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authorEric Dumazet <eric.dumazet@gmail.com>2010-10-04 06:15:44 +0000
committerDavid S. Miller <davem@davemloft.net>2010-10-05 14:54:36 -0700
commitd6bf781712a1d25cc8987036b3a48535b331eb91 (patch)
treecf83ab68ef2519576578d8336a43cc13cd375cde /net/core/neighbour.c
parent110b2499370c401cdcc7c63e481084467291d556 (diff)
net neigh: RCU conversion of neigh hash table
David This is the first step for RCU conversion of neigh code. Next patches will convert hash_buckets[] and "struct neighbour" to RCU protected objects. Thanks [PATCH net-next] net neigh: RCU conversion of neigh hash table Instead of storing hash_buckets, hash_mask and hash_rnd in "struct neigh_table", a new structure is defined : struct neigh_hash_table { struct neighbour **hash_buckets; unsigned int hash_mask; __u32 hash_rnd; struct rcu_head rcu; }; And "struct neigh_table" has an RCU protected pointer to such a neigh_hash_table. This means the signature of (*hash)() function changed: We need to add a third parameter with the actual hash_rnd value, since this is not anymore a neigh_table field. Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/core/neighbour.c')
-rw-r--r--net/core/neighbour.c219
1 files changed, 137 insertions, 82 deletions
diff --git a/net/core/neighbour.c b/net/core/neighbour.c
index d6996e072a41..dd8920e4f508 100644
--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c
@@ -131,14 +131,17 @@ static int neigh_forced_gc(struct neigh_table *tbl)
{
int shrunk = 0;
int i;
+ struct neigh_hash_table *nht;
NEIGH_CACHE_STAT_INC(tbl, forced_gc_runs);
write_lock_bh(&tbl->lock);
- for (i = 0; i <= tbl->hash_mask; i++) {
+ nht = rcu_dereference_protected(tbl->nht,
+ lockdep_is_held(&tbl->lock));
+ for (i = 0; i <= nht->hash_mask; i++) {
struct neighbour *n, **np;
- np = &tbl->hash_buckets[i];
+ np = &nht->hash_buckets[i];
while ((n = *np) != NULL) {
/* Neighbour record may be discarded if:
* - nobody refers to it.
@@ -199,9 +202,13 @@ static void pneigh_queue_purge(struct sk_buff_head *list)
static void neigh_flush_dev(struct neigh_table *tbl, struct net_device *dev)
{
int i;
+ struct neigh_hash_table *nht;
- for (i = 0; i <= tbl->hash_mask; i++) {
- struct neighbour *n, **np = &tbl->hash_buckets[i];
+ nht = rcu_dereference_protected(tbl->nht,
+ lockdep_is_held(&tbl->lock));
+
+ for (i = 0; i <= nht->hash_mask; i++) {
+ struct neighbour *n, **np = &nht->hash_buckets[i];
while ((n = *np) != NULL) {
if (dev && n->dev != dev) {
@@ -297,64 +304,81 @@ out_entries:
goto out;
}
-static struct neighbour **neigh_hash_alloc(unsigned int entries)
+static struct neigh_hash_table *neigh_hash_alloc(unsigned int entries)
{
- unsigned long size = entries * sizeof(struct neighbour *);
- struct neighbour **ret;
+ size_t size = entries * sizeof(struct neighbour *);
+ struct neigh_hash_table *ret;
+ struct neighbour **buckets;
- if (size <= PAGE_SIZE) {
- ret = kzalloc(size, GFP_ATOMIC);
- } else {
- ret = (struct neighbour **)
- __get_free_pages(GFP_ATOMIC|__GFP_ZERO, get_order(size));
+ ret = kmalloc(sizeof(*ret), GFP_ATOMIC);
+ if (!ret)
+ return NULL;
+ if (size <= PAGE_SIZE)
+ buckets = kzalloc(size, GFP_ATOMIC);
+ else
+ buckets = (struct neighbour **)
+ __get_free_pages(GFP_ATOMIC | __GFP_ZERO,
+ get_order(size));
+ if (!buckets) {
+ kfree(ret);
+ return NULL;
}
+ ret->hash_buckets = buckets;
+ ret->hash_mask = entries - 1;
+ get_random_bytes(&ret->hash_rnd, sizeof(ret->hash_rnd));
return ret;
}
-static void neigh_hash_free(struct neighbour **hash, unsigned int entries)
+static void neigh_hash_free_rcu(struct rcu_head *head)
{
- unsigned long size = entries * sizeof(struct neighbour *);
+ struct neigh_hash_table *nht = container_of(head,
+ struct neigh_hash_table,
+ rcu);
+ size_t size = (nht->hash_mask + 1) * sizeof(struct neighbour *);
+ struct neighbour **buckets = nht->hash_buckets;
if (size <= PAGE_SIZE)
- kfree(hash);
+ kfree(buckets);
else
- free_pages((unsigned long)hash, get_order(size));
+ free_pages((unsigned long)buckets, get_order(size));
+ kfree(nht);
}
-static void neigh_hash_grow(struct neigh_table *tbl, unsigned long new_entries)
+static struct neigh_hash_table *neigh_hash_grow(struct neigh_table *tbl,
+ unsigned long new_entries)
{
- struct neighbour **new_hash, **old_hash;
- unsigned int i, new_hash_mask, old_entries;
+ unsigned int i, hash;
+ struct neigh_hash_table *new_nht, *old_nht;
NEIGH_CACHE_STAT_INC(tbl, hash_grows);
BUG_ON(!is_power_of_2(new_entries));
- new_hash = neigh_hash_alloc(new_entries);
- if (!new_hash)
- return;
+ old_nht = rcu_dereference_protected(tbl->nht,
+ lockdep_is_held(&tbl->lock));
+ new_nht = neigh_hash_alloc(new_entries);
+ if (!new_nht)
+ return old_nht;
- old_entries = tbl->hash_mask + 1;
- new_hash_mask = new_entries - 1;
- old_hash = tbl->hash_buckets;
-
- get_random_bytes(&tbl->hash_rnd, sizeof(tbl->hash_rnd));
- for (i = 0; i < old_entries; i++) {
+ for (i = 0; i <= old_nht->hash_mask; i++) {
struct neighbour *n, *next;
- for (n = old_hash[i]; n; n = next) {
- unsigned int hash_val = tbl->hash(n->primary_key, n->dev);
+ for (n = old_nht->hash_buckets[i];
+ n != NULL;
+ n = next) {
+ hash = tbl->hash(n->primary_key, n->dev,
+ new_nht->hash_rnd);
- hash_val &= new_hash_mask;
+ hash &= new_nht->hash_mask;
next = n->next;
- n->next = new_hash[hash_val];
- new_hash[hash_val] = n;
+ n->next = new_nht->hash_buckets[hash];
+ new_nht->hash_buckets[hash] = n;
}
}
- tbl->hash_buckets = new_hash;
- tbl->hash_mask = new_hash_mask;
- neigh_hash_free(old_hash, old_entries);
+ rcu_assign_pointer(tbl->nht, new_nht);
+ call_rcu(&old_nht->rcu, neigh_hash_free_rcu);
+ return new_nht;
}
struct neighbour *neigh_lookup(struct neigh_table *tbl, const void *pkey,
@@ -363,19 +387,23 @@ struct neighbour *neigh_lookup(struct neigh_table *tbl, const void *pkey,
struct neighbour *n;
int key_len = tbl->key_len;
u32 hash_val;
+ struct neigh_hash_table *nht;
NEIGH_CACHE_STAT_INC(tbl, lookups);
- read_lock_bh(&tbl->lock);
- hash_val = tbl->hash(pkey, dev);
- for (n = tbl->hash_buckets[hash_val & tbl->hash_mask]; n; n = n->next) {
+ rcu_read_lock_bh();
+ nht = rcu_dereference_bh(tbl->nht);
+ hash_val = tbl->hash(pkey, dev, nht->hash_rnd) & nht->hash_mask;
+ read_lock(&tbl->lock);
+ for (n = nht->hash_buckets[hash_val]; n; n = n->next) {
if (dev == n->dev && !memcmp(n->primary_key, pkey, key_len)) {
neigh_hold(n);
NEIGH_CACHE_STAT_INC(tbl, hits);
break;
}
}
- read_unlock_bh(&tbl->lock);
+ read_unlock(&tbl->lock);
+ rcu_read_unlock_bh();
return n;
}
EXPORT_SYMBOL(neigh_lookup);
@@ -386,12 +414,15 @@ struct neighbour *neigh_lookup_nodev(struct neigh_table *tbl, struct net *net,
struct neighbour *n;
int key_len = tbl->key_len;
u32 hash_val;
+ struct neigh_hash_table *nht;
NEIGH_CACHE_STAT_INC(tbl, lookups);
- read_lock_bh(&tbl->lock);
- hash_val = tbl->hash(pkey, NULL);
- for (n = tbl->hash_buckets[hash_val & tbl->hash_mask]; n; n = n->next) {
+ rcu_read_lock_bh();
+ nht = rcu_dereference_bh(tbl->nht);
+ hash_val = tbl->hash(pkey, NULL, nht->hash_rnd) & nht->hash_mask;
+ read_lock(&tbl->lock);
+ for (n = nht->hash_buckets[hash_val]; n; n = n->next) {
if (!memcmp(n->primary_key, pkey, key_len) &&
net_eq(dev_net(n->dev), net)) {
neigh_hold(n);
@@ -399,7 +430,8 @@ struct neighbour *neigh_lookup_nodev(struct neigh_table *tbl, struct net *net,
break;
}
}
- read_unlock_bh(&tbl->lock);
+ read_unlock(&tbl->lock);
+ rcu_read_unlock_bh();
return n;
}
EXPORT_SYMBOL(neigh_lookup_nodev);
@@ -411,6 +443,7 @@ struct neighbour *neigh_create(struct neigh_table *tbl, const void *pkey,
int key_len = tbl->key_len;
int error;
struct neighbour *n1, *rc, *n = neigh_alloc(tbl);
+ struct neigh_hash_table *nht;
if (!n) {
rc = ERR_PTR(-ENOBUFS);
@@ -437,18 +470,20 @@ struct neighbour *neigh_create(struct neigh_table *tbl, const void *pkey,
n->confirmed = jiffies - (n->parms->base_reachable_time << 1);
write_lock_bh(&tbl->lock);
+ nht = rcu_dereference_protected(tbl->nht,
+ lockdep_is_held(&tbl->lock));
- if (atomic_read(&tbl->entries) > (tbl->hash_mask + 1))
- neigh_hash_grow(tbl, (tbl->hash_mask + 1) << 1);
+ if (atomic_read(&tbl->entries) > (nht->hash_mask + 1))
+ nht = neigh_hash_grow(tbl, (nht->hash_mask + 1) << 1);
- hash_val = tbl->hash(pkey, dev) & tbl->hash_mask;
+ hash_val = tbl->hash(pkey, dev, nht->hash_rnd) & nht->hash_mask;
if (n->parms->dead) {
rc = ERR_PTR(-EINVAL);
goto out_tbl_unlock;
}
- for (n1 = tbl->hash_buckets[hash_val]; n1; n1 = n1->next) {
+ for (n1 = nht->hash_buckets[hash_val]; n1; n1 = n1->next) {
if (dev == n1->dev && !memcmp(n1->primary_key, pkey, key_len)) {
neigh_hold(n1);
rc = n1;
@@ -456,8 +491,8 @@ struct neighbour *neigh_create(struct neigh_table *tbl, const void *pkey,
}
}
- n->next = tbl->hash_buckets[hash_val];
- tbl->hash_buckets[hash_val] = n;
+ n->next = nht->hash_buckets[hash_val];
+ nht->hash_buckets[hash_val] = n;
n->dead = 0;
neigh_hold(n);
write_unlock_bh(&tbl->lock);
@@ -698,10 +733,13 @@ static void neigh_periodic_work(struct work_struct *work)
struct neigh_table *tbl = container_of(work, struct neigh_table, gc_work.work);
struct neighbour *n, **np;
unsigned int i;
+ struct neigh_hash_table *nht;
NEIGH_CACHE_STAT_INC(tbl, periodic_gc_runs);
write_lock_bh(&tbl->lock);
+ nht = rcu_dereference_protected(tbl->nht,
+ lockdep_is_held(&tbl->lock));
/*
* periodically recompute ReachableTime from random function
@@ -715,8 +753,8 @@ static void neigh_periodic_work(struct work_struct *work)
neigh_rand_reach_time(p->base_reachable_time);
}
- for (i = 0 ; i <= tbl->hash_mask; i++) {
- np = &tbl->hash_buckets[i];
+ for (i = 0 ; i <= nht->hash_mask; i++) {
+ np = &nht->hash_buckets[i];
while ((n = *np) != NULL) {
unsigned int state;
@@ -1438,17 +1476,14 @@ void neigh_table_init_no_netlink(struct neigh_table *tbl)
panic("cannot create neighbour proc dir entry");
#endif
- tbl->hash_mask = 1;
- tbl->hash_buckets = neigh_hash_alloc(tbl->hash_mask + 1);
+ tbl->nht = neigh_hash_alloc(8);
phsize = (PNEIGH_HASHMASK + 1) * sizeof(struct pneigh_entry *);
tbl->phash_buckets = kzalloc(phsize, GFP_KERNEL);
- if (!tbl->hash_buckets || !tbl->phash_buckets)
+ if (!tbl->nht || !tbl->phash_buckets)
panic("cannot allocate neighbour cache hashes");
- get_random_bytes(&tbl->hash_rnd, sizeof(tbl->hash_rnd));
-
rwlock_init(&tbl->lock);
INIT_DELAYED_WORK_DEFERRABLE(&tbl->gc_work, neigh_periodic_work);
schedule_delayed_work(&tbl->gc_work, tbl->parms.reachable_time);
@@ -1504,8 +1539,8 @@ int neigh_table_clear(struct neigh_table *tbl)
}
write_unlock(&neigh_tbl_lock);
- neigh_hash_free(tbl->hash_buckets, tbl->hash_mask + 1);
- tbl->hash_buckets = NULL;
+ call_rcu(&tbl->nht->rcu, neigh_hash_free_rcu);
+ tbl->nht = NULL;
kfree(tbl->phash_buckets);
tbl->phash_buckets = NULL;
@@ -1745,18 +1780,22 @@ static int neightbl_fill_info(struct sk_buff *skb, struct neigh_table *tbl,
unsigned long now = jiffies;
unsigned int flush_delta = now - tbl->last_flush;
unsigned int rand_delta = now - tbl->last_rand;
-
+ struct neigh_hash_table *nht;
struct ndt_config ndc = {
.ndtc_key_len = tbl->key_len,
.ndtc_entry_size = tbl->entry_size,
.ndtc_entries = atomic_read(&tbl->entries),
.ndtc_last_flush = jiffies_to_msecs(flush_delta),
.ndtc_last_rand = jiffies_to_msecs(rand_delta),
- .ndtc_hash_rnd = tbl->hash_rnd,
- .ndtc_hash_mask = tbl->hash_mask,
.ndtc_proxy_qlen = tbl->proxy_queue.qlen,
};
+ rcu_read_lock_bh();
+ nht = rcu_dereference_bh(tbl->nht);
+ ndc.ndtc_hash_rnd = nht->hash_rnd;
+ ndc.ndtc_hash_mask = nht->hash_mask;
+ rcu_read_unlock_bh();
+
NLA_PUT(skb, NDTA_CONFIG, sizeof(ndc), &ndc);
}
@@ -2088,14 +2127,18 @@ static int neigh_dump_table(struct neigh_table *tbl, struct sk_buff *skb,
struct neighbour *n;
int rc, h, s_h = cb->args[1];
int idx, s_idx = idx = cb->args[2];
+ struct neigh_hash_table *nht;
- read_lock_bh(&tbl->lock);
- for (h = 0; h <= tbl->hash_mask; h++) {
+ rcu_read_lock_bh();
+ nht = rcu_dereference_bh(tbl->nht);
+
+ read_lock(&tbl->lock);
+ for (h = 0; h <= nht->hash_mask; h++) {
if (h < s_h)
continue;
if (h > s_h)
s_idx = 0;
- for (n = tbl->hash_buckets[h], idx = 0; n; n = n->next) {
+ for (n = nht->hash_buckets[h], idx = 0; n; n = n->next) {
if (!net_eq(dev_net(n->dev), net))
continue;
if (idx < s_idx)
@@ -2104,7 +2147,6 @@ static int neigh_dump_table(struct neigh_table *tbl, struct sk_buff *skb,
cb->nlh->nlmsg_seq,
RTM_NEWNEIGH,
NLM_F_MULTI) <= 0) {
- read_unlock_bh(&tbl->lock);
rc = -1;
goto out;
}
@@ -2112,9 +2154,10 @@ static int neigh_dump_table(struct neigh_table *tbl, struct sk_buff *skb,
idx++;
}
}
- read_unlock_bh(&tbl->lock);
rc = skb->len;
out:
+ read_unlock(&tbl->lock);
+ rcu_read_unlock_bh();
cb->args[1] = h;
cb->args[2] = idx;
return rc;
@@ -2147,15 +2190,20 @@ static int neigh_dump_info(struct sk_buff *skb, struct netlink_callback *cb)
void neigh_for_each(struct neigh_table *tbl, void (*cb)(struct neighbour *, void *), void *cookie)
{
int chain;
+ struct neigh_hash_table *nht;
- read_lock_bh(&tbl->lock);
- for (chain = 0; chain <= tbl->hash_mask; chain++) {
+ rcu_read_lock_bh();
+ nht = rcu_dereference_bh(tbl->nht);
+
+ read_lock(&tbl->lock);
+ for (chain = 0; chain <= nht->hash_mask; chain++) {
struct neighbour *n;
- for (n = tbl->hash_buckets[chain]; n; n = n->next)
+ for (n = nht->hash_buckets[chain]; n; n = n->next)
cb(n, cookie);
}
- read_unlock_bh(&tbl->lock);
+ read_unlock(&tbl->lock);
+ rcu_read_unlock_bh();
}
EXPORT_SYMBOL(neigh_for_each);
@@ -2164,11 +2212,14 @@ void __neigh_for_each_release(struct neigh_table *tbl,
int (*cb)(struct neighbour *))
{
int chain;
+ struct neigh_hash_table *nht;
- for (chain = 0; chain <= tbl->hash_mask; chain++) {
+ nht = rcu_dereference_protected(tbl->nht,
+ lockdep_is_held(&tbl->lock));
+ for (chain = 0; chain <= nht->hash_mask; chain++) {
struct neighbour *n, **np;
- np = &tbl->hash_buckets[chain];
+ np = &nht->hash_buckets[chain];
while ((n = *np) != NULL) {
int release;
@@ -2193,13 +2244,13 @@ static struct neighbour *neigh_get_first(struct seq_file *seq)
{
struct neigh_seq_state *state = seq->private;
struct net *net = seq_file_net(seq);
- struct neigh_table *tbl = state->tbl;
+ struct neigh_hash_table *nht = state->nht;
struct neighbour *n = NULL;
int bucket = state->bucket;
state->flags &= ~NEIGH_SEQ_IS_PNEIGH;
- for (bucket = 0; bucket <= tbl->hash_mask; bucket++) {
- n = tbl->hash_buckets[bucket];
+ for (bucket = 0; bucket <= nht->hash_mask; bucket++) {
+ n = nht->hash_buckets[bucket];
while (n) {
if (!net_eq(dev_net(n->dev), net))
@@ -2234,7 +2285,7 @@ static struct neighbour *neigh_get_next(struct seq_file *seq,
{
struct neigh_seq_state *state = seq->private;
struct net *net = seq_file_net(seq);
- struct neigh_table *tbl = state->tbl;
+ struct neigh_hash_table *nht = state->nht;
if (state->neigh_sub_iter) {
void *v = state->neigh_sub_iter(state, n, pos);
@@ -2265,10 +2316,10 @@ static struct neighbour *neigh_get_next(struct seq_file *seq,
if (n)
break;
- if (++state->bucket > tbl->hash_mask)
+ if (++state->bucket > nht->hash_mask)
break;
- n = tbl->hash_buckets[state->bucket];
+ n = nht->hash_buckets[state->bucket];
}
if (n && pos)
@@ -2367,6 +2418,7 @@ static void *neigh_get_idx_any(struct seq_file *seq, loff_t *pos)
void *neigh_seq_start(struct seq_file *seq, loff_t *pos, struct neigh_table *tbl, unsigned int neigh_seq_flags)
__acquires(tbl->lock)
+ __acquires(rcu_bh)
{
struct neigh_seq_state *state = seq->private;
@@ -2374,8 +2426,9 @@ void *neigh_seq_start(struct seq_file *seq, loff_t *pos, struct neigh_table *tbl
state->bucket = 0;
state->flags = (neigh_seq_flags & ~NEIGH_SEQ_IS_PNEIGH);
- read_lock_bh(&tbl->lock);
-
+ rcu_read_lock_bh();
+ state->nht = rcu_dereference_bh(tbl->nht);
+ read_lock(&tbl->lock);
return *pos ? neigh_get_idx_any(seq, pos) : SEQ_START_TOKEN;
}
EXPORT_SYMBOL(neigh_seq_start);
@@ -2409,11 +2462,13 @@ EXPORT_SYMBOL(neigh_seq_next);
void neigh_seq_stop(struct seq_file *seq, void *v)
__releases(tbl->lock)
+ __releases(rcu_bh)
{
struct neigh_seq_state *state = seq->private;
struct neigh_table *tbl = state->tbl;
- read_unlock_bh(&tbl->lock);
+ read_unlock(&tbl->lock);
+ rcu_read_unlock_bh();
}
EXPORT_SYMBOL(neigh_seq_stop);