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authorJulian Anastasov <ja@ssi.bg>2013-09-12 11:21:07 +0300
committerSimon Horman <horms@verge.net.au>2013-09-18 14:39:03 -0500
commitbcbde4c0a7556cca72874c5e1efa4dccb5198a2b (patch)
tree73e5f985bbcd5a976c26dd75e4672ac2b70b9270 /net
parentc16526a7b99c1c28e9670a8c8e3dbcf741bb32be (diff)
downloadlinux-linaro-stable-bcbde4c0a7556cca72874c5e1efa4dccb5198a2b.tar.gz
ipvs: make the service replacement more robust
commit 578bc3ef1e473a ("ipvs: reorganize dest trash") added IP_VS_DEST_STATE_REMOVING flag and RCU callback named ip_vs_dest_wait_readers() to keep dests and services after removal for at least a RCU grace period. But we have the following corner cases: - we can not reuse the same dest if its service is removed while IP_VS_DEST_STATE_REMOVING is still set because another dest removal in the first grace period can not extend this period. It can happen when ipvsadm -C && ipvsadm -R is used. - dest->svc can be replaced but ip_vs_in_stats() and ip_vs_out_stats() have no explicit read memory barriers when accessing dest->svc. It can happen that dest->svc was just freed (replaced) while we use it to update the stats. We solve the problems as follows: - IP_VS_DEST_STATE_REMOVING is removed and we ensure a fixed idle period for the dest (IP_VS_DEST_TRASH_PERIOD). idle_start will remember when for first time after deletion we noticed dest->refcnt=0. Later, the connections can grab a reference while in RCU grace period but if refcnt becomes 0 we can safely free the dest and its svc. - dest->svc becomes RCU pointer. As result, we add explicit RCU locking in ip_vs_in_stats() and ip_vs_out_stats(). - __ip_vs_unbind_svc is renamed to __ip_vs_svc_put(), it now can free the service immediately or after a RCU grace period. dest->svc is not set to NULL anymore. As result, unlinked dests and their services are freed always after IP_VS_DEST_TRASH_PERIOD period, unused services are freed after a RCU grace period. Signed-off-by: Julian Anastasov <ja@ssi.bg> Signed-off-by: Simon Horman <horms@verge.net.au>
Diffstat (limited to 'net')
-rw-r--r--net/netfilter/ipvs/ip_vs_core.c12
-rw-r--r--net/netfilter/ipvs/ip_vs_ctl.c86
2 files changed, 45 insertions, 53 deletions
diff --git a/net/netfilter/ipvs/ip_vs_core.c b/net/netfilter/ipvs/ip_vs_core.c
index 4f69e83ff836..74fd00c27210 100644
--- a/net/netfilter/ipvs/ip_vs_core.c
+++ b/net/netfilter/ipvs/ip_vs_core.c
@@ -116,6 +116,7 @@ ip_vs_in_stats(struct ip_vs_conn *cp, struct sk_buff *skb)
if (dest && (dest->flags & IP_VS_DEST_F_AVAILABLE)) {
struct ip_vs_cpu_stats *s;
+ struct ip_vs_service *svc;
s = this_cpu_ptr(dest->stats.cpustats);
s->ustats.inpkts++;
@@ -123,11 +124,14 @@ ip_vs_in_stats(struct ip_vs_conn *cp, struct sk_buff *skb)
s->ustats.inbytes += skb->len;
u64_stats_update_end(&s->syncp);
- s = this_cpu_ptr(dest->svc->stats.cpustats);
+ rcu_read_lock();
+ svc = rcu_dereference(dest->svc);
+ s = this_cpu_ptr(svc->stats.cpustats);
s->ustats.inpkts++;
u64_stats_update_begin(&s->syncp);
s->ustats.inbytes += skb->len;
u64_stats_update_end(&s->syncp);
+ rcu_read_unlock();
s = this_cpu_ptr(ipvs->tot_stats.cpustats);
s->ustats.inpkts++;
@@ -146,6 +150,7 @@ ip_vs_out_stats(struct ip_vs_conn *cp, struct sk_buff *skb)
if (dest && (dest->flags & IP_VS_DEST_F_AVAILABLE)) {
struct ip_vs_cpu_stats *s;
+ struct ip_vs_service *svc;
s = this_cpu_ptr(dest->stats.cpustats);
s->ustats.outpkts++;
@@ -153,11 +158,14 @@ ip_vs_out_stats(struct ip_vs_conn *cp, struct sk_buff *skb)
s->ustats.outbytes += skb->len;
u64_stats_update_end(&s->syncp);
- s = this_cpu_ptr(dest->svc->stats.cpustats);
+ rcu_read_lock();
+ svc = rcu_dereference(dest->svc);
+ s = this_cpu_ptr(svc->stats.cpustats);
s->ustats.outpkts++;
u64_stats_update_begin(&s->syncp);
s->ustats.outbytes += skb->len;
u64_stats_update_end(&s->syncp);
+ rcu_read_unlock();
s = this_cpu_ptr(ipvs->tot_stats.cpustats);
s->ustats.outpkts++;
diff --git a/net/netfilter/ipvs/ip_vs_ctl.c b/net/netfilter/ipvs/ip_vs_ctl.c
index c8148e487386..a3df9bddc4f7 100644
--- a/net/netfilter/ipvs/ip_vs_ctl.c
+++ b/net/netfilter/ipvs/ip_vs_ctl.c
@@ -460,7 +460,7 @@ static inline void
__ip_vs_bind_svc(struct ip_vs_dest *dest, struct ip_vs_service *svc)
{
atomic_inc(&svc->refcnt);
- dest->svc = svc;
+ rcu_assign_pointer(dest->svc, svc);
}
static void ip_vs_service_free(struct ip_vs_service *svc)
@@ -470,18 +470,25 @@ static void ip_vs_service_free(struct ip_vs_service *svc)
kfree(svc);
}
-static void
-__ip_vs_unbind_svc(struct ip_vs_dest *dest)
+static void ip_vs_service_rcu_free(struct rcu_head *head)
{
- struct ip_vs_service *svc = dest->svc;
+ struct ip_vs_service *svc;
+
+ svc = container_of(head, struct ip_vs_service, rcu_head);
+ ip_vs_service_free(svc);
+}
- dest->svc = NULL;
+static void __ip_vs_svc_put(struct ip_vs_service *svc, bool do_delay)
+{
if (atomic_dec_and_test(&svc->refcnt)) {
IP_VS_DBG_BUF(3, "Removing service %u/%s:%u\n",
svc->fwmark,
IP_VS_DBG_ADDR(svc->af, &svc->addr),
ntohs(svc->port));
- ip_vs_service_free(svc);
+ if (do_delay)
+ call_rcu(&svc->rcu_head, ip_vs_service_rcu_free);
+ else
+ ip_vs_service_free(svc);
}
}
@@ -667,11 +674,6 @@ ip_vs_trash_get_dest(struct ip_vs_service *svc, const union nf_inet_addr *daddr,
IP_VS_DBG_ADDR(svc->af, &dest->addr),
ntohs(dest->port),
atomic_read(&dest->refcnt));
- /* We can not reuse dest while in grace period
- * because conns still can use dest->svc
- */
- if (test_bit(IP_VS_DEST_STATE_REMOVING, &dest->state))
- continue;
if (dest->af == svc->af &&
ip_vs_addr_equal(svc->af, &dest->addr, daddr) &&
dest->port == dport &&
@@ -697,8 +699,10 @@ out:
static void ip_vs_dest_free(struct ip_vs_dest *dest)
{
+ struct ip_vs_service *svc = rcu_dereference_protected(dest->svc, 1);
+
__ip_vs_dst_cache_reset(dest);
- __ip_vs_unbind_svc(dest);
+ __ip_vs_svc_put(svc, false);
free_percpu(dest->stats.cpustats);
kfree(dest);
}
@@ -771,6 +775,7 @@ __ip_vs_update_dest(struct ip_vs_service *svc, struct ip_vs_dest *dest,
struct ip_vs_dest_user_kern *udest, int add)
{
struct netns_ipvs *ipvs = net_ipvs(svc->net);
+ struct ip_vs_service *old_svc;
struct ip_vs_scheduler *sched;
int conn_flags;
@@ -792,13 +797,14 @@ __ip_vs_update_dest(struct ip_vs_service *svc, struct ip_vs_dest *dest,
atomic_set(&dest->conn_flags, conn_flags);
/* bind the service */
- if (!dest->svc) {
+ old_svc = rcu_dereference_protected(dest->svc, 1);
+ if (!old_svc) {
__ip_vs_bind_svc(dest, svc);
} else {
- if (dest->svc != svc) {
- __ip_vs_unbind_svc(dest);
+ if (old_svc != svc) {
ip_vs_zero_stats(&dest->stats);
__ip_vs_bind_svc(dest, svc);
+ __ip_vs_svc_put(old_svc, true);
}
}
@@ -998,16 +1004,6 @@ ip_vs_edit_dest(struct ip_vs_service *svc, struct ip_vs_dest_user_kern *udest)
return 0;
}
-static void ip_vs_dest_wait_readers(struct rcu_head *head)
-{
- struct ip_vs_dest *dest = container_of(head, struct ip_vs_dest,
- rcu_head);
-
- /* End of grace period after unlinking */
- clear_bit(IP_VS_DEST_STATE_REMOVING, &dest->state);
-}
-
-
/*
* Delete a destination (must be already unlinked from the service)
*/
@@ -1023,20 +1019,16 @@ static void __ip_vs_del_dest(struct net *net, struct ip_vs_dest *dest,
*/
ip_vs_rs_unhash(dest);
- if (!cleanup) {
- set_bit(IP_VS_DEST_STATE_REMOVING, &dest->state);
- call_rcu(&dest->rcu_head, ip_vs_dest_wait_readers);
- }
-
spin_lock_bh(&ipvs->dest_trash_lock);
IP_VS_DBG_BUF(3, "Moving dest %s:%u into trash, dest->refcnt=%d\n",
IP_VS_DBG_ADDR(dest->af, &dest->addr), ntohs(dest->port),
atomic_read(&dest->refcnt));
if (list_empty(&ipvs->dest_trash) && !cleanup)
mod_timer(&ipvs->dest_trash_timer,
- jiffies + IP_VS_DEST_TRASH_PERIOD);
+ jiffies + (IP_VS_DEST_TRASH_PERIOD >> 1));
/* dest lives in trash without reference */
list_add(&dest->t_list, &ipvs->dest_trash);
+ dest->idle_start = 0;
spin_unlock_bh(&ipvs->dest_trash_lock);
ip_vs_dest_put(dest);
}
@@ -1108,24 +1100,30 @@ static void ip_vs_dest_trash_expire(unsigned long data)
struct net *net = (struct net *) data;
struct netns_ipvs *ipvs = net_ipvs(net);
struct ip_vs_dest *dest, *next;
+ unsigned long now = jiffies;
spin_lock(&ipvs->dest_trash_lock);
list_for_each_entry_safe(dest, next, &ipvs->dest_trash, t_list) {
- /* Skip if dest is in grace period */
- if (test_bit(IP_VS_DEST_STATE_REMOVING, &dest->state))
- continue;
if (atomic_read(&dest->refcnt) > 0)
continue;
+ if (dest->idle_start) {
+ if (time_before(now, dest->idle_start +
+ IP_VS_DEST_TRASH_PERIOD))
+ continue;
+ } else {
+ dest->idle_start = max(1UL, now);
+ continue;
+ }
IP_VS_DBG_BUF(3, "Removing destination %u/%s:%u from trash\n",
dest->vfwmark,
- IP_VS_DBG_ADDR(dest->svc->af, &dest->addr),
+ IP_VS_DBG_ADDR(dest->af, &dest->addr),
ntohs(dest->port));
list_del(&dest->t_list);
ip_vs_dest_free(dest);
}
if (!list_empty(&ipvs->dest_trash))
mod_timer(&ipvs->dest_trash_timer,
- jiffies + IP_VS_DEST_TRASH_PERIOD);
+ jiffies + (IP_VS_DEST_TRASH_PERIOD >> 1));
spin_unlock(&ipvs->dest_trash_lock);
}
@@ -1320,14 +1318,6 @@ out:
return ret;
}
-static void ip_vs_service_rcu_free(struct rcu_head *head)
-{
- struct ip_vs_service *svc;
-
- svc = container_of(head, struct ip_vs_service, rcu_head);
- ip_vs_service_free(svc);
-}
-
/*
* Delete a service from the service list
* - The service must be unlinked, unlocked and not referenced!
@@ -1376,13 +1366,7 @@ static void __ip_vs_del_service(struct ip_vs_service *svc, bool cleanup)
/*
* Free the service if nobody refers to it
*/
- if (atomic_dec_and_test(&svc->refcnt)) {
- IP_VS_DBG_BUF(3, "Removing service %u/%s:%u\n",
- svc->fwmark,
- IP_VS_DBG_ADDR(svc->af, &svc->addr),
- ntohs(svc->port));
- call_rcu(&svc->rcu_head, ip_vs_service_rcu_free);
- }
+ __ip_vs_svc_put(svc, true);
/* decrease the module use count */
ip_vs_use_count_dec();