Commit 117a8cde authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

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: default avatarEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 9bef83ed

net/ipv4/fib_hash.c

+38 −19
Original line number Diff line number Diff line
@@ -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)	*/
@@ -74,7 +74,7 @@ struct fn_zone { 


struct fn_hash {

	struct fn_zone		*fn_zones[33];

	struct fn_zone	*fn_zone_list;

	struct fn_zone __rcu	*fn_zone_list;

};



static inline u32 fn_hash(__be32 key, struct fn_zone *fz)
@@ -222,18 +222,18 @@ fn_new_zone(struct fn_hash *table, int z) 
	for (i = z + 1; i <= 32; i++)

		if (table->fn_zones[i])

			break;

	write_lock_bh(&fib_hash_lock);

	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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