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Message-Id: <1363945614-11752-6-git-send-email-ja@ssi.bg>
Date: Fri, 22 Mar 2013 11:46:40 +0200
From: Julian Anastasov <ja@....bg>
To: Simon Horman <horms@...ge.net.au>
Cc: lvs-devel@...r.kernel.org, netdev@...r.kernel.org
Subject: [PATCH net-next 05/19] ipvs: convert lblc scheduler to rcu
The schedule method now needs _rcu list-traversal
primitive for svc->destinations. The read_lock for sched_lock is
removed. Use a dead flag to prevent new entries to be created
while scheduler is reclaimed. Use hlist for the hash table.
Signed-off-by: Julian Anastasov <ja@....bg>
---
net/netfilter/ipvs/ip_vs_lblc.c | 96 ++++++++++++++++++++++-----------------
1 files changed, 55 insertions(+), 41 deletions(-)
diff --git a/net/netfilter/ipvs/ip_vs_lblc.c b/net/netfilter/ipvs/ip_vs_lblc.c
index fdd89b9..b873e17 100644
--- a/net/netfilter/ipvs/ip_vs_lblc.c
+++ b/net/netfilter/ipvs/ip_vs_lblc.c
@@ -90,11 +90,12 @@
* IP address and its destination server
*/
struct ip_vs_lblc_entry {
- struct list_head list;
+ struct hlist_node list;
int af; /* address family */
union nf_inet_addr addr; /* destination IP address */
- struct ip_vs_dest *dest; /* real server (cache) */
+ struct ip_vs_dest __rcu *dest; /* real server (cache) */
unsigned long lastuse; /* last used time */
+ struct rcu_head rcu_head;
};
@@ -102,12 +103,14 @@ struct ip_vs_lblc_entry {
* IPVS lblc hash table
*/
struct ip_vs_lblc_table {
- struct list_head bucket[IP_VS_LBLC_TAB_SIZE]; /* hash bucket */
+ struct rcu_head rcu_head;
+ struct hlist_head __rcu bucket[IP_VS_LBLC_TAB_SIZE]; /* hash bucket */
+ struct timer_list periodic_timer; /* collect stale entries */
atomic_t entries; /* number of entries */
int max_size; /* maximum size of entries */
- struct timer_list periodic_timer; /* collect stale entries */
int rover; /* rover for expire check */
int counter; /* counter for no expire */
+ bool dead;
};
@@ -129,13 +132,16 @@ static ctl_table vs_vars_table[] = {
static inline void ip_vs_lblc_free(struct ip_vs_lblc_entry *en)
{
- list_del(&en->list);
+ struct ip_vs_dest *dest;
+
+ hlist_del_rcu(&en->list);
/*
* We don't kfree dest because it is referred either by its service
* or the trash dest list.
*/
- atomic_dec(&en->dest->refcnt);
- kfree(en);
+ dest = rcu_dereference_protected(en->dest, 1);
+ ip_vs_dest_put(dest);
+ kfree_rcu(en, rcu_head);
}
@@ -165,15 +171,12 @@ ip_vs_lblc_hash(struct ip_vs_lblc_table *tbl, struct ip_vs_lblc_entry *en)
{
unsigned int hash = ip_vs_lblc_hashkey(en->af, &en->addr);
- list_add(&en->list, &tbl->bucket[hash]);
+ hlist_add_head_rcu(&en->list, &tbl->bucket[hash]);
atomic_inc(&tbl->entries);
}
-/*
- * Get ip_vs_lblc_entry associated with supplied parameters. Called under read
- * lock
- */
+/* Get ip_vs_lblc_entry associated with supplied parameters. */
static inline struct ip_vs_lblc_entry *
ip_vs_lblc_get(int af, struct ip_vs_lblc_table *tbl,
const union nf_inet_addr *addr)
@@ -181,7 +184,7 @@ ip_vs_lblc_get(int af, struct ip_vs_lblc_table *tbl,
unsigned int hash = ip_vs_lblc_hashkey(af, addr);
struct ip_vs_lblc_entry *en;
- list_for_each_entry(en, &tbl->bucket[hash], list)
+ hlist_for_each_entry_rcu(en, &tbl->bucket[hash], list)
if (ip_vs_addr_equal(af, &en->addr, addr))
return en;
@@ -209,14 +212,20 @@ ip_vs_lblc_new(struct ip_vs_lblc_table *tbl, const union nf_inet_addr *daddr,
ip_vs_addr_copy(dest->af, &en->addr, daddr);
en->lastuse = jiffies;
- atomic_inc(&dest->refcnt);
- en->dest = dest;
+ ip_vs_dest_hold(dest);
+ RCU_INIT_POINTER(en->dest, dest);
ip_vs_lblc_hash(tbl, en);
- } else if (en->dest != dest) {
- atomic_dec(&en->dest->refcnt);
- atomic_inc(&dest->refcnt);
- en->dest = dest;
+ } else {
+ struct ip_vs_dest *old_dest;
+
+ old_dest = rcu_dereference_protected(en->dest, 1);
+ if (old_dest != dest) {
+ ip_vs_dest_put(old_dest);
+ ip_vs_dest_hold(dest);
+ /* No ordering constraints for refcnt */
+ RCU_INIT_POINTER(en->dest, dest);
+ }
}
return en;
@@ -226,17 +235,22 @@ ip_vs_lblc_new(struct ip_vs_lblc_table *tbl, const union nf_inet_addr *daddr,
/*
* Flush all the entries of the specified table.
*/
-static void ip_vs_lblc_flush(struct ip_vs_lblc_table *tbl)
+static void ip_vs_lblc_flush(struct ip_vs_service *svc)
{
- struct ip_vs_lblc_entry *en, *nxt;
+ struct ip_vs_lblc_table *tbl = svc->sched_data;
+ struct ip_vs_lblc_entry *en;
+ struct hlist_node *next;
int i;
+ write_lock_bh(&svc->sched_lock);
+ tbl->dead = 1;
for (i=0; i<IP_VS_LBLC_TAB_SIZE; i++) {
- list_for_each_entry_safe(en, nxt, &tbl->bucket[i], list) {
+ hlist_for_each_entry_safe(en, next, &tbl->bucket[i], list) {
ip_vs_lblc_free(en);
atomic_dec(&tbl->entries);
}
}
+ write_unlock_bh(&svc->sched_lock);
}
static int sysctl_lblc_expiration(struct ip_vs_service *svc)
@@ -252,7 +266,8 @@ static int sysctl_lblc_expiration(struct ip_vs_service *svc)
static inline void ip_vs_lblc_full_check(struct ip_vs_service *svc)
{
struct ip_vs_lblc_table *tbl = svc->sched_data;
- struct ip_vs_lblc_entry *en, *nxt;
+ struct ip_vs_lblc_entry *en;
+ struct hlist_node *next;
unsigned long now = jiffies;
int i, j;
@@ -260,7 +275,7 @@ static inline void ip_vs_lblc_full_check(struct ip_vs_service *svc)
j = (j + 1) & IP_VS_LBLC_TAB_MASK;
write_lock(&svc->sched_lock);
- list_for_each_entry_safe(en, nxt, &tbl->bucket[j], list) {
+ hlist_for_each_entry_safe(en, next, &tbl->bucket[j], list) {
if (time_before(now,
en->lastuse +
sysctl_lblc_expiration(svc)))
@@ -293,7 +308,8 @@ static void ip_vs_lblc_check_expire(unsigned long data)
unsigned long now = jiffies;
int goal;
int i, j;
- struct ip_vs_lblc_entry *en, *nxt;
+ struct ip_vs_lblc_entry *en;
+ struct hlist_node *next;
if ((tbl->counter % COUNT_FOR_FULL_EXPIRATION) == 0) {
/* do full expiration check */
@@ -315,7 +331,7 @@ static void ip_vs_lblc_check_expire(unsigned long data)
j = (j + 1) & IP_VS_LBLC_TAB_MASK;
write_lock(&svc->sched_lock);
- list_for_each_entry_safe(en, nxt, &tbl->bucket[j], list) {
+ hlist_for_each_entry_safe(en, next, &tbl->bucket[j], list) {
if (time_before(now, en->lastuse + ENTRY_TIMEOUT))
continue;
@@ -354,11 +370,12 @@ static int ip_vs_lblc_init_svc(struct ip_vs_service *svc)
* Initialize the hash buckets
*/
for (i=0; i<IP_VS_LBLC_TAB_SIZE; i++) {
- INIT_LIST_HEAD(&tbl->bucket[i]);
+ INIT_HLIST_HEAD(&tbl->bucket[i]);
}
tbl->max_size = IP_VS_LBLC_TAB_SIZE*16;
tbl->rover = 0;
tbl->counter = 1;
+ tbl->dead = 0;
/*
* Hook periodic timer for garbage collection
@@ -379,10 +396,10 @@ static int ip_vs_lblc_done_svc(struct ip_vs_service *svc)
del_timer_sync(&tbl->periodic_timer);
/* got to clean up table entries here */
- ip_vs_lblc_flush(tbl);
+ ip_vs_lblc_flush(svc);
/* release the table itself */
- kfree(tbl);
+ kfree_rcu(tbl, rcu_head);
IP_VS_DBG(6, "LBLC hash table (memory=%Zdbytes) released\n",
sizeof(*tbl));
@@ -408,7 +425,7 @@ __ip_vs_lblc_schedule(struct ip_vs_service *svc)
* The server with weight=0 is quiesced and will not receive any
* new connection.
*/
- list_for_each_entry(dest, &svc->destinations, n_list) {
+ list_for_each_entry_rcu(dest, &svc->destinations, n_list) {
if (dest->flags & IP_VS_DEST_F_OVERLOAD)
continue;
if (atomic_read(&dest->weight) > 0) {
@@ -423,7 +440,7 @@ __ip_vs_lblc_schedule(struct ip_vs_service *svc)
* Find the destination with the least load.
*/
nextstage:
- list_for_each_entry_continue(dest, &svc->destinations, n_list) {
+ list_for_each_entry_continue_rcu(dest, &svc->destinations, n_list) {
if (dest->flags & IP_VS_DEST_F_OVERLOAD)
continue;
@@ -457,7 +474,7 @@ is_overloaded(struct ip_vs_dest *dest, struct ip_vs_service *svc)
if (atomic_read(&dest->activeconns) > atomic_read(&dest->weight)) {
struct ip_vs_dest *d;
- list_for_each_entry(d, &svc->destinations, n_list) {
+ list_for_each_entry_rcu(d, &svc->destinations, n_list) {
if (atomic_read(&d->activeconns)*2
< atomic_read(&d->weight)) {
return 1;
@@ -484,7 +501,6 @@ ip_vs_lblc_schedule(struct ip_vs_service *svc, const struct sk_buff *skb)
IP_VS_DBG(6, "%s(): Scheduling...\n", __func__);
/* First look in our cache */
- read_lock(&svc->sched_lock);
en = ip_vs_lblc_get(svc->af, tbl, &iph.daddr);
if (en) {
/* We only hold a read lock, but this is atomic */
@@ -499,14 +515,11 @@ ip_vs_lblc_schedule(struct ip_vs_service *svc, const struct sk_buff *skb)
* free up entries from the trash at any time.
*/
- if (en->dest->flags & IP_VS_DEST_F_AVAILABLE)
- dest = en->dest;
+ dest = rcu_dereference(en->dest);
+ if ((dest->flags & IP_VS_DEST_F_AVAILABLE) &&
+ atomic_read(&dest->weight) > 0 && !is_overloaded(dest, svc))
+ goto out;
}
- read_unlock(&svc->sched_lock);
-
- /* If the destination has a weight and is not overloaded, use it */
- if (dest && atomic_read(&dest->weight) > 0 && !is_overloaded(dest, svc))
- goto out;
/* No cache entry or it is invalid, time to schedule */
dest = __ip_vs_lblc_schedule(svc);
@@ -517,7 +530,8 @@ ip_vs_lblc_schedule(struct ip_vs_service *svc, const struct sk_buff *skb)
/* If we fail to create a cache entry, we'll just use the valid dest */
write_lock(&svc->sched_lock);
- ip_vs_lblc_new(tbl, &iph.daddr, dest);
+ if (!tbl->dead)
+ ip_vs_lblc_new(tbl, &iph.daddr, dest);
write_unlock(&svc->sched_lock);
out:
--
1.7.3.4
--
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