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Commit ff302db9 authored by NeilBrown's avatar NeilBrown Committed by David S. Miller
Browse files

rhashtable: allow rht_bucket_var to return NULL. 



Rather than returning a pointer to a static nulls, rht_bucket_var()
now returns NULL if the bucket doesn't exist.
This will make the next patch, which stores a bitlock in the
bucket pointer, somewhat cleaner.

This change involves introducing __rht_bucket_nested() which is
like rht_bucket_nested(), but doesn't provide the static nulls,
and changing rht_bucket_nested() to call this and possible
provide a static nulls - as is still needed for the non-var case.

Signed-off-by: default avatarNeilBrown <neilb@suse.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 7a41c294

include/linux/rhashtable.h

+9 −2
Original line number Diff line number Diff line
@@ -265,6 +265,8 @@ void rhashtable_destroy(struct rhashtable *ht); 


struct rhash_head __rcu **rht_bucket_nested(const struct bucket_table *tbl,

					    unsigned int hash);

struct rhash_head __rcu **__rht_bucket_nested(const struct bucket_table *tbl,

					      unsigned int hash);

struct rhash_head __rcu **rht_bucket_nested_insert(struct rhashtable *ht,

						   struct bucket_table *tbl,

						   unsigned int hash);
@@ -294,7 +296,7 @@ static inline struct rhash_head __rcu *const *rht_bucket( 
static inline struct rhash_head __rcu **rht_bucket_var(

	struct bucket_table *tbl, unsigned int hash)

{

	return unlikely(tbl->nest) ? rht_bucket_nested(tbl, hash) :

	return unlikely(tbl->nest) ? __rht_bucket_nested(tbl, hash) :

				     &tbl->buckets[hash];

}
@@ -890,6 +892,8 @@ static inline int __rhashtable_remove_fast_one( 
	spin_lock_bh(lock);



	pprev = rht_bucket_var(tbl, hash);

	if (!pprev)

		goto out;

	rht_for_each_from(he, *pprev, tbl, hash) {

		struct rhlist_head *list;
@@ -934,6 +938,7 @@ static inline int __rhashtable_remove_fast_one( 
		break;

	}



out:

	spin_unlock_bh(lock);



	if (err > 0) {
@@ -1042,6 +1047,8 @@ static inline int __rhashtable_replace_fast( 
	spin_lock_bh(lock);



	pprev = rht_bucket_var(tbl, hash);

	if (!pprev)

		goto out;

	rht_for_each_from(he, *pprev, tbl, hash) {

		if (he != obj_old) {

			pprev = &he->next;
@@ -1053,7 +1060,7 @@ static inline int __rhashtable_replace_fast( 
		err = 0;

		break;

	}



out:

	spin_unlock_bh(lock);



	return err;

lib/rhashtable.c

+20 −9
Original line number Diff line number Diff line
@@ -237,8 +237,10 @@ static int rhashtable_rehash_one(struct rhashtable *ht, unsigned int old_hash) 
		goto out;



	err = -ENOENT;

	if (!pprev)

		goto out;



	rht_for_each(entry, old_tbl, old_hash) {

	rht_for_each_from(entry, *pprev, old_tbl, old_hash) {

		err = 0;

		next = rht_dereference_bucket(entry->next, old_tbl, old_hash);
@@ -496,6 +498,8 @@ static void *rhashtable_lookup_one(struct rhashtable *ht, 


	elasticity = RHT_ELASTICITY;

	pprev = rht_bucket_var(tbl, hash);

	if (!pprev)

		return ERR_PTR(-ENOENT);

	rht_for_each_from(head, *pprev, tbl, hash) {

		struct rhlist_head *list;

		struct rhlist_head *plist;
@@ -1161,11 +1165,10 @@ void rhashtable_destroy(struct rhashtable *ht) 
}

EXPORT_SYMBOL_GPL(rhashtable_destroy);



struct rhash_head __rcu **rht_bucket_nested(const struct bucket_table *tbl,

struct rhash_head __rcu **__rht_bucket_nested(const struct bucket_table *tbl,

					      unsigned int hash)

{

	const unsigned int shift = PAGE_SHIFT - ilog2(sizeof(void *));

	static struct rhash_head __rcu *rhnull;

	unsigned int index = hash & ((1 << tbl->nest) - 1);

	unsigned int size = tbl->size >> tbl->nest;

	unsigned int subhash = hash;
@@ -1183,15 +1186,23 @@ struct rhash_head __rcu **rht_bucket_nested(const struct bucket_table *tbl, 
		subhash >>= shift;

	}



	if (!ntbl) {

		if (!rhnull)

			INIT_RHT_NULLS_HEAD(rhnull);

		return &rhnull;

	}

	if (!ntbl)

		return NULL;



	return &ntbl[subhash].bucket;



}

EXPORT_SYMBOL_GPL(__rht_bucket_nested);



struct rhash_head __rcu **rht_bucket_nested(const struct bucket_table *tbl,

					    unsigned int hash)

{

	static struct rhash_head __rcu *rhnull;



	if (!rhnull)

		INIT_RHT_NULLS_HEAD(rhnull);

	return __rht_bucket_nested(tbl, hash) ?: &rhnull;

}

EXPORT_SYMBOL_GPL(rht_bucket_nested);



struct rhash_head __rcu **rht_bucket_nested_insert(struct rhashtable *ht,