6_tunnel.c')
-rw-r--r-- | net/ipv6/ip6_tunnel.c | 51 |
1 files changed, 27 insertions, 24 deletions
diff --git a/net/ipv6/ip6_tunnel.c b/net/ipv6/ip6_tunnel.c index 851cf6d1eb45..983f0d20f96d 100644 --- a/net/ipv6/ip6_tunnel.c +++ b/net/ipv6/ip6_tunnel.c @@ -126,45 +126,48 @@ static struct net_device_stats *ip6_get_stats(struct net_device *dev) * Locking : hash tables are protected by RCU and RTNL */ -static void __ip6_tnl_per_cpu_dst_set(struct ip6_tnl_dst *idst, - struct dst_entry *dst) +static void ip6_tnl_per_cpu_dst_set(struct ip6_tnl_dst *idst, + struct dst_entry *dst) { - dst_release(idst->dst); + write_seqlock_bh(&idst->lock); + dst_release(rcu_dereference_protected( + idst->dst, + lockdep_is_held(&idst->lock.lock))); if (dst) { dst_hold(dst); idst->cookie = rt6_get_cookie((struct rt6_info *)dst); } else { idst->cookie = 0; } - idst->dst = dst; -} - -static void ip6_tnl_per_cpu_dst_set(struct ip6_tnl_dst *idst, - struct dst_entry *dst) -{ - - spin_lock_bh(&idst->lock); - __ip6_tnl_per_cpu_dst_set(idst, dst); - spin_unlock_bh(&idst->lock); + rcu_assign_pointer(idst->dst, dst); + write_sequnlock_bh(&idst->lock); } struct dst_entry *ip6_tnl_dst_get(struct ip6_tnl *t) { struct ip6_tnl_dst *idst; struct dst_entry *dst; + unsigned int seq; + u32 cookie; idst = raw_cpu_ptr(t->dst_cache); - spin_lock_bh(&idst->lock); - dst = idst->dst; - if (dst) { - if (!dst->obsolete || dst->ops->check(dst, idst->cookie)) { - dst_hold(idst->dst); - } else { - __ip6_tnl_per_cpu_dst_set(idst, NULL); - dst = NULL; - } + + rcu_read_lock(); + do { + seq = read_seqbegin(&idst->lock); + dst = rcu_dereference(idst->dst); + cookie = idst->cookie; + } while (read_seqretry(&idst->lock, seq)); + + if (dst && !atomic_inc_not_zero(&dst->__refcnt)) + dst = NULL; + rcu_read_unlock(); + + if (dst && dst->obsolete && !dst->ops->check(dst, cookie)) { + ip6_tnl_per_cpu_dst_set(idst, NULL); + dst_release(dst); + dst = NULL; } - spin_unlock_bh(&idst->lock); return dst; } EXPORT_SYMBOL_GPL(ip6_tnl_dst_get); @@ -204,7 +207,7 @@ int ip6_tnl_dst_init(struct ip6_tnl *t) return -ENOMEM; for_each_possible_cpu(i) - spin_lock_init(&per_cpu_ptr(t->dst_cache, i)->lock); + seqlock_init(&per_cpu_ptr(t->dst_cache, i)->lock); return 0; } |