From 026ace060dfe29275d2188297a62fa37d6c1a02c Mon Sep 17 00:00:00 2001 From: Julian Anastasov Date: Thu, 21 Mar 2013 11:58:06 +0200 Subject: [PATCH] ipvs: optimize dst usage for real server Currently when forwarding requests to real servers we use dst_lock and atomic operations when cloning the dst_cache value. As the dst_cache value does not change most of the time it is better to use RCU and to lock dst_lock only when we need to replace the obsoleted dst. For this to work we keep dst_cache in new structure protected by RCU. For packets to remote real servers we will use noref version of dst_cache, it will be valid while we are in RCU read-side critical section because now dst_release for replaced dsts will be invoked after the grace period. Packets to local real servers that are passed to local stack with NF_ACCEPT need a dst clone. Signed-off-by: Julian Anastasov Signed-off by: Hans Schillstrom Signed-off-by: Simon Horman --- include/net/ip_vs.h | 12 +- net/netfilter/ipvs/ip_vs_core.c | 11 +- net/netfilter/ipvs/ip_vs_ctl.c | 25 +++-- net/netfilter/ipvs/ip_vs_xmit.c | 188 ++++++++++++++++++++++++-------- 4 files changed, 177 insertions(+), 59 deletions(-) diff --git a/include/net/ip_vs.h b/include/net/ip_vs.h index 8ad73a834655..a150ff5d838c 100644 --- a/include/net/ip_vs.h +++ b/include/net/ip_vs.h @@ -724,6 +724,13 @@ struct ip_vs_service { struct ip_vs_pe *pe; }; +/* Information for cached dst */ +struct ip_vs_dest_dst { + struct dst_entry *dst_cache; /* destination cache entry */ + u32 dst_cookie; + union nf_inet_addr dst_saddr; + struct rcu_head rcu_head; +}; /* * The real server destination forwarding entry @@ -752,9 +759,7 @@ struct ip_vs_dest { /* for destination cache */ spinlock_t dst_lock; /* lock of dst_cache */ - struct dst_entry *dst_cache; /* destination cache entry */ - u32 dst_cookie; - union nf_inet_addr dst_saddr; + struct ip_vs_dest_dst __rcu *dest_dst; /* cached dst info */ /* for virtual service */ struct ip_vs_service *svc; /* service it belongs to */ @@ -1427,6 +1432,7 @@ extern int ip_vs_dr_xmit(struct sk_buff *skb, struct ip_vs_conn *cp, extern int ip_vs_icmp_xmit(struct sk_buff *skb, struct ip_vs_conn *cp, struct ip_vs_protocol *pp, int offset, unsigned int hooknum, struct ip_vs_iphdr *iph); +extern void ip_vs_dest_dst_rcu_free(struct rcu_head *head); #ifdef CONFIG_IP_VS_IPV6 extern int ip_vs_bypass_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp, diff --git a/net/netfilter/ipvs/ip_vs_core.c b/net/netfilter/ipvs/ip_vs_core.c index 2aef23ed748b..6ad24e7ef440 100644 --- a/net/netfilter/ipvs/ip_vs_core.c +++ b/net/netfilter/ipvs/ip_vs_core.c @@ -1395,10 +1395,13 @@ ip_vs_in_icmp(struct sk_buff *skb, int *related, unsigned int hooknum) goto ignore_ipip; /* Prefer the resulting PMTU */ if (dest) { - spin_lock(&dest->dst_lock); - if (dest->dst_cache) - mtu = dst_mtu(dest->dst_cache); - spin_unlock(&dest->dst_lock); + struct ip_vs_dest_dst *dest_dst; + + rcu_read_lock(); + dest_dst = rcu_dereference(dest->dest_dst); + if (dest_dst) + mtu = dst_mtu(dest_dst->dst_cache); + rcu_read_unlock(); } if (mtu > 68 + sizeof(struct iphdr)) mtu -= sizeof(struct iphdr); diff --git a/net/netfilter/ipvs/ip_vs_ctl.c b/net/netfilter/ipvs/ip_vs_ctl.c index 5265eaa7b42b..ef48cc55f775 100644 --- a/net/netfilter/ipvs/ip_vs_ctl.c +++ b/net/netfilter/ipvs/ip_vs_ctl.c @@ -641,15 +641,26 @@ struct ip_vs_dest *ip_vs_find_dest(struct net *net, int af, return dest; } -/* Release dst_cache for dest in user context */ +void ip_vs_dest_dst_rcu_free(struct rcu_head *head) +{ + struct ip_vs_dest_dst *dest_dst = container_of(head, + struct ip_vs_dest_dst, + rcu_head); + + dst_release(dest_dst->dst_cache); + kfree(dest_dst); +} + +/* Release dest_dst and dst_cache for dest in user context */ static void __ip_vs_dst_cache_reset(struct ip_vs_dest *dest) { - struct dst_entry *old_dst; + struct ip_vs_dest_dst *old; - old_dst = dest->dst_cache; - dest->dst_cache = NULL; - dst_release(old_dst); - dest->dst_saddr.ip = 0; + old = rcu_dereference_protected(dest->dest_dst, 1); + if (old) { + RCU_INIT_POINTER(dest->dest_dst, NULL); + call_rcu(&old->rcu_head, ip_vs_dest_dst_rcu_free); + } } /* @@ -1513,7 +1524,7 @@ static inline void ip_vs_forget_dev(struct ip_vs_dest *dest, struct net_device *dev) { spin_lock_bh(&dest->dst_lock); - if (dest->dst_cache && dest->dst_cache->dev == dev) { + if (dest->dest_dst && dest->dest_dst->dst_cache->dev == dev) { IP_VS_DBG_BUF(3, "Reset dev:%s dest %s:%u ,dest->refcnt=%d\n", dev->name, IP_VS_DBG_ADDR(dest->af, &dest->addr), diff --git a/net/netfilter/ipvs/ip_vs_xmit.c b/net/netfilter/ipvs/ip_vs_xmit.c index 603eb8a50e19..3db7889edefc 100644 --- a/net/netfilter/ipvs/ip_vs_xmit.c +++ b/net/netfilter/ipvs/ip_vs_xmit.c @@ -17,6 +17,8 @@ * - not all connections have destination server, for example, * connections in backup server when fwmark is used * - bypass connections use daddr from packet + * - we can use dst without ref while sending in RCU section, we use + * ref when returning NF_ACCEPT for NAT-ed packet via loopback * LOCAL_OUT rules: * - skb->dev is NULL, skb->protocol is not set (both are set in POST_ROUTING) * - skb->pkt_type is not set yet @@ -54,34 +56,51 @@ enum { IP_VS_RT_MODE_TUNNEL = 32,/* Tunnel mode */ }; +static inline struct ip_vs_dest_dst *ip_vs_dest_dst_alloc(void) +{ + return kmalloc(sizeof(struct ip_vs_dest_dst), GFP_ATOMIC); +} + +static inline void ip_vs_dest_dst_free(struct ip_vs_dest_dst *dest_dst) +{ + kfree(dest_dst); +} + /* * Destination cache to speed up outgoing route lookup */ static inline void -__ip_vs_dst_set(struct ip_vs_dest *dest, struct dst_entry *dst, u32 dst_cookie) +__ip_vs_dst_set(struct ip_vs_dest *dest, struct ip_vs_dest_dst *dest_dst, + struct dst_entry *dst, u32 dst_cookie) { - struct dst_entry *old_dst; + struct ip_vs_dest_dst *old; + + old = rcu_dereference_protected(dest->dest_dst, + lockdep_is_held(&dest->dst_lock)); + + if (dest_dst) { + dest_dst->dst_cache = dst; + dest_dst->dst_cookie = dst_cookie; + } + rcu_assign_pointer(dest->dest_dst, dest_dst); - old_dst = dest->dst_cache; - dest->dst_cache = dst; - dest->dst_cookie = dst_cookie; - dst_release(old_dst); + if (old) + call_rcu(&old->rcu_head, ip_vs_dest_dst_rcu_free); } -static inline struct dst_entry * +static inline struct ip_vs_dest_dst * __ip_vs_dst_check(struct ip_vs_dest *dest) { - struct dst_entry *dst = dest->dst_cache; + struct ip_vs_dest_dst *dest_dst = rcu_dereference(dest->dest_dst); + struct dst_entry *dst; - if (!dst) + if (!dest_dst) return NULL; - if (dst->obsolete && dst->ops->check(dst, dest->dst_cookie) == NULL) { - dest->dst_cache = NULL; - dst_release(dst); + dst = dest_dst->dst_cache; + if (dst->obsolete && + dst->ops->check(dst, dest_dst->dst_cookie) == NULL) return NULL; - } - dst_hold(dst); - return dst; + return dest_dst; } static inline bool @@ -144,35 +163,48 @@ __ip_vs_get_out_rt(struct sk_buff *skb, struct ip_vs_dest *dest, { struct net *net = dev_net(skb_dst(skb)->dev); struct netns_ipvs *ipvs = net_ipvs(net); + struct ip_vs_dest_dst *dest_dst; struct rtable *rt; /* Route to the other host */ struct rtable *ort; /* Original route */ struct iphdr *iph; __be16 df; int mtu; - int local; + int local, noref = 1; if (dest) { - spin_lock(&dest->dst_lock); - rt = (struct rtable *) __ip_vs_dst_check(dest); - if (!rt) { + dest_dst = __ip_vs_dst_check(dest); + if (likely(dest_dst)) + rt = (struct rtable *) dest_dst->dst_cache; + else { + dest_dst = ip_vs_dest_dst_alloc(); + spin_lock(&dest->dst_lock); + if (!dest_dst) { + __ip_vs_dst_set(dest, NULL, NULL, 0); + spin_unlock(&dest->dst_lock); + goto err_unreach; + } rt = do_output_route4(net, dest->addr.ip, rt_mode, - &dest->dst_saddr.ip); + &dest_dst->dst_saddr.ip); if (!rt) { + __ip_vs_dst_set(dest, NULL, NULL, 0); spin_unlock(&dest->dst_lock); + ip_vs_dest_dst_free(dest_dst); goto err_unreach; } - __ip_vs_dst_set(dest, dst_clone(&rt->dst), 0); + __ip_vs_dst_set(dest, dest_dst, &rt->dst, 0); + spin_unlock(&dest->dst_lock); IP_VS_DBG(10, "new dst %pI4, src %pI4, refcnt=%d\n", - &dest->addr.ip, &dest->dst_saddr.ip, + &dest->addr.ip, &dest_dst->dst_saddr.ip, atomic_read(&rt->dst.__refcnt)); } daddr = dest->addr.ip; if (ret_saddr) - *ret_saddr = dest->dst_saddr.ip; - spin_unlock(&dest->dst_lock); + *ret_saddr = dest_dst->dst_saddr.ip; } else { __be32 saddr = htonl(INADDR_ANY); + noref = 0; + /* For such unconfigured boxes avoid many route lookups * for performance reasons because we do not remember saddr */ @@ -210,7 +242,8 @@ __ip_vs_get_out_rt(struct sk_buff *skb, struct ip_vs_dest *dest, goto err_put; } /* skb to local stack, preserve old route */ - ip_rt_put(rt); + if (!noref) + ip_rt_put(rt); return local; } @@ -240,12 +273,19 @@ __ip_vs_get_out_rt(struct sk_buff *skb, struct ip_vs_dest *dest, } skb_dst_drop(skb); - skb_dst_set(skb, &rt->dst); + if (noref) { + if (!local) + skb_dst_set_noref_force(skb, &rt->dst); + else + skb_dst_set(skb, dst_clone(&rt->dst)); + } else + skb_dst_set(skb, &rt->dst); return local; err_put: - ip_rt_put(rt); + if (!noref) + ip_rt_put(rt); return -1; err_unreach: @@ -303,36 +343,48 @@ __ip_vs_get_out_rt_v6(struct sk_buff *skb, struct ip_vs_dest *dest, struct ip_vs_iphdr *ipvsh, int do_xfrm, int rt_mode) { struct net *net = dev_net(skb_dst(skb)->dev); + struct ip_vs_dest_dst *dest_dst; struct rt6_info *rt; /* Route to the other host */ struct rt6_info *ort; /* Original route */ struct dst_entry *dst; int mtu; - int local; + int local, noref = 1; if (dest) { - spin_lock(&dest->dst_lock); - rt = (struct rt6_info *)__ip_vs_dst_check(dest); - if (!rt) { + dest_dst = __ip_vs_dst_check(dest); + if (likely(dest_dst)) + rt = (struct rt6_info *) dest_dst->dst_cache; + else { u32 cookie; + dest_dst = ip_vs_dest_dst_alloc(); + spin_lock(&dest->dst_lock); + if (!dest_dst) { + __ip_vs_dst_set(dest, NULL, NULL, 0); + spin_unlock(&dest->dst_lock); + goto err_unreach; + } dst = __ip_vs_route_output_v6(net, &dest->addr.in6, - &dest->dst_saddr.in6, + &dest_dst->dst_saddr.in6, do_xfrm); if (!dst) { + __ip_vs_dst_set(dest, NULL, NULL, 0); spin_unlock(&dest->dst_lock); + ip_vs_dest_dst_free(dest_dst); goto err_unreach; } rt = (struct rt6_info *) dst; cookie = rt->rt6i_node ? rt->rt6i_node->fn_sernum : 0; - __ip_vs_dst_set(dest, dst_clone(&rt->dst), cookie); + __ip_vs_dst_set(dest, dest_dst, &rt->dst, cookie); + spin_unlock(&dest->dst_lock); IP_VS_DBG(10, "new dst %pI6, src %pI6, refcnt=%d\n", - &dest->addr.in6, &dest->dst_saddr.in6, + &dest->addr.in6, &dest_dst->dst_saddr.in6, atomic_read(&rt->dst.__refcnt)); } if (ret_saddr) - *ret_saddr = dest->dst_saddr.in6; - spin_unlock(&dest->dst_lock); + *ret_saddr = dest_dst->dst_saddr.in6; } else { + noref = 0; dst = __ip_vs_route_output_v6(net, daddr, ret_saddr, do_xfrm); if (!dst) goto err_unreach; @@ -367,7 +419,8 @@ __ip_vs_get_out_rt_v6(struct sk_buff *skb, struct ip_vs_dest *dest, goto err_put; } /* skb to local stack, preserve old route */ - dst_release(&rt->dst); + if (!noref) + dst_release(&rt->dst); return local; } @@ -399,12 +452,19 @@ __ip_vs_get_out_rt_v6(struct sk_buff *skb, struct ip_vs_dest *dest, } skb_dst_drop(skb); - skb_dst_set(skb, &rt->dst); + if (noref) { + if (!local) + skb_dst_set_noref_force(skb, &rt->dst); + else + skb_dst_set(skb, dst_clone(&rt->dst)); + } else + skb_dst_set(skb, &rt->dst); return local; err_put: - dst_release(&rt->dst); + if (!noref) + dst_release(&rt->dst); return -1; err_unreach: @@ -494,6 +554,7 @@ ip_vs_bypass_xmit(struct sk_buff *skb, struct ip_vs_conn *cp, EnterFunction(10); + rcu_read_lock(); if (__ip_vs_get_out_rt(skb, NULL, iph->daddr, IP_VS_RT_MODE_NON_LOCAL, NULL) < 0) goto tx_error; @@ -504,12 +565,14 @@ ip_vs_bypass_xmit(struct sk_buff *skb, struct ip_vs_conn *cp, skb->local_df = 1; ip_vs_send_or_cont(NFPROTO_IPV4, skb, cp, 0); + rcu_read_unlock(); LeaveFunction(10); return NF_STOLEN; tx_error: kfree_skb(skb); + rcu_read_unlock(); LeaveFunction(10); return NF_STOLEN; } @@ -521,6 +584,7 @@ ip_vs_bypass_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp, { EnterFunction(10); + rcu_read_lock(); if (__ip_vs_get_out_rt_v6(skb, NULL, &ipvsh->daddr.in6, NULL, ipvsh, 0, IP_VS_RT_MODE_NON_LOCAL) < 0) goto tx_error; @@ -529,12 +593,14 @@ ip_vs_bypass_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp, skb->local_df = 1; ip_vs_send_or_cont(NFPROTO_IPV6, skb, cp, 0); + rcu_read_unlock(); LeaveFunction(10); return NF_STOLEN; tx_error: kfree_skb(skb); + rcu_read_unlock(); LeaveFunction(10); return NF_STOLEN; } @@ -553,6 +619,7 @@ ip_vs_nat_xmit(struct sk_buff *skb, struct ip_vs_conn *cp, EnterFunction(10); + rcu_read_lock(); /* check if it is a connection of no-client-port */ if (unlikely(cp->flags & IP_VS_CONN_F_NO_CPORT)) { __be16 _pt, *p; @@ -620,12 +687,14 @@ ip_vs_nat_xmit(struct sk_buff *skb, struct ip_vs_conn *cp, skb->local_df = 1; rc = ip_vs_nat_send_or_cont(NFPROTO_IPV4, skb, cp, local); + rcu_read_unlock(); LeaveFunction(10); return rc; tx_error: kfree_skb(skb); + rcu_read_unlock(); LeaveFunction(10); return NF_STOLEN; } @@ -640,6 +709,7 @@ ip_vs_nat_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp, EnterFunction(10); + rcu_read_lock(); /* check if it is a connection of no-client-port */ if (unlikely(cp->flags & IP_VS_CONN_F_NO_CPORT && !ipvsh->fragoffs)) { __be16 _pt, *p; @@ -707,6 +777,7 @@ ip_vs_nat_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp, skb->local_df = 1; rc = ip_vs_nat_send_or_cont(NFPROTO_IPV6, skb, cp, local); + rcu_read_unlock(); LeaveFunction(10); return rc; @@ -714,6 +785,7 @@ ip_vs_nat_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp, tx_error: LeaveFunction(10); kfree_skb(skb); + rcu_read_unlock(); return NF_STOLEN; } #endif @@ -755,6 +827,7 @@ ip_vs_tunnel_xmit(struct sk_buff *skb, struct ip_vs_conn *cp, EnterFunction(10); + rcu_read_lock(); local = __ip_vs_get_out_rt(skb, cp->dest, cp->daddr.ip, IP_VS_RT_MODE_LOCAL | IP_VS_RT_MODE_NON_LOCAL | @@ -762,8 +835,10 @@ ip_vs_tunnel_xmit(struct sk_buff *skb, struct ip_vs_conn *cp, IP_VS_RT_MODE_TUNNEL, &saddr); if (local < 0) goto tx_error; - if (local) + if (local) { + rcu_read_unlock(); return ip_vs_send_or_cont(NFPROTO_IPV4, skb, cp, 1); + } rt = skb_rtable(skb); tdev = rt->dst.dev; @@ -818,6 +893,7 @@ ip_vs_tunnel_xmit(struct sk_buff *skb, struct ip_vs_conn *cp, ip_local_out(skb); else if (ret == NF_DROP) kfree_skb(skb); + rcu_read_unlock(); LeaveFunction(10); @@ -825,6 +901,7 @@ ip_vs_tunnel_xmit(struct sk_buff *skb, struct ip_vs_conn *cp, tx_error: kfree_skb(skb); + rcu_read_unlock(); LeaveFunction(10); return NF_STOLEN; } @@ -844,6 +921,7 @@ ip_vs_tunnel_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp, EnterFunction(10); + rcu_read_lock(); local = __ip_vs_get_out_rt_v6(skb, cp->dest, &cp->daddr.in6, &saddr, ipvsh, 1, IP_VS_RT_MODE_LOCAL | @@ -851,8 +929,10 @@ ip_vs_tunnel_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp, IP_VS_RT_MODE_TUNNEL); if (local < 0) goto tx_error; - if (local) + if (local) { + rcu_read_unlock(); return ip_vs_send_or_cont(NFPROTO_IPV6, skb, cp, 1); + } rt = (struct rt6_info *) skb_dst(skb); tdev = rt->dst.dev; @@ -901,6 +981,7 @@ ip_vs_tunnel_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp, ip6_local_out(skb); else if (ret == NF_DROP) kfree_skb(skb); + rcu_read_unlock(); LeaveFunction(10); @@ -908,6 +989,7 @@ ip_vs_tunnel_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp, tx_error: kfree_skb(skb); + rcu_read_unlock(); LeaveFunction(10); return NF_STOLEN; } @@ -926,14 +1008,17 @@ ip_vs_dr_xmit(struct sk_buff *skb, struct ip_vs_conn *cp, EnterFunction(10); + rcu_read_lock(); local = __ip_vs_get_out_rt(skb, cp->dest, cp->daddr.ip, IP_VS_RT_MODE_LOCAL | IP_VS_RT_MODE_NON_LOCAL | IP_VS_RT_MODE_KNOWN_NH, NULL); if (local < 0) goto tx_error; - if (local) + if (local) { + rcu_read_unlock(); return ip_vs_send_or_cont(NFPROTO_IPV4, skb, cp, 1); + } ip_send_check(ip_hdr(skb)); @@ -941,12 +1026,14 @@ ip_vs_dr_xmit(struct sk_buff *skb, struct ip_vs_conn *cp, skb->local_df = 1; ip_vs_send_or_cont(NFPROTO_IPV4, skb, cp, 0); + rcu_read_unlock(); LeaveFunction(10); return NF_STOLEN; tx_error: kfree_skb(skb); + rcu_read_unlock(); LeaveFunction(10); return NF_STOLEN; } @@ -960,25 +1047,30 @@ ip_vs_dr_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp, EnterFunction(10); + rcu_read_lock(); local = __ip_vs_get_out_rt_v6(skb, cp->dest, &cp->daddr.in6, NULL, ipvsh, 0, IP_VS_RT_MODE_LOCAL | IP_VS_RT_MODE_NON_LOCAL); if (local < 0) goto tx_error; - if (local) + if (local) { + rcu_read_unlock(); return ip_vs_send_or_cont(NFPROTO_IPV6, skb, cp, 1); + } /* Another hack: avoid icmp_send in ip_fragment */ skb->local_df = 1; ip_vs_send_or_cont(NFPROTO_IPV6, skb, cp, 0); + rcu_read_unlock(); LeaveFunction(10); return NF_STOLEN; tx_error: kfree_skb(skb); + rcu_read_unlock(); LeaveFunction(10); return NF_STOLEN; } @@ -1023,6 +1115,7 @@ ip_vs_icmp_xmit(struct sk_buff *skb, struct ip_vs_conn *cp, rt_mode = (hooknum != NF_INET_FORWARD) ? IP_VS_RT_MODE_LOCAL | IP_VS_RT_MODE_NON_LOCAL | IP_VS_RT_MODE_RDR : IP_VS_RT_MODE_NON_LOCAL; + rcu_read_lock(); local = __ip_vs_get_out_rt(skb, cp->dest, cp->daddr.ip, rt_mode, NULL); if (local < 0) goto tx_error; @@ -1067,10 +1160,12 @@ ip_vs_icmp_xmit(struct sk_buff *skb, struct ip_vs_conn *cp, skb->local_df = 1; rc = ip_vs_nat_send_or_cont(NFPROTO_IPV4, skb, cp, local); + rcu_read_unlock(); goto out; tx_error: - dev_kfree_skb(skb); + kfree_skb(skb); + rcu_read_unlock(); rc = NF_STOLEN; out: LeaveFunction(10); @@ -1111,6 +1206,7 @@ ip_vs_icmp_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp, rt_mode = (hooknum != NF_INET_FORWARD) ? IP_VS_RT_MODE_LOCAL | IP_VS_RT_MODE_NON_LOCAL | IP_VS_RT_MODE_RDR : IP_VS_RT_MODE_NON_LOCAL; + rcu_read_lock(); local = __ip_vs_get_out_rt_v6(skb, cp->dest, &cp->daddr.in6, NULL, ipvsh, 0, rt_mode); if (local < 0) @@ -1156,10 +1252,12 @@ ip_vs_icmp_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp, skb->local_df = 1; rc = ip_vs_nat_send_or_cont(NFPROTO_IPV6, skb, cp, local); + rcu_read_unlock(); goto out; tx_error: - dev_kfree_skb(skb); + kfree_skb(skb); + rcu_read_unlock(); rc = NF_STOLEN; out: LeaveFunction(10); -- 2.20.1