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ipvs: convert lblcr scheduler to rcu

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The schedule method now needs _rcu list-traversal
primitive for svc->destinations. The read_lock for sched_lock is
removed. The set.lock is removed because now it is used in
rare cases, mostly under sched_lock.

Signed-off-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: Simon Horman <horms@verge.net.au>
This commit is contained in:
Julian Anastasov 2013-03-22 11:46:41 +02:00 committed by Pablo Neira Ayuso
parent c2a4ffb70e
commit c5549571f9
1 changed files with 90 additions and 81 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

155
net/netfilter/ipvs/ip_vs_lblcr.c
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@ -89,40 +89,44 @@
*/
struct ip_vs_dest_set_elem {
struct list_head list; /* list link */
struct ip_vs_dest *dest; /* destination server */
struct ip_vs_dest __rcu *dest; /* destination server */
struct rcu_head rcu_head;
};
struct ip_vs_dest_set {
atomic_t size; /* set size */
unsigned long lastmod; /* last modified time */
struct list_head list; /* destination list */
rwlock_t lock; /* lock for this list */
};
static struct ip_vs_dest_set_elem *
ip_vs_dest_set_insert(struct ip_vs_dest_set *set, struct ip_vs_dest *dest)
static void ip_vs_dest_set_insert(struct ip_vs_dest_set *set,
struct ip_vs_dest *dest, bool check)
{
struct ip_vs_dest_set_elem *e;
if (check) {
list_for_each_entry(e, &set->list, list) {
if (e->dest == dest)
struct ip_vs_dest *d;
d = rcu_dereference_protected(e->dest, 1);
if (d == dest)
/* already existed */
return NULL;
return;
}
}
e = kmalloc(sizeof(*e), GFP_ATOMIC);
if (e == NULL)
return NULL;
return;
atomic_inc(&dest->refcnt);
e->dest = dest;
ip_vs_dest_hold(dest);
RCU_INIT_POINTER(e->dest, dest);
list_add(&e->list, &set->list);
list_add_rcu(&e->list, &set->list);
atomic_inc(&set->size);
set->lastmod = jiffies;
return e;
}
static void
@ -131,13 +135,16 @@ ip_vs_dest_set_erase(struct ip_vs_dest_set *set, struct ip_vs_dest *dest)
struct ip_vs_dest_set_elem *e;
list_for_each_entry(e, &set->list, list) {
if (e->dest == dest) {
struct ip_vs_dest *d;
d = rcu_dereference_protected(e->dest, 1);
if (d == dest) {
/* HIT */
atomic_dec(&set->size);
set->lastmod = jiffies;
atomic_dec(&e->dest->refcnt);
list_del(&e->list);
kfree(e);
ip_vs_dest_put(dest);
list_del_rcu(&e->list);
kfree_rcu(e, rcu_head);
break;
}
}
@ -147,17 +154,18 @@ static void ip_vs_dest_set_eraseall(struct ip_vs_dest_set *set)
{
struct ip_vs_dest_set_elem *e, *ep;
write_lock(&set->lock);
list_for_each_entry_safe(e, ep, &set->list, list) {
struct ip_vs_dest *d;
d = rcu_dereference_protected(e->dest, 1);
/*
* We don't kfree dest because it is referred either
* by its service or by the trash dest list.
*/
atomic_dec(&e->dest->refcnt);
list_del(&e->list);
kfree(e);
ip_vs_dest_put(d);
list_del_rcu(&e->list);
kfree_rcu(e, rcu_head);
}
write_unlock(&set->lock);
}
/* get weighted least-connection node in the destination set */
@ -171,8 +179,8 @@ static inline struct ip_vs_dest *ip_vs_dest_set_min(struct ip_vs_dest_set *set)
return NULL;
/* select the first destination server, whose weight > 0 */
list_for_each_entry(e, &set->list, list) {
least = e->dest;
list_for_each_entry_rcu(e, &set->list, list) {
least = rcu_dereference(e->dest);
if (least->flags & IP_VS_DEST_F_OVERLOAD)
continue;
@ -186,8 +194,8 @@ static inline struct ip_vs_dest *ip_vs_dest_set_min(struct ip_vs_dest_set *set)
/* find the destination with the weighted least load */
nextstage:
list_for_each_entry(e, &set->list, list) {
dest = e->dest;
list_for_each_entry_continue_rcu(e, &set->list, list) {
dest = rcu_dereference(e->dest);
if (dest->flags & IP_VS_DEST_F_OVERLOAD)
continue;
@ -224,7 +232,7 @@ static inline struct ip_vs_dest *ip_vs_dest_set_max(struct ip_vs_dest_set *set)
/* select the first destination server, whose weight > 0 */
list_for_each_entry(e, &set->list, list) {
most = e->dest;
most = rcu_dereference_protected(e->dest, 1);
if (atomic_read(&most->weight) > 0) {
moh = ip_vs_dest_conn_overhead(most);
goto nextstage;
@ -234,8 +242,8 @@ static inline struct ip_vs_dest *ip_vs_dest_set_max(struct ip_vs_dest_set *set)
/* find the destination with the weighted most load */
nextstage:
list_for_each_entry(e, &set->list, list) {
dest = e->dest;
list_for_each_entry_continue(e, &set->list, list) {
dest = rcu_dereference_protected(e->dest, 1);
doh = ip_vs_dest_conn_overhead(dest);
/* moh/mw < doh/dw ==> moh*dw < doh*mw, where mw,dw>0 */
if ((moh * atomic_read(&dest->weight) <
@ -262,11 +270,12 @@ static inline struct ip_vs_dest *ip_vs_dest_set_max(struct ip_vs_dest_set *set)
* IP address and its destination server set
*/
struct ip_vs_lblcr_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_set set; /* destination server set */
unsigned long lastuse; /* last used time */
struct rcu_head rcu_head;
};
@ -274,12 +283,14 @@ struct ip_vs_lblcr_entry {
* IPVS lblcr hash table
*/
struct ip_vs_lblcr_table {
struct list_head bucket[IP_VS_LBLCR_TAB_SIZE]; /* hash bucket */
struct rcu_head rcu_head;
struct hlist_head __rcu bucket[IP_VS_LBLCR_TAB_SIZE]; /* hash bucket */
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;
};
@ -302,9 +313,9 @@ static ctl_table vs_vars_table[] = {
static inline void ip_vs_lblcr_free(struct ip_vs_lblcr_entry *en)
{
list_del(&en->list);
hlist_del_rcu(&en->list);
ip_vs_dest_set_eraseall(&en->set);
kfree(en);
kfree_rcu(en, rcu_head);
}
@ -334,15 +345,12 @@ ip_vs_lblcr_hash(struct ip_vs_lblcr_table *tbl, struct ip_vs_lblcr_entry *en)
{
unsigned int hash = ip_vs_lblcr_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_lblcr_entry associated with supplied parameters. Called under
* read lock.
*/
/* Get ip_vs_lblcr_entry associated with supplied parameters. */
static inline struct ip_vs_lblcr_entry *
ip_vs_lblcr_get(int af, struct ip_vs_lblcr_table *tbl,
const union nf_inet_addr *addr)
@ -350,7 +358,7 @@ ip_vs_lblcr_get(int af, struct ip_vs_lblcr_table *tbl,
unsigned int hash = ip_vs_lblcr_hashkey(af, addr);
struct ip_vs_lblcr_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;
@ -381,14 +389,14 @@ ip_vs_lblcr_new(struct ip_vs_lblcr_table *tbl, const union nf_inet_addr *daddr,
/* initialize its dest set */
atomic_set(&(en->set.size), 0);
INIT_LIST_HEAD(&en->set.list);
rwlock_init(&en->set.lock);
ip_vs_dest_set_insert(&en->set, dest, false);
ip_vs_lblcr_hash(tbl, en);
return en;
}
write_lock(&en->set.lock);
ip_vs_dest_set_insert(&en->set, dest);
write_unlock(&en->set.lock);
ip_vs_dest_set_insert(&en->set, dest, true);
return en;
}
@ -397,17 +405,21 @@ ip_vs_lblcr_new(struct ip_vs_lblcr_table *tbl, const union nf_inet_addr *daddr,
/*
* Flush all the entries of the specified table.
*/
static void ip_vs_lblcr_flush(struct ip_vs_lblcr_table *tbl)
static void ip_vs_lblcr_flush(struct ip_vs_service *svc)
{
struct ip_vs_lblcr_table *tbl = svc->sched_data;
int i;
struct ip_vs_lblcr_entry *en, *nxt;
struct ip_vs_lblcr_entry *en;
struct hlist_node *next;
/* No locking required, only called during cleanup. */
write_lock_bh(&svc->sched_lock);
tbl->dead = 1;
for (i=0; i<IP_VS_LBLCR_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_lblcr_free(en);
}
}
write_unlock_bh(&svc->sched_lock);
}
static int sysctl_lblcr_expiration(struct ip_vs_service *svc)
@ -425,13 +437,14 @@ static inline void ip_vs_lblcr_full_check(struct ip_vs_service *svc)
struct ip_vs_lblcr_table *tbl = svc->sched_data;
unsigned long now = jiffies;
int i, j;
struct ip_vs_lblcr_entry *en, *nxt;
struct ip_vs_lblcr_entry *en;
struct hlist_node *next;
for (i=0, j=tbl->rover; i<IP_VS_LBLCR_TAB_SIZE; i++) {
j = (j + 1) & IP_VS_LBLCR_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_after(en->lastuse +
sysctl_lblcr_expiration(svc), now))
continue;
@ -463,7 +476,8 @@ static void ip_vs_lblcr_check_expire(unsigned long data)
unsigned long now = jiffies;
int goal;
int i, j;
struct ip_vs_lblcr_entry *en, *nxt;
struct ip_vs_lblcr_entry *en;
struct hlist_node *next;
if ((tbl->counter % COUNT_FOR_FULL_EXPIRATION) == 0) {
/* do full expiration check */
@ -485,7 +499,7 @@ static void ip_vs_lblcr_check_expire(unsigned long data)
j = (j + 1) & IP_VS_LBLCR_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;
@ -523,11 +537,12 @@ static int ip_vs_lblcr_init_svc(struct ip_vs_service *svc)
* Initialize the hash buckets
*/
for (i=0; i<IP_VS_LBLCR_TAB_SIZE; i++) {
INIT_LIST_HEAD(&tbl->bucket[i]);
INIT_HLIST_HEAD(&tbl->bucket[i]);
}
tbl->max_size = IP_VS_LBLCR_TAB_SIZE*16;
tbl->rover = 0;
tbl->counter = 1;
tbl->dead = 0;
/*
* Hook periodic timer for garbage collection
@ -548,10 +563,10 @@ static int ip_vs_lblcr_done_svc(struct ip_vs_service *svc)
del_timer_sync(&tbl->periodic_timer);
/* got to clean up table entries here */
ip_vs_lblcr_flush(tbl);
ip_vs_lblcr_flush(svc);
/* release the table itself */
kfree(tbl);
kfree_rcu(tbl, rcu_head);
IP_VS_DBG(6, "LBLCR hash table (memory=%Zdbytes) released\n",
sizeof(*tbl));
@ -577,7 +592,7 @@ __ip_vs_lblcr_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;
@ -593,7 +608,7 @@ __ip_vs_lblcr_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;
@ -627,7 +642,7 @@ 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;
@ -646,7 +661,7 @@ ip_vs_lblcr_schedule(struct ip_vs_service *svc, const struct sk_buff *skb)
{
struct ip_vs_lblcr_table *tbl = svc->sched_data;
struct ip_vs_iphdr iph;
struct ip_vs_dest *dest = NULL;
struct ip_vs_dest *dest;
struct ip_vs_lblcr_entry *en;
ip_vs_fill_iph_addr_only(svc->af, skb, &iph);
@ -654,53 +669,46 @@ ip_vs_lblcr_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_lblcr_get(svc->af, tbl, &iph.daddr);
if (en) {
/* We only hold a read lock, but this is atomic */
en->lastuse = jiffies;
/* Get the least loaded destination */
read_lock(&en->set.lock);
dest = ip_vs_dest_set_min(&en->set);
read_unlock(&en->set.lock);
/* More than one destination + enough time passed by, cleanup */
if (atomic_read(&en->set.size) > 1 &&
time_after(jiffies, en->set.lastmod +
sysctl_lblcr_expiration(svc))) {
write_lock(&svc->sched_lock);
if (atomic_read(&en->set.size) > 1) {
struct ip_vs_dest *m;
write_lock(&en->set.lock);
m = ip_vs_dest_set_max(&en->set);
if (m)
ip_vs_dest_set_erase(&en->set, m);
write_unlock(&en->set.lock);
}
write_unlock(&svc->sched_lock);
}
/* If the destination is not overloaded, use it */
if (dest && !is_overloaded(dest, svc)) {
read_unlock(&svc->sched_lock);
if (dest && !is_overloaded(dest, svc))
goto out;
}
/* The cache entry is invalid, time to schedule */
dest = __ip_vs_lblcr_schedule(svc);
if (!dest) {
ip_vs_scheduler_err(svc, "no destination available");
read_unlock(&svc->sched_lock);
return NULL;
}
/* Update our cache entry */
write_lock(&en->set.lock);
ip_vs_dest_set_insert(&en->set, dest);
write_unlock(&en->set.lock);
}
read_unlock(&svc->sched_lock);
if (dest)
write_lock(&svc->sched_lock);
if (!tbl->dead)
ip_vs_dest_set_insert(&en->set, dest, true);
write_unlock(&svc->sched_lock);
goto out;
}
/* No cache entry, time to schedule */
dest = __ip_vs_lblcr_schedule(svc);
@ -711,6 +719,7 @@ ip_vs_lblcr_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);
if (!tbl->dead)
ip_vs_lblcr_new(tbl, &iph.daddr, dest);
write_unlock(&svc->sched_lock);