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Date: Fri, 15 Oct 2010 08:53:34 +0200
From: Eric Dumazet <eric.dumazet@...il.com>
To: David Miller <davem@...emloft.net>
Cc: netdev <netdev@...r.kernel.org>
Subject: [PATCH net-next 2/3] fib_hash: RCU conversion phase 1
First step for RCU conversion of fib_hash :
struct fn_zone are created and never deleted.
Very classic conversion, using rcu_assign_pointer(), rcu_dereference()
and rtnl_dereference() verbs.
__rcu markers on fz_next and fn_zone_list
They are created under RTNL, we dont need fib_hash_lock anymore in
fn_new_zone().
Signed-off-by: Eric Dumazet <eric.dumazet@...il.com>
---
net/ipv4/fib_hash.c | 57 ++++++++++++++++++++++++++++--------------
1 files changed, 38 insertions(+), 19 deletions(-)
diff --git a/net/ipv4/fib_hash.c b/net/ipv4/fib_hash.c
index 10001aa..04f05a9 100644
--- a/net/ipv4/fib_hash.c
+++ b/net/ipv4/fib_hash.c
@@ -57,7 +57,7 @@ struct fib_node {
#define EMBEDDED_HASH_SIZE (L1_CACHE_BYTES / sizeof(struct hlist_head))
struct fn_zone {
- struct fn_zone *fz_next; /* Next not empty zone */
+ struct fn_zone __rcu *fz_next; /* Next not empty zone */
struct hlist_head *fz_hash; /* Hash table pointer */
u32 fz_hashmask; /* (fz_divisor - 1) */
@@ -73,8 +73,8 @@ struct fn_zone {
};
struct fn_hash {
- struct fn_zone *fn_zones[33];
- struct fn_zone *fn_zone_list;
+ struct fn_zone *fn_zones[33];
+ struct fn_zone __rcu *fn_zone_list;
};
static inline u32 fn_hash(__be32 key, struct fn_zone *fz)
@@ -219,21 +219,21 @@ fn_new_zone(struct fn_hash *table, int z)
fz->fz_mask = inet_make_mask(z);
/* Find the first not empty zone with more specific mask */
- for (i=z+1; i<=32; i++)
+ for (i = z + 1; i <= 32; i++)
if (table->fn_zones[i])
break;
- write_lock_bh(&fib_hash_lock);
- if (i>32) {
+ if (i > 32) {
/* No more specific masks, we are the first. */
- fz->fz_next = table->fn_zone_list;
- table->fn_zone_list = fz;
+ rcu_assign_pointer(fz->fz_next,
+ rtnl_dereference(table->fn_zone_list));
+ rcu_assign_pointer(table->fn_zone_list, fz);
} else {
- fz->fz_next = table->fn_zones[i]->fz_next;
- table->fn_zones[i]->fz_next = fz;
+ rcu_assign_pointer(fz->fz_next,
+ rtnl_dereference(table->fn_zones[i]->fz_next));
+ rcu_assign_pointer(table->fn_zones[i]->fz_next, fz);
}
table->fn_zones[z] = fz;
fib_hash_genid++;
- write_unlock_bh(&fib_hash_lock);
return fz;
}
@@ -245,8 +245,11 @@ int fib_table_lookup(struct fib_table *tb,
struct fn_zone *fz;
struct fn_hash *t = (struct fn_hash *)tb->tb_data;
+ rcu_read_lock();
read_lock(&fib_hash_lock);
- for (fz = t->fn_zone_list; fz; fz = fz->fz_next) {
+ for (fz = rcu_dereference(t->fn_zone_list);
+ fz != NULL;
+ fz = rcu_dereference(fz->fz_next)) {
struct hlist_head *head;
struct hlist_node *node;
struct fib_node *f;
@@ -267,6 +270,7 @@ int fib_table_lookup(struct fib_table *tb,
err = 1;
out:
read_unlock(&fib_hash_lock);
+ rcu_read_unlock();
return err;
}
@@ -362,6 +366,7 @@ static struct fib_node *fib_find_node(struct fn_zone *fz, __be32 key)
return NULL;
}
+/* Caller must hold RTNL. */
int fib_table_insert(struct fib_table *tb, struct fib_config *cfg)
{
struct fn_hash *table = (struct fn_hash *) tb->tb_data;
@@ -657,13 +662,16 @@ static int fn_flush_list(struct fn_zone *fz, int idx)
return found;
}
+/* caller must hold RTNL. */
int fib_table_flush(struct fib_table *tb)
{
struct fn_hash *table = (struct fn_hash *) tb->tb_data;
struct fn_zone *fz;
int found = 0;
- for (fz = table->fn_zone_list; fz; fz = fz->fz_next) {
+ for (fz = rtnl_dereference(table->fn_zone_list);
+ fz != NULL;
+ fz = rtnl_dereference(fz->fz_next)) {
int i;
for (i = fz->fz_divisor - 1; i >= 0; i--)
@@ -741,23 +749,29 @@ fn_hash_dump_zone(struct sk_buff *skb, struct netlink_callback *cb,
int fib_table_dump(struct fib_table *tb, struct sk_buff *skb,
struct netlink_callback *cb)
{
- int m, s_m;
+ int m = 0, s_m;
struct fn_zone *fz;
struct fn_hash *table = (struct fn_hash *)tb->tb_data;
s_m = cb->args[2];
+ rcu_read_lock();
read_lock(&fib_hash_lock);
- for (fz = table->fn_zone_list, m=0; fz; fz = fz->fz_next, m++) {
- if (m < s_m) continue;
+ for (fz = rcu_dereference(table->fn_zone_list);
+ fz != NULL;
+ fz = rcu_dereference(fz->fz_next), m++) {
+ if (m < s_m)
+ continue;
if (fn_hash_dump_zone(skb, cb, tb, fz) < 0) {
cb->args[2] = m;
read_unlock(&fib_hash_lock);
+ rcu_read_unlock();
return -1;
}
memset(&cb->args[3], 0,
sizeof(cb->args) - 3*sizeof(cb->args[0]));
}
read_unlock(&fib_hash_lock);
+ rcu_read_unlock();
cb->args[2] = m;
return skb->len;
}
@@ -820,8 +834,9 @@ static struct fib_alias *fib_get_first(struct seq_file *seq)
iter->genid = fib_hash_genid;
iter->valid = 1;
- for (iter->zone = table->fn_zone_list; iter->zone;
- iter->zone = iter->zone->fz_next) {
+ for (iter->zone = rcu_dereference(table->fn_zone_list);
+ iter->zone != NULL;
+ iter->zone = rcu_dereference(iter->zone->fz_next)) {
int maxslot;
if (!iter->zone->fz_nent)
@@ -906,7 +921,7 @@ static struct fib_alias *fib_get_next(struct seq_file *seq)
}
}
- iter->zone = iter->zone->fz_next;
+ iter->zone = rcu_dereference(iter->zone->fz_next);
if (!iter->zone)
goto out;
@@ -946,9 +961,11 @@ static struct fib_alias *fib_get_idx(struct seq_file *seq, loff_t pos)
static void *fib_seq_start(struct seq_file *seq, loff_t *pos)
__acquires(fib_hash_lock)
+ __acquires(RCU)
{
void *v = NULL;
+ rcu_read_lock();
read_lock(&fib_hash_lock);
if (fib_get_table(seq_file_net(seq), RT_TABLE_MAIN))
v = *pos ? fib_get_idx(seq, *pos - 1) : SEQ_START_TOKEN;
@@ -963,8 +980,10 @@ static void *fib_seq_next(struct seq_file *seq, void *v, loff_t *pos)
static void fib_seq_stop(struct seq_file *seq, void *v)
__releases(fib_hash_lock)
+ __releases(RCU)
{
read_unlock(&fib_hash_lock);
+ rcu_read_unlock();
}
static unsigned fib_flag_trans(int type, __be32 mask, struct fib_info *fi)
--
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