Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit ba6306e3 authored by Herbert Xu's avatar Herbert Xu Committed by David S. Miller
Browse files

rhashtable: Remove RCU marking from rhash_lock_head 



The opaque type rhash_lock_head should not be marked with __rcu
because it can never be dereferenced.  We should apply the RCU
marking when we turn it into a pointer which can be dereferenced.

This patch does exactly that.  This fixes a number of sparse
warnings as well as getting rid of some unnecessary RCU checking.

Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent c7d5ec26

include/linux/rhashtable.h

+32 −26
Original line number Diff line number Diff line
@@ -84,7 +84,7 @@ struct bucket_table { 


	struct lockdep_map	dep_map;



	struct rhash_lock_head __rcu *buckets[] ____cacheline_aligned_in_smp;

	struct rhash_lock_head *buckets[] ____cacheline_aligned_in_smp;

};



/*
@@ -261,11 +261,11 @@ void rhashtable_free_and_destroy(struct rhashtable *ht, 
				 void *arg);

void rhashtable_destroy(struct rhashtable *ht);



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

struct rhash_lock_head **rht_bucket_nested(const struct bucket_table *tbl,

					   unsigned int hash);

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

struct rhash_lock_head **__rht_bucket_nested(const struct bucket_table *tbl,

					     unsigned int hash);

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

struct rhash_lock_head **rht_bucket_nested_insert(struct rhashtable *ht,

						  struct bucket_table *tbl,

						  unsigned int hash);
@@ -284,21 +284,21 @@ struct rhash_lock_head __rcu **rht_bucket_nested_insert(struct rhashtable *ht, 
#define rht_entry(tpos, pos, member) \

	({ tpos = container_of(pos, typeof(*tpos), member); 1; })



static inline struct rhash_lock_head __rcu *const *rht_bucket(

static inline struct rhash_lock_head *const *rht_bucket(

	const struct bucket_table *tbl, unsigned int hash)

{

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

				     &tbl->buckets[hash];

}



static inline struct rhash_lock_head __rcu **rht_bucket_var(

static inline struct rhash_lock_head **rht_bucket_var(

	struct bucket_table *tbl, unsigned int hash)

{

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

				     &tbl->buckets[hash];

}



static inline struct rhash_lock_head __rcu **rht_bucket_insert(

static inline struct rhash_lock_head **rht_bucket_insert(

	struct rhashtable *ht, struct bucket_table *tbl, unsigned int hash)

{

	return unlikely(tbl->nest) ? rht_bucket_nested_insert(ht, tbl, hash) :
@@ -349,6 +349,12 @@ static inline void rht_unlock(struct bucket_table *tbl, 
	local_bh_enable();

}



static inline struct rhash_head __rcu *__rht_ptr(

	struct rhash_lock_head *const *bkt)

{

	return (struct rhash_head __rcu *)((unsigned long)*bkt & ~BIT(0));

}



/*

 * Where 'bkt' is a bucket and might be locked:

 *   rht_ptr() dereferences that pointer and clears the lock bit.
@@ -356,30 +362,30 @@ static inline void rht_unlock(struct bucket_table *tbl, 
 *            access is guaranteed, such as when destroying the table.

 */

static inline struct rhash_head *rht_ptr(

	struct rhash_lock_head __rcu * const *bkt,

	struct rhash_lock_head *const *bkt,

	struct bucket_table *tbl,

	unsigned int hash)

{

	const struct rhash_lock_head *p =

		rht_dereference_bucket_rcu(*bkt, tbl, hash);

	struct rhash_head __rcu *p = __rht_ptr(bkt);



	if ((((unsigned long)p) & ~BIT(0)) == 0)

	if (!p)

		return RHT_NULLS_MARKER(bkt);

	return (void *)(((unsigned long)p) & ~BIT(0));



	return rht_dereference_bucket_rcu(p, tbl, hash);

}



static inline struct rhash_head *rht_ptr_exclusive(

	struct rhash_lock_head __rcu * const *bkt)

	struct rhash_lock_head *const *bkt)

{

	const struct rhash_lock_head *p =

		rcu_dereference_protected(*bkt, 1);

	struct rhash_head __rcu *p = __rht_ptr(bkt);



	if (!p)

		return RHT_NULLS_MARKER(bkt);

	return (void *)(((unsigned long)p) & ~BIT(0));



	return rcu_dereference_protected(p, 1);

}



static inline void rht_assign_locked(struct rhash_lock_head __rcu **bkt,

static inline void rht_assign_locked(struct rhash_lock_head **bkt,

				     struct rhash_head *obj)

{

	struct rhash_head __rcu **p = (struct rhash_head __rcu **)bkt;
@@ -390,7 +396,7 @@ static inline void rht_assign_locked(struct rhash_lock_head __rcu **bkt, 
}



static inline void rht_assign_unlock(struct bucket_table *tbl,

				     struct rhash_lock_head __rcu **bkt,

				     struct rhash_lock_head **bkt,

				     struct rhash_head *obj)

{

	struct rhash_head __rcu **p = (struct rhash_head __rcu **)bkt;
@@ -587,7 +593,7 @@ static inline struct rhash_head *__rhashtable_lookup( 
		.ht = ht,

		.key = key,

	};

	struct rhash_lock_head __rcu * const *bkt;

	struct rhash_lock_head *const *bkt;

	struct bucket_table *tbl;

	struct rhash_head *he;

	unsigned int hash;
@@ -703,7 +709,7 @@ static inline void *__rhashtable_insert_fast( 
		.ht = ht,

		.key = key,

	};

	struct rhash_lock_head __rcu **bkt;

	struct rhash_lock_head **bkt;

	struct rhash_head __rcu **pprev;

	struct bucket_table *tbl;

	struct rhash_head *head;
@@ -989,7 +995,7 @@ static inline int __rhashtable_remove_fast_one( 
	struct rhash_head *obj, const struct rhashtable_params params,

	bool rhlist)

{

	struct rhash_lock_head __rcu **bkt;

	struct rhash_lock_head **bkt;

	struct rhash_head __rcu **pprev;

	struct rhash_head *he;

	unsigned int hash;
@@ -1141,7 +1147,7 @@ static inline int __rhashtable_replace_fast( 
	struct rhash_head *obj_old, struct rhash_head *obj_new,

	const struct rhashtable_params params)

{

	struct rhash_lock_head __rcu **bkt;

	struct rhash_lock_head **bkt;

	struct rhash_head __rcu **pprev;

	struct rhash_head *he;

	unsigned int hash;

lib/rhashtable.c

+14 −14
Original line number Diff line number Diff line
@@ -34,7 +34,7 @@ 


union nested_table {

	union nested_table __rcu *table;

	struct rhash_lock_head __rcu *bucket;

	struct rhash_lock_head *bucket;

};



static u32 head_hashfn(struct rhashtable *ht,
@@ -216,7 +216,7 @@ static struct bucket_table *rhashtable_last_table(struct rhashtable *ht, 
}



static int rhashtable_rehash_one(struct rhashtable *ht,

				 struct rhash_lock_head __rcu **bkt,

				 struct rhash_lock_head **bkt,

				 unsigned int old_hash)

{

	struct bucket_table *old_tbl = rht_dereference(ht->tbl, ht);
@@ -269,7 +269,7 @@ static int rhashtable_rehash_chain(struct rhashtable *ht, 
				    unsigned int old_hash)

{

	struct bucket_table *old_tbl = rht_dereference(ht->tbl, ht);

	struct rhash_lock_head __rcu **bkt = rht_bucket_var(old_tbl, old_hash);

	struct rhash_lock_head **bkt = rht_bucket_var(old_tbl, old_hash);

	int err;



	if (!bkt)
@@ -478,7 +478,7 @@ static int rhashtable_insert_rehash(struct rhashtable *ht, 
}



static void *rhashtable_lookup_one(struct rhashtable *ht,

				   struct rhash_lock_head __rcu **bkt,

				   struct rhash_lock_head **bkt,

				   struct bucket_table *tbl, unsigned int hash,

				   const void *key, struct rhash_head *obj)

{
@@ -529,7 +529,7 @@ static void *rhashtable_lookup_one(struct rhashtable *ht, 
}



static struct bucket_table *rhashtable_insert_one(struct rhashtable *ht,

						  struct rhash_lock_head __rcu **bkt,

						  struct rhash_lock_head **bkt,

						  struct bucket_table *tbl,

						  unsigned int hash,

						  struct rhash_head *obj,
@@ -584,7 +584,7 @@ static void *rhashtable_try_insert(struct rhashtable *ht, const void *key, 
{

	struct bucket_table *new_tbl;

	struct bucket_table *tbl;

	struct rhash_lock_head __rcu **bkt;

	struct rhash_lock_head **bkt;

	unsigned int hash;

	void *data;
@@ -1166,7 +1166,7 @@ void rhashtable_destroy(struct rhashtable *ht) 
}

EXPORT_SYMBOL_GPL(rhashtable_destroy);



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

struct rhash_lock_head **__rht_bucket_nested(const struct bucket_table *tbl,

					     unsigned int hash)

{

	const unsigned int shift = PAGE_SHIFT - ilog2(sizeof(void *));
@@ -1195,10 +1195,10 @@ struct rhash_lock_head __rcu **__rht_bucket_nested(const struct bucket_table *tb 
}

EXPORT_SYMBOL_GPL(__rht_bucket_nested);



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

struct rhash_lock_head **rht_bucket_nested(const struct bucket_table *tbl,

					   unsigned int hash)

{

	static struct rhash_lock_head __rcu *rhnull;

	static struct rhash_lock_head *rhnull;



	if (!rhnull)

		INIT_RHT_NULLS_HEAD(rhnull);
@@ -1206,7 +1206,7 @@ struct rhash_lock_head __rcu **rht_bucket_nested(const struct bucket_table *tbl, 
}

EXPORT_SYMBOL_GPL(rht_bucket_nested);



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

struct rhash_lock_head **rht_bucket_nested_insert(struct rhashtable *ht,

						  struct bucket_table *tbl,

						  unsigned int hash)

{