From: Julian Anastasov Date: Fri, 22 Mar 2013 09:46:41 +0000 (+0200) Subject: ipvs: convert lblcr scheduler to rcu X-Git-Tag: MMI-PSA29.97-13-9~14469^2~243^2~28 X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=c5549571f975ab;p=GitHub%2FMotorolaMobilityLLC%2Fkernel-slsi.git ipvs: convert lblcr scheduler to rcu 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 Signed-off-by: Simon Horman --- diff --git a/net/netfilter/ipvs/ip_vs_lblcr.c b/net/netfilter/ipvs/ip_vs_lblcr.c index c03b6a3ade2f..c22f173d528c 100644 --- a/net/netfilter/ipvs/ip_vs_lblcr.c +++ b/net/netfilter/ipvs/ip_vs_lblcr.c @@ -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; - list_for_each_entry(e, &set->list, list) { - if (e->dest == dest) - /* already existed */ - return NULL; + if (check) { + list_for_each_entry(e, &set->list, list) { + struct ip_vs_dest *d; + + d = rcu_dereference_protected(e->dest, 1); + if (d == dest) + /* already existed */ + 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; ibucket[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; isched_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; ibucket[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 + + time_after(jiffies, en->set.lastmod + sysctl_lblcr_expiration(svc))) { - struct ip_vs_dest *m; + 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); + m = ip_vs_dest_set_max(&en->set); + if (m) + ip_vs_dest_set_erase(&en->set, m); + } + 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); @@ -711,7 +719,8 @@ 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); - ip_vs_lblcr_new(tbl, &iph.daddr, dest); + if (!tbl->dead) + ip_vs_lblcr_new(tbl, &iph.daddr, dest); write_unlock(&svc->sched_lock); out: