Merge branch 'rhashtables-cleanups'

NeilBrown says:

====================
Assorted rhashtables cleanups.

Following 7 patches are selections from a recent RFC series I posted
that have all received suitable Acks.

The most visible changes are that rhashtable-types.h is now preferred
for inclusion in include/linux/*.h rather than rhashtable.h, and
that the full hash is used - no bits a reserved for a NULLS pointer.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

10 files changed, 152 insertions, 165 deletions

diff --git a/include/linux/ipc.h b/include/linux/ipc.h
index 6cc2df7f7ac9..e1c9eea6015b 100644
--- a/include/linux/ipc.h
+++ b/include/linux/ipc.h
@@ -4,7 +4,7 @@
 
 #include <linux/spinlock.h>
 #include <linux/uidgid.h>
-#include <linux/rhashtable.h>
+#include <linux/rhashtable-types.h>
 #include <uapi/linux/ipc.h>
 #include <linux/refcount.h>
 
diff --git a/include/linux/ipc_namespace.h b/include/linux/ipc_namespace.h
index b5630c8eb2f3..6cea726612b7 100644
--- a/include/linux/ipc_namespace.h
+++ b/include/linux/ipc_namespace.h
@@ -9,7 +9,7 @@
 #include <linux/nsproxy.h>
 #include <linux/ns_common.h>
 #include <linux/refcount.h>
-#include <linux/rhashtable.h>
+#include <linux/rhashtable-types.h>
 
 struct user_namespace;
 
diff --git a/include/linux/mroute_base.h b/include/linux/mroute_base.h
index d633f737b3c6..fd436cdd4725 100644
--- a/include/linux/mroute_base.h
+++ b/include/linux/mroute_base.h
@@ -2,7 +2,7 @@
 #define __LINUX_MROUTE_BASE_H
 
 #include <linux/netdevice.h>
-#include <linux/rhashtable.h>
+#include <linux/rhashtable-types.h>
 #include <linux/spinlock.h>
 #include <net/net_namespace.h>
 #include <net/sock.h>
diff --git a/include/linux/rhashtable-types.h b/include/linux/rhashtable-types.h
new file mode 100644
index 000000000000..763d613ce2c2
--- /dev/null
+++ b/include/linux/rhashtable-types.h
@@ -0,0 +1,137 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Resizable, Scalable, Concurrent Hash Table
+ *
+ * Simple structures that might be needed in include
+ * files.
+ */
+
+#ifndef _LINUX_RHASHTABLE_TYPES_H
+#define _LINUX_RHASHTABLE_TYPES_H
+
+#include <linux/atomic.h>
+#include <linux/compiler.h>
+#include <linux/mutex.h>
+#include <linux/workqueue.h>
+
+struct rhash_head {
+	struct rhash_head __rcu		*next;
+};
+
+struct rhlist_head {
+	struct rhash_head		rhead;
+	struct rhlist_head __rcu	*next;
+};
+
+struct bucket_table;
+
+/**
+ * struct rhashtable_compare_arg - Key for the function rhashtable_compare
+ * @ht: Hash table
+ * @key: Key to compare against
+ */
+struct rhashtable_compare_arg {
+	struct rhashtable *ht;
+	const void *key;
+};
+
+typedef u32 (*rht_hashfn_t)(const void *data, u32 len, u32 seed);
+typedef u32 (*rht_obj_hashfn_t)(const void *data, u32 len, u32 seed);
+typedef int (*rht_obj_cmpfn_t)(struct rhashtable_compare_arg *arg,
+			       const void *obj);
+
+/**
+ * struct rhashtable_params - Hash table construction parameters
+ * @nelem_hint: Hint on number of elements, should be 75% of desired size
+ * @key_len: Length of key
+ * @key_offset: Offset of key in struct to be hashed
+ * @head_offset: Offset of rhash_head in struct to be hashed
+ * @max_size: Maximum size while expanding
+ * @min_size: Minimum size while shrinking
+ * @locks_mul: Number of bucket locks to allocate per cpu (default: 32)
+ * @automatic_shrinking: Enable automatic shrinking of tables
+ * @hashfn: Hash function (default: jhash2 if !(key_len % 4), or jhash)
+ * @obj_hashfn: Function to hash object
+ * @obj_cmpfn: Function to compare key with object
+ */
+struct rhashtable_params {
+	u16			nelem_hint;
+	u16			key_len;
+	u16			key_offset;
+	u16			head_offset;
+	unsigned int		max_size;
+	u16			min_size;
+	bool			automatic_shrinking;
+	u8			locks_mul;
+	rht_hashfn_t		hashfn;
+	rht_obj_hashfn_t	obj_hashfn;
+	rht_obj_cmpfn_t		obj_cmpfn;
+};
+
+/**
+ * struct rhashtable - Hash table handle
+ * @tbl: Bucket table
+ * @key_len: Key length for hashfn
+ * @max_elems: Maximum number of elements in table
+ * @p: Configuration parameters
+ * @rhlist: True if this is an rhltable
+ * @run_work: Deferred worker to expand/shrink asynchronously
+ * @mutex: Mutex to protect current/future table swapping
+ * @lock: Spin lock to protect walker list
+ * @nelems: Number of elements in table
+ */
+struct rhashtable {
+	struct bucket_table __rcu	*tbl;
+	unsigned int			key_len;
+	unsigned int			max_elems;
+	struct rhashtable_params	p;
+	bool				rhlist;
+	struct work_struct		run_work;
+	struct mutex                    mutex;
+	spinlock_t			lock;
+	atomic_t			nelems;
+};
+
+/**
+ * struct rhltable - Hash table with duplicate objects in a list
+ * @ht: Underlying rhtable
+ */
+struct rhltable {
+	struct rhashtable ht;
+};
+
+/**
+ * struct rhashtable_walker - Hash table walker
+ * @list: List entry on list of walkers
+ * @tbl: The table that we were walking over
+ */
+struct rhashtable_walker {
+	struct list_head list;
+	struct bucket_table *tbl;
+};
+
+/**
+ * struct rhashtable_iter - Hash table iterator
+ * @ht: Table to iterate through
+ * @p: Current pointer
+ * @list: Current hash list pointer
+ * @walker: Associated rhashtable walker
+ * @slot: Current slot
+ * @skip: Number of entries to skip in slot
+ */
+struct rhashtable_iter {
+	struct rhashtable *ht;
+	struct rhash_head *p;
+	struct rhlist_head *list;
+	struct rhashtable_walker walker;
+	unsigned int slot;
+	unsigned int skip;
+	bool end_of_table;
+};
+
+int rhashtable_init(struct rhashtable *ht,
+		    const struct rhashtable_params *params);
+int rhltable_init(struct rhltable *hlt,
+		  const struct rhashtable_params *params);
+
+#endif /* _LINUX_RHASHTABLE_TYPES_H */
diff --git a/include/linux/rhashtable.h b/include/linux/rhashtable.h
index 4e1f535c2034..eb7111039247 100644
--- a/include/linux/rhashtable.h
+++ b/include/linux/rhashtable.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * Resizable, Scalable, Concurrent Hash Table
  *
@@ -17,37 +18,18 @@
 #ifndef _LINUX_RHASHTABLE_H
 #define _LINUX_RHASHTABLE_H
 
-#include <linux/atomic.h>
-#include <linux/compiler.h>
 #include <linux/err.h>
 #include <linux/errno.h>
 #include <linux/jhash.h>
 #include <linux/list_nulls.h>
 #include <linux/workqueue.h>
-#include <linux/mutex.h>
 #include <linux/rculist.h>
 
+#include <linux/rhashtable-types.h>
 /*
  * The end of the chain is marked with a special nulls marks which has
- * the following format:
- *
- * +-------+-----------------------------------------------------+-+
- * | Base  |                      Hash                           |1|
- * +-------+-----------------------------------------------------+-+
- *
- * Base (4 bits) : Reserved to distinguish between multiple tables.
- *                 Specified via &struct rhashtable_params.nulls_base.
- * Hash (27 bits): Full hash (unmasked) of first element added to bucket
- * 1 (1 bit)     : Nulls marker (always set)
- *
- * The remaining bits of the next pointer remain unused for now.
+ * the least significant bit set.
  */
-#define RHT_BASE_BITS		4
-#define RHT_HASH_BITS		27
-#define RHT_BASE_SHIFT		RHT_HASH_BITS
-
-/* Base bits plus 1 bit for nulls marker */
-#define RHT_HASH_RESERVED_SPACE	(RHT_BASE_BITS + 1)
 
 /* Maximum chain length before rehash
  *
@@ -64,15 +46,6 @@
  */
 #define RHT_ELASTICITY	16u
 
-struct rhash_head {
-	struct rhash_head __rcu		*next;
-};
-
-struct rhlist_head {
-	struct rhash_head		rhead;
-	struct rhlist_head __rcu	*next;
-};
-
 /**
  * struct bucket_table - Table of hash buckets
  * @size: Number of hash buckets
@@ -102,132 +75,14 @@ struct bucket_table {
 	struct rhash_head __rcu *buckets[] ____cacheline_aligned_in_smp;
 };
 
-/**
- * struct rhashtable_compare_arg - Key for the function rhashtable_compare
- * @ht: Hash table
- * @key: Key to compare against
- */
-struct rhashtable_compare_arg {
-	struct rhashtable *ht;
-	const void *key;
-};
-
-typedef u32 (*rht_hashfn_t)(const void *data, u32 len, u32 seed);
-typedef u32 (*rht_obj_hashfn_t)(const void *data, u32 len, u32 seed);
-typedef int (*rht_obj_cmpfn_t)(struct rhashtable_compare_arg *arg,
-			       const void *obj);
-
-struct rhashtable;
-
-/**
- * struct rhashtable_params - Hash table construction parameters
- * @nelem_hint: Hint on number of elements, should be 75% of desired size
- * @key_len: Length of key
- * @key_offset: Offset of key in struct to be hashed
- * @head_offset: Offset of rhash_head in struct to be hashed
- * @max_size: Maximum size while expanding
- * @min_size: Minimum size while shrinking
- * @locks_mul: Number of bucket locks to allocate per cpu (default: 32)
- * @automatic_shrinking: Enable automatic shrinking of tables
- * @nulls_base: Base value to generate nulls marker
- * @hashfn: Hash function (default: jhash2 if !(key_len % 4), or jhash)
- * @obj_hashfn: Function to hash object
- * @obj_cmpfn: Function to compare key with object
- */
-struct rhashtable_params {
-	u16			nelem_hint;
-	u16			key_len;
-	u16			key_offset;
-	u16			head_offset;
-	unsigned int		max_size;
-	u16			min_size;
-	bool			automatic_shrinking;
-	u8			locks_mul;
-	u32			nulls_base;
-	rht_hashfn_t		hashfn;
-	rht_obj_hashfn_t	obj_hashfn;
-	rht_obj_cmpfn_t		obj_cmpfn;
-};
-
-/**
- * struct rhashtable - Hash table handle
- * @tbl: Bucket table
- * @key_len: Key length for hashfn
- * @max_elems: Maximum number of elements in table
- * @p: Configuration parameters
- * @rhlist: True if this is an rhltable
- * @run_work: Deferred worker to expand/shrink asynchronously
- * @mutex: Mutex to protect current/future table swapping
- * @lock: Spin lock to protect walker list
- * @nelems: Number of elements in table
- */
-struct rhashtable {
-	struct bucket_table __rcu	*tbl;
-	unsigned int			key_len;
-	unsigned int			max_elems;
-	struct rhashtable_params	p;
-	bool				rhlist;
-	struct work_struct		run_work;
-	struct mutex                    mutex;
-	spinlock_t			lock;
-	atomic_t			nelems;
-};
-
-/**
- * struct rhltable - Hash table with duplicate objects in a list
- * @ht: Underlying rhtable
- */
-struct rhltable {
-	struct rhashtable ht;
-};
-
-/**
- * struct rhashtable_walker - Hash table walker
- * @list: List entry on list of walkers
- * @tbl: The table that we were walking over
- */
-struct rhashtable_walker {
-	struct list_head list;
-	struct bucket_table *tbl;
-};
-
-/**
- * struct rhashtable_iter - Hash table iterator
- * @ht: Table to iterate through
- * @p: Current pointer
- * @list: Current hash list pointer
- * @walker: Associated rhashtable walker
- * @slot: Current slot
- * @skip: Number of entries to skip in slot
- */
-struct rhashtable_iter {
-	struct rhashtable *ht;
-	struct rhash_head *p;
-	struct rhlist_head *list;
-	struct rhashtable_walker walker;
-	unsigned int slot;
-	unsigned int skip;
-	bool end_of_table;
-};
-
-static inline unsigned long rht_marker(const struct rhashtable *ht, u32 hash)
-{
-	return NULLS_MARKER(ht->p.nulls_base + hash);
-}
-
-#define INIT_RHT_NULLS_HEAD(ptr, ht, hash) \
-	((ptr) = (typeof(ptr)) rht_marker(ht, hash))
+#define INIT_RHT_NULLS_HEAD(ptr)	\
+	((ptr) = (typeof(ptr)) NULLS_MARKER(0))
 
 static inline bool rht_is_a_nulls(const struct rhash_head *ptr)
 {
 	return ((unsigned long) ptr & 1);
 }
 
-static inline unsigned long rht_get_nulls_value(const struct rhash_head *ptr)
-{
-	return ((unsigned long) ptr) >> 1;
-}
-
 static inline void *rht_obj(const struct rhashtable *ht,
 			    const struct rhash_head *he)
 {
@@ -237,7 +92,7 @@ static inline void *rht_obj(const struct rhashtable *ht,
 static inline unsigned int rht_bucket_index(const struct bucket_table *tbl,
 					    unsigned int hash)
 {
-	return (hash >> RHT_HASH_RESERVED_SPACE) & (tbl->size - 1);
+	return hash & (tbl->size - 1);
 }
 
 static inline unsigned int rht_key_get_hash(struct rhashtable *ht,
@@ -376,11 +231,6 @@ static inline int lockdep_rht_bucket_is_held(const struct bucket_table *tbl,
 }
 #endif /* CONFIG_PROVE_LOCKING */
 
-int rhashtable_init(struct rhashtable *ht,
-		    const struct rhashtable_params *params);
-int rhltable_init(struct rhltable *hlt,
-		  const struct rhashtable_params *params);
-
 void *rhashtable_insert_slow(struct rhashtable *ht, const void *key,
 			     struct rhash_head *obj);
 
@@ -745,7 +595,7 @@ static inline void *__rhashtable_insert_fast(
 	lock = rht_bucket_lock(tbl, hash);
 	spin_lock_bh(lock);
 
-	if (unlikely(rht_dereference_bucket(tbl->future_tbl, tbl, hash))) {
+	if (unlikely(rcu_access_pointer(tbl->future_tbl))) {
 slow_path:
 		spin_unlock_bh(lock);
 		rcu_read_unlock();
diff --git a/include/net/inet_frag.h b/include/net/inet_frag.h
index ed07e3786d98..f4272a29dc44 100644
--- a/include/net/inet_frag.h
+++ b/include/net/inet_frag.h
@@ -2,7 +2,7 @@
 #ifndef __NET_FRAG_H__
 #define __NET_FRAG_H__
 
-#include <linux/rhashtable.h>
+#include <linux/rhashtable-types.h>
 
 struct netns_frags {
 	/* sysctls */
diff --git a/include/net/netfilter/nf_flow_table.h b/include/net/netfilter/nf_flow_table.h
index ba9fa4592f2b..0e355f4a3d76 100644
--- a/include/net/netfilter/nf_flow_table.h
+++ b/include/net/netfilter/nf_flow_table.h
@@ -4,7 +4,7 @@
 #include <linux/in.h>
 #include <linux/in6.h>
 #include <linux/netdevice.h>
-#include <linux/rhashtable.h>
+#include <linux/rhashtable-types.h>
 #include <linux/rcupdate.h>
 #include <linux/netfilter/nf_conntrack_tuple_common.h>
 #include <net/dst.h>
diff --git a/include/net/sctp/structs.h b/include/net/sctp/structs.h
index dbe1b911a24d..e0f962d27386 100644
--- a/include/net/sctp/structs.h
+++ b/include/net/sctp/structs.h
@@ -48,7 +48,7 @@
 #define __sctp_structs_h__
 
 #include <linux/ktime.h>
-#include <linux/rhashtable.h>
+#include <linux/rhashtable-types.h>
 #include <linux/socket.h>	/* linux/in.h needs this!!    */
 #include <linux/in.h>		/* We get struct sockaddr_in. */
 #include <linux/in6.h>		/* We get struct in6_addr     */
diff --git a/include/net/seg6.h b/include/net/seg6.h
index e029e301faa5..2567941a2f32 100644
--- a/include/net/seg6.h
+++ b/include/net/seg6.h
@@ -18,7 +18,7 @@
 #include <linux/ipv6.h>
 #include <net/lwtunnel.h>
 #include <linux/seg6.h>
-#include <linux/rhashtable.h>
+#include <linux/rhashtable-types.h>
 
 static inline void update_csum_diff4(struct sk_buff *skb, __be32 from,
 				     __be32 to)
diff --git a/include/net/seg6_hmac.h b/include/net/seg6_hmac.h
index 69c3a106056b..7fda469e2758 100644
--- a/include/net/seg6_hmac.h
+++ b/include/net/seg6_hmac.h
@@ -22,7 +22,7 @@
 #include <linux/route.h>
 #include <net/seg6.h>
 #include <linux/seg6_hmac.h>
-#include <linux/rhashtable.h>
+#include <linux/rhashtable-types.h>
 
 #define SEG6_HMAC_MAX_DIGESTSIZE	160
 #define SEG6_HMAC_RING_SIZE		256